NAU88C22YG

NAU88C22 24-bit Stereo Audio Codec with Speaker Driver Description The NAU88C22 is a low power, high quality CODEC for portable and general purpose audio applications. In addition to precision 24-bit stereo ADCs and DACs, this device integrates a broad range of additional functions to simplify implementation of complete audio system solutions. The NAU88C22 includes drivers for speaker, headphone, and differential or stereo line outputs, and integrates preamps for stereo differential microphones, significantly reducing external component requirements. Also, a fractional PLL is available to accurately generate any audio sample rate for the CODEC using any commonly available system clock from 8MHz through 33MHz. Advanced on-chip digital signal processing includes a 5-band equalizer, a 3-D audio enhancer, a mixed-signal automatic level control for the microphone or line input through the ADC, and a digital limiter/dynamic-rangecompressor (DRC) function for the playback path. Additional digital filtering options are available in the ADC path, to simplify implementation of specific application requirements such as “wind noise reduction” and speech band enhancement. The digital audio input/output interface can operate as either a master or a slave. The NAU88C22 operates with analog supply voltages from 2.5V to 3.6V, while the digital core can operate at 1.7V to conserve power. The loudspeaker BTL output pair and two auxiliary line outputs can operate using a 5V supply to increase output power capability, enabling the NAU88C22 to drive 1 Watt into an external speaker. Internal register controls enable flexible power saving modes by powering down sub-sections of the chip under software control. The NAU88C22 is specified for operation from -40°C to +85°C, and is available in a space-saving 32-lead QFN package. Key Features  DAC: 89dB SNR and -84dB THD (“A” weighted)  ADC: 89dB SNR and -78dB THD (“A” weighted)  Integrated BTL speaker driver: 1W into 8Ω  Integrated head-phone driver: 40mW into 16Ω  Integrated programmable microphone amplifier  Integrated line input and line output  On-chip PLL  Integrated DSP with specific functions:  5-band equalizer  3-D audio enhancement  Input automatic level control (ALC/AGC)/limiter  Output dynamic-range-compressor/limiter  Notch filter and high pass filter  Standard audio interfaces: PCM and I2S  Serial control interfaces with read/write capability  Real time readback of signal level and DSP status  Supports any sample rate from 8kHz, 48kHz, 96kHz and 192kHz Applications  Personal Media Players  Smartphones  Personal Navigation Devices  Portable Game Players  Camcorders  Digital Still Cameras  Portable TVs  Stereo Bluetooth Headsets NAU88C22 Datasheet Rev 0.6 Page 1 of 101 June, 2016 Headphones/ Line drivers LAUXIN AUXOUT2 RAUXIN ADC Filter LLIN LADC LMICN LMICP Stereo Microphone Interface Input Mixer DAC Filter Volume Control RLIN High Pass & Notch Filters RADC AUXOUT1 LDAC Volume Control LHP Limiter RDAC Output Mixer 5-band EQ RHP BTL Speaker 3D RMICN LSPKOUT RMICP RSPKOUT Digital Audio Interface Microphone Bias I2S Serial Control Interface PCM GPIO PLL LMICP 1 24 24 VSSSPK NAU88C22LYG MICBIAS VDDA LHP RHP VSSA VREF VDDSPK LSPKOUT 32 32 31 31 30 30 29 29 28 28 27 27 26 26 25 25 Pinout LMICN 2 23 23 RSPKOUT LLIN/GPIO2 3 22 22 AUXOUT2 RMICP 4 21 21 AUXOUT1 NAU88C22YG 32-lead QFN RoHS 15 16 CSB/GPIO1 SCLK SDIO 14 17 17 VDDB 8 13 BCLK 12 MODE VSSD 18 18 VDDC 7 11 FS MCLK LAUXIN 9 RAUXIN 19 19 10 20 20 6 DACIN 5 ADCOUT RMICN RLIN/GPIO3 Part Number Dimension Package Package Material NAU88C22YG 5 x 5 mm 32-QFN Green NAU88C22 Datasheet Rev 0.6 Page 2 of 101 June, 2016 Pin Descriptions Pin # Name Type 1 2 3 LMICP LMICN LLIN/GPIO2 4 5 6 RMICP RMICN RLIN/GPIO3 Analog Input Analog Input Analog Input / Digital I/O Analog Input Analog Input Analog Input / Digital I/O 7 8 9 10 11 12 13 14 15 FS BCLK ADCOUT DACIN MCLK VSSD VDDC VDDB CSB/GPIO1 Digital I/O Digital I/O Digital Output Digital Input Digital Input Supply Supply Supply Digital I/O 16 SCLK Digital Input 17 SDIO Digital I/O 18 19 20 21 22 23 24 MODE LAUXIN RAUXIN AUXOUT1 AUXOUT2 RSPKOUT VSSSPK Digital Input Analog Input Analog Input Analog Output Analog Output Analog Output Supply 25 26 LSPKOUT VDDSPK Analog Output Supply 27 28 29 30 31 32 VREF VSSA RHP LHP VDDA MICBIAS Reference Supply Analog Output Analog Output Supply Analog Output NAU88C22 Datasheet Rev 0.6 Functionality Left MICP Input (common mode) Left MICN Input Left Line Input / alternate Left MICP Input / GPIO2 Right MICP Input (common mode) Right MICN Input Right Line Input/ alternate Right MICP Input / Digital Output In 4-wire mode: Must be used for GPIO3 Digital Audio DAC and ADC Frame Sync Digital Audio Bit Clock Digital Audio ADC Data Output Digital Audio DAC Data Input Master Clock Input Digital Ground Digital Core Supply Digital Buffer (Input/Output) Supply 3-Wire MPU Chip Select or GPIO1 multifunction input/output 3-Wire MPU Clock Input / 2-Wire MPU Clock Input/Open Drain I/O needs external pull-up resistor 3-Wire MPU Data Input / 2-Wire MPU Data I/O /Open Drain I/O needs external pull-up resistor Control Interface Mode Selection Pin Left Auxiliary Input Right Auxiliary Input Headphone Ground / Mono Mixed Output / Line Output Headphone Ground / Line Output BTL Speaker Positive Output or Right high current output Speaker Ground (ground pin for RSPKOUT, LSPKOUT, AUXOUT2 and AUXTOUT1 output drivers) BTL Speaker Negative Output or Left high current output Speaker Supply (power supply pin for RSPKOUT, LSPKOUT, AUXOUT2 and AUXTOUT1 output drivers) Decoupling for Midrail Reference Voltage Analog Ground Headphone Positive Output / Line Output Right Headphone Negative Output / Line Output Left Analog Power Supply Microphone Bias Page 3 of 101 June, 2016 Figure 1: NAU88C22 Block Diagram NAU88C22 Datasheet Rev 0.6 Page 4 of 101 June, 2016 MICBIAS VREF RAUXIN RLIN RMICP RMICN LLIN LMICP LMICN LAUXIN 32 27 20 6 4 5 3 1 2 19 PLL MICROPHONE BIAS R R VDDA + - + Σ LADC MIX/BOOST 12 VSSD 7 9 BCLK FS ADCOUT 8 31 VDDA 28 VSSA DACIN 10 RADC Notch Filter ALC HPF RADC AUDIO INTERFACE (PCM/IIS) RADC MIX/BOOST Σ ALC Control 13 14 - VDDC VDDB 11 16 17 18 CSB/ MODE GPIO1 15 CONTROL INTERFACE (2-, 3- and 4-wire) RDAC Limiter LDAC MCLK SCLK SDIO RINMIX 24 VSSSPK 5 Band EQ 3D LINMIX 26 VDDSPK RMIX Σ RMAIN MIXER LMAIN MIXER Σ LMIX LDAC LINMIX RMIX LMIX RDAC LDAC RINMIX Σ Σ Σ RSPK SUBMIXER AUX2 MIXER AUX1 MIXER -6dB Normal -1.0X +1.5X -1.0X +1.5X -1.0X +1.5X -1.0X +1.5X 23 25 29 30 22 21 RSPKOUT LSPKOUT RHP LHP AUXOUT2 AUXOUT1 Electrical Characteristics Conditions: VDDC = 1.8V, VDDA = VDDB = VDDSPK = 3.3V (VDDSPK = 1.5*VDDA when Boost), MCLK = 12.288MHz, TA = +25°C, 1kHz signal, fs = 48kHz, 24-bit audio data, 64X oversampling rate, unless otherwise stated. Parameter Symbol Analog to Digital Converter (ADC) Full scale input signal 1 Comments/Conditions Min VINFS PGABST = 0dB PGAGAIN = 0dB Signal-to-noise ratio SNR Gain = 0dB, A-weighted Total harmonic distortion 2 THD+N Input = -3dB FS input Channel separation 1kHz input signal Digital to Analog Converter (DAC) driving RHP / LHP with 10kΩ / 50pF load Full-scale output Gain paths all at 0dB gain PSRR Units Vrms dBV dB dB dB VDDA / 3.3 Vrms 89 -84 100 dB dB dB +6 -15 3 dB dB dB VDDA / 3.3 Vrms (VDDA / 3.3) * 1.5 Vrms -64 dB -65 dB -59 dB -37 dB 96 dB VDDSPK=1.5 * VDDA 94 dB VDDSPK = 3.3V 80 dB VDDSPK = 1.5 * VDDA 76 dB +6 -57 1 85 dB dB dB dB Analog Outputs (RHP / LHP; RSPKOUT / LSPKOUT) Maximum programmable gain Minimum programmable gain Programmable gain step size Guaranteed monotonic Mute attenuation 1kHz full scale signal NAU88C22 Datasheet Rev 0.6 Max 1.0 0 89 -78 106 Signal-to-noise ratio SNR A-weighted Total harmonic distortion 2 THD+N RL = 10kΩ; full-scale signal Channel separation 1kHz input signal Output Mixers Maximum PGA gain into mixer Minimum PGA gain into mixer PGA gain step into mixer Guaranteed monotonic Speaker Output (RSPKOUT / LSPKOUT with 8Ω bridge-tied-load) 7 Full scale output 4 SPKBST = 1, VDDSPK=VDDA SPKBST = 0 VDDSPK= 1.5 * VDDA Total harmonic distortion 2 THD+N Po = 200mW, VDDSPK=3.3V Po = 320mW, VDDSPK = 3.3V Po = 860mW, VDDSPK = 1.5 * VDDA Po = 1000mW, VDDSPK = 1.5 * VDDA Signal-to-noise ratio SNR VDDSPK = 3.3V Power supply rejection ratio (50Hz - 22kHz) Typ Page 5 of 101 88 June, 2016 Electrical Characteristics, cont’d. Conditions: VDDC = 1.8V, VDDA = VDDB = VDDSPK = 3.3V (VDDSPK = 1.5*VDDA when Boost), MCLK = 12.288MHz, TA = +25°C, 1kHz signal, fs = 48kHz, 24-bit audio data, unless otherwise stated. Parameter Symbol Headphone Output (RHP / LHP with 32Ω load) 0dB full scale output voltage Signal-to-noise ratio SNR Total harmonic distortion 2 THD+N AUXOUT1 / AUXOUT2 with 10kΩ / 50pF load Full scale output Signal-to-noise ratio Total harmonic distortion 2 Channel separation Power supply rejection ratio (50Hz - 22kHz) Comments/Conditions Typ Max Units VDDA / 3.3 94 -86 Vrms dB dB -87 dB VDDA / 3.3 Vrms (VDDA / 3.3) * 1.5 Vrms 1kHz signal VDDSPK = 3.3V 91 -86 103 82 dB dB dB dB VDDSPK = 1.5 * VDDA 78 dB A-weighted RL = 16Ω, Po = 20mW, VDDA = 3.3V RL = 32Ω, Po = 20mW, VDDA = 3.3V AUX1BST = 0 AUX2BST = 0 VDDSPK=VDDA AUX1BST = 1 AUX2BST = 1 VDDSPK=1.5*VDDA SNR THD+N PSRR Min Microphone Inputs (LMICP, LMICN, RMICP, RMICN, LLIN, RLIN) and Programmable Gain Amplifier (PGA) Full scale input signal 1 PGABST = 0dB 1.0 Vrms PGAGAIN = 0dB 0 dBV Programmable gain -12 35.25 dB Programmable gain step size Guaranteed Monotonic 0.75 dB Mute Attenuation 120 dB Input resistance Inverting Input PGA Gain = 35.25dB 1.6 kΩ PGA Gain = 0dB 47 kΩ PGA Gain = -12dB 75 kΩ 94 kΩ Non-inverting Input Input capacitance 10 pF PGA output noise 0 to 20kHz, Gain set to 120 µV 35.25dB Input Boost Mixer Gain boost Boost disabled 0 dB Boost enabled 20 dB Gain range LLIN / RLIN or -12 6 dB LAUXIN / RAUXIN to boost/mixer Gain step size to boost/mixer 3 dB Auxiliary Analog Inputs (LAUXIN, RAUXIN) Full scale input signal 1 Gain = 0dB 1.0 Vrms 0 dBV Input resistance Aux direct-to-out path, only Input gain = +6.0dB 20 kΩ Input gain = 0.0dB 40 kΩ Input gain = -12dB 159 kΩ Input capacitance 10 pF NAU88C22 Datasheet Rev 0.6 Page 6 of 101 June, 2016 Electrical Characteristics, cont’d. Conditions: VDDC = 1.8V, VDDA = VDDB = VDDSPK = 3.3V (VDDSPK = 1.5*VDDA when Boost), MCLK = 12.288MHz, TA = +25°C, 1kHz signal, fs = 48kHz, 24-bit audio data, unless otherwise stated. Parameter Symbol Comments/Conditions Automatic Level Control (ALC) & Limiter: ADC path only Target record level Programmable gain Gain hold time 3 tHOLD Doubles every gain step, with 16 steps total Gain ramp-up (decay) 3 tDCY ALC Mode ALC = 0 Limiter Mode ALC = 1 Gain ramp-down (attack) 3 tATK ALC Mode ALC = 0 Limiter Mode ALC = 1 Mute Attenuation Microphone Bias Bias voltage VMICBIAS See Figure 3 Bias current source Output noise voltage Digital Input/Output Input HIGH level IMICBIAS Vn 1kHz to 20kHz VIL Min Typ Max Units -22.5 -1.5 -12 35.25 0 / 2.67 / 5.33 / … / 43691 dBFS dB ms 4 / 8 / 16 / … / 4096 ms 1 / 2 / 4 / … / 1024 ms 1 / 2 / 4 / … / 1024 ms 0.25 / 0.5 / 1 / … / 128 ms 120 dB 0.50, 0.60,0.65, 0.70, 0.75, 0.85, or 0.90 3 14 VDDA VDDA mA nV/√Hz 0.7 * VDDB Input LOW level VIH Output HIGH level VOH ILoad = 1mA Output LOW level VOL ILoad = -1mA V 0.3 * VDDB Input capacitance 0.9 * VDDB V 0.1 * VDDB 10 Notes 1. Full Scale is relative to the magnitude of VDDA and can be calculated as FS = VDDA/3.3. 2. Distortion is measured in the standard way as the combined quantity of distortion products plus noise. The signal level for distortion measurements is at 3dB below full scale, unless otherwise noted. 3. Time values scale proportionally with MCLK. Complete descriptions and definitions for these values are contained in the detailed descriptions of the ALC functionality. 4. With default register settings, VDDSPK should be 1.5xVDDA (but not exceeding maximum recommended operating voltage) to optimize available dynamic range in the AUXOUT1 and AUXOUT2 line output stages. Output DC bias level is optimized for VDDSPK = 5.0Vdc (boost mode) and VDDA = 3.3Vdc. 5. Unused analog input pins should be left as no-connection. 6. Unused digital input pins should be tied to ground. 7. 4 Ω loading is not recommended for speaker outputs NAU88C22 Datasheet Rev 0.6 Page 7 of 101 V June, 2016 V pF Absolute Maximum Ratings Condition Min Max Units VDDB, VDDC, VDDA supply voltages -0.3 +3.61 V VDDSPK supply voltage (default register configuration) -0.3 +5.80 V VDDSPK supply voltage (optional low voltage configuration) -0.3 +3.61 V Core Digital Input Voltage range VSSD – 0.3 VDDC + 0.30 V Buffer Digital Input Voltage range VSSD – 0.3 VDDB + 0.30 V Analog Input Voltage range VSSA – 0.3 VDDA + 0.30 V Industrial operating temperature -40 +85 °C Storage temperature range -65 +150 °C CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely influence product reliability and result in failures not covered by warranty. Operating Conditions Condition Symbol Min Digital supply range (Core) VDDC Digital supply range (Buffer) Analog supply range Typical Max Units 1.65 3.60 V VDDB 1.65 3.60 V VDDA 2.50 3.60 V Speaker supply (SPKBST=0) VDDSPK 2.50 5.50 V Speaker supply (SPKBST=1) VDDSPK 2.50 5.50 V Ground VSSD VSSA VSSSPK 0 V 1. VDDA must be ≥ VDDC. 2. VDDB must be ≥ VDDC. NAU88C22 Datasheet Rev 0.6 Page 8 of 101 June, 2016 Table of Contents 1 GENERAL DESCRIPTION .............................................................................................................................12 1.1.1 Analog Inputs ......................................................................................................................................12 1.1.2 Analog Outputs ...................................................................................................................................12 1.1.3 ADC, DAC, and Digital Signal Processing...........................................................................................13 1.1.4 Realtime Signal Level Readout and DSP Status .................................................................................13 1.1.5 Digital Interfaces .................................................................................................................................13 1.1.6 Clock Requirements ............................................................................................................................13 2 POWER SUPPLY .............................................................................................................................................14 2.1.1 Power-On Reset ..................................................................................................................................14 2.1.2 Power Related Software Considerations .............................................................................................14 2.1.3 Software Reset....................................................................................................................................14 3 INPUT PATH DETAILED DESCRIPTIONS ..................................................................................................16 3.1 Programmable Gain Amplifier (PGA) .........................................................................................................16 3.1.1 Zero Crossing Example .......................................................................................................................17 3.2 Positive Microphone Input (MICP) ..............................................................................................................17 3.3 Negative Microphone Input (MICN) ............................................................................................................18 3.4 Microphone biasing ....................................................................................................................................19 3.5 Line/Aux Input Impedance and Variable Gain Stage Topology ..................................................................19 3.6 Left and Right Line Inputs (LLIN and RLIN) ...............................................................................................22 3.7 Auxiliary inputs (LAUXIN, RAUXIN) ...........................................................................................................22 3.8 ADC Mix/Boost Stage .................................................................................................................................22 3.9 Input Limiter / Automatic Level Control (ALC) ............................................................................................23 3.9.1 Normal Mode Example Operation .......................................................................................................23 3.9.2 ALC Parameter Definitions ..................................................................................................................24 3.10 ALC Peak Limiter Function .........................................................................................................................25 3.10.1 ALC Normal Mode Example Using ALC Hold Time Feature ...............................................................25 3.11 Noise Gate (Normal Mode Only) ................................................................................................................25 3.12 ALC Example with ALC Min/Max Limits and Noise Gate Operation ...........................................................27 3.12.1 ALC Register Map Overview ...............................................................................................................27 3.13 4 Limiter Mode...............................................................................................................................................28 ADC DIGITAL BLOCK ..................................................................................................................................29 4.1 4.2 4.3 4.4 5 Sampling / Oversampling Rate, Polarity Control, Digital Passthrough .......................................................29 ADC Digital Volume Control and Update Bit Functionality .........................................................................30 ADC Programmable High Pass Filter .........................................................................................................30 Programmable Notch Filter.........................................................................................................................30 DAC DIGITAL BLOCK ..................................................................................................................................32 5.1 5.2 5.3 5.4 5.5 5.6 5.7 DAC Soft Mute ...........................................................................................................................................32 DAC AutoMute ...........................................................................................................................................32 DAC Sampling / Oversampling Rate, Polarity Control, Digital Passthrough ...............................................32 DAC Digital Volume Control and Update Bit Functionality .........................................................................33 DAC Automatic Output Peak Limiter / Volume Boost .................................................................................33 5-Band Equalizer ........................................................................................................................................34 3D Stereo Enhancement ............................................................................................................................35 NAU88C22 Datasheet Rev 0.6 Page 9 of 101 June, 2016 5.8 5.9 5.10 5.11 6 Companding ...............................................................................................................................................35 µ-law...........................................................................................................................................................35 A-law ..........................................................................................................................................................35 8-bit Word Length .......................................................................................................................................36 ANALOG OUTPUTS .......................................................................................................................................37 6.1 6.2 6.3 6.4 6.5 6.6 7 Main Mixers (LMAIN MIX and RMAIN MIX)................................................................................................37 Auxiliary Mixers (AUX1 MIXER and AUX2 MIXER) ....................................................................................37 Right Speaker Submixer ............................................................................................................................38 Headphone Outputs (LHP and RHP) .........................................................................................................38 Speaker Outputs ........................................................................................................................................39 Auxiliary Outputs ........................................................................................................................................41 MISCELLANEOUS FUNCTIONS ..................................................................................................................41 7.1 7.2 7.3 8 Slow Timer Clock .......................................................................................................................................41 General Purpose Inputs and Outputs (GPIO1, GPIO2, GPIO3) and Jack Detection ..................................42 Automated Features Linked to Jack Detection ...........................................................................................42 CLOCK SELECTION AND GENERATION ..................................................................................................43 8.1 Phase Locked Loop (PLL) General Description .........................................................................................44 8.1.1 Phase Locked Loop (PLL) Design Example ........................................................................................45 8.2 9 CSB/GPIO1 as PLL output .........................................................................................................................45 CONTROL INTERFACES ...............................................................................................................................47 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11 10 DIGITAL AUDIO INTERFACES ...................................................................................................................53 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 11 Selection of Control Mode ..........................................................................................................................47 2 2-Wire-Serial Control Mode (I C Style Interface) ........................................................................................47 2-Wire Protocol Convention........................................................................................................................47 2-Wire Write Operation ...............................................................................................................................48 2-Wire Read Operation ..............................................................................................................................49 SPI Control Interface Modes ......................................................................................................................49 SPI 3-Wire Write Operation ........................................................................................................................50 SPI 4-Wire 24-bit Write and 32-bit Read Operation...................................................................................50 SPI 4-Wire Write Operation ......................................................................................................................50 SPI 4-Wire Read Operation ........................................................................................................................51 Software Reset ...........................................................................................................................................52 Right-Justified Audio Data ..........................................................................................................................53 Left-Justified Audio Data ............................................................................................................................53 2 I S Audio Data ............................................................................................................................................54 PCM A Audio Data .....................................................................................................................................54 PCM B Audio Data .....................................................................................................................................55 PCM Time Slot Audio Data.........................................................................................................................55 Control Interface Timing .............................................................................................................................57 Audio Interface Timing: ..............................................................................................................................59 APPLICATION INFORMATION....................................................................................................................61 11.1 Typical Application Schematic ....................................................................................................................61 11.2 Recommended power up and power down sequences ..............................................................................62 11.2.1 Power Up (and after a software generated register reset) Procedure Guidance .................................62 11.2.2 Power Down ........................................................................................................................................62 11.2.3 Unused Input/Output Tie-Off Information ............................................................................................63 11.3 Power Consumption ...................................................................................................................................65 NAU88C22 Datasheet Rev 0.6 Page 10 of 101 June, 2016 11.4 12 13 APPENDIX A: DIGITAL FILTER CHARACTERISTICS ............................................................................67 APPENDIX B: COMPANDING TABLES .....................................................................................................73 13.1 13.2 14 15 16 17 Supply Currents of Specific Blocks .............................................................................................................66 µ-Law / A-Law Codes for Zero and Full Scale ............................................................................................73 µ-Law / A-Law Output Codes (Digital mW).................................................................................................73 APPENDIX C: DETAILS OF REGISTER OPERATION ..............................................................................74 APPENDIX D: REGISTER OVERVIEW .......................................................................................................94 PACKAGE DIMENSIONS ..............................................................................................................................96 ORDERING INFORMATION .........................................................................................................................99 NAU88C22 Datasheet Rev 0.6 Page 11 of 101 June, 2016 1 General Description The NAU88C22 is an upgrade to the WAU8822, and delivers reduced out-of-band noise energy, improved ALC and DSP signal processing, read-out capability of realtime signal level, readout of DSP status, and added controls for industry leading pop/click noise management. Additionally, handling of settings for 5-volt and 3volt operation are simplified, and all registers unique to Nuvoton are moved to higher addresses. This makes the part a direct hardware and software drop-in replacement for common industry parts. The NAU88C22 is a stereo part with identical left and right channels that share common support elements. Additionally, the right channel auxiliary output path includes a dedicated submixer that supports mixing the right auxiliary input directly into the right speaker output driver. This enables the right speaker channel to output audio that is not present on any other output. 1.1.1 Analog Inputs All inputs, except for the wide range programmable amplifier (PGA), have available analog input gain conditioning of -15dB through +6dB in 3dB steps. All inputs also have individual muting functions with excellent channel isolation and off-isolation from all outputs. All inputs are suitable for full quality, high bandwidth signals. Each of the left-right stereo channels includes a low noise differential PGA amplifier, programmable for highgain input. This may be used for a microphone level through line level source. Gain may be set from +35.25db through -12dB at the analog difference-amplifier type programmable amplifier input stage. A separate additional 20dB analog gain is available on this input path, between the PGA output and ADC mixer input. The output of the ADC mixer may be routed to the ADC and/or analog bypass to the analog output sections. Each channel also has a line level input. This input may be routed to the input PGA, and/or directly to the ADC input mixer. Each channel has a separate additional auxiliary input. This is a line level input which may be routed the ADC input mixer and/or directly to the analog output mixers. 1.1.2 Analog Outputs There are six high current analog audio outputs. These are very flexible outputs that can be used individually or in stereo pairs for a wide range of end uses. However, these outputs are optimized for specific functions and are described in this section using the functional names that are applicable to those optimized functions. Each output receives its signal source from built-in analog output mixers. These mixers enable a wide range of signal combinations, including muting of all sources. Additionally, each output has a programmable gain function, output mute function, and output disable function. The RHP and LHP headphone outputs are optimized for driving a stereo pair of headphones, and are powered from the main analog voltage supply rail, VDDA. These outputs may be coupled using traditional DC blocking series capacitors. Alternatively, these may be configured in a no-capacitor DC coupled design using a virtual ground at ½ VDDA provided by an AUXOUT analog output operating in the non-boost output mode. The AUXOUT1 and AUXOUT2 analog outputs are powered from the VDDSPK supply rail and VSSSPK ground return path. The supply rail may be the same as VDDA, or may be a separate voltage up to 5.5Vdc. This higher voltage enables these outputs to have an increased output voltage range and greater output power capability. The RSPKOUT and LSPKOUT loudspeaker outputs are powered from the VDDSPK power supply rail and VSSGND ground return path. RSPKOUT receives its audio signal via an additional submixer. This submixer supports combining a traditional alert sound (from the RAUXIN input) with the right channel headphone output mixer signal. This submixer also provides the signal invert function that is necessary for the normal BTL (Bridge Tied Load) configuration used to drive a high power external loudspeaker. Alternatively, each loudspeaker output may be used individually as a separate high current analog output driver. A programmable low-noise MICBIAS microphone bias supply output is included. This is suitable for both conventional electret (ECM) type microphone, and to power the newer MEMS all-silicon type microphones. NAU88C22 Datasheet Rev 0.6 Page 12 of 101 June, 2016 1.1.3 ADC, DAC, and Digital Signal Processing Each left and right channel has an independent high quality ADC and DAC associated with it. These are high performance, 24-bit delta-sigma converters that are suitable for a very wide range of applications. The ADC and DAC functions are each individually supported by powerful analog mixing and routing. The ADC output may be routed to the digital output path and/or to the input of the DAC in a digital passthrough mode. The ADC and DAC blocks are also supported by advanced digital signal processing subsystems that enable a very wide range of programmable signal conditioning and signal optimizing functions. All digital processing is with 24-bit precision, as to minimize processing artifacts and maximize the audio dynamic range supported by the LL. The ADCs are supported by a wide range, mixed-mode Automatic Level Control (ALC), a high pass filter, and a notch filter. All of these features are optional and highly programmable. The high pass filter function is intended for DC-blocking or low frequency noise reduction, such as to reduce unwanted ambient noise or “wind noise” on a microphone input. The notch filter may be programmed to greatly reduce a specific frequency band or frequency, such as a 50Hz, 60Hz, or 217Hz unwanted noise. The DACs are supported by a programmable limiter/DRC (Dynamic Range Compressor). This is useful to optimize the output level for various applications and for use with small loudspeakers. This is an optional feature that may be programmed to limit the maximum output level and/or boost an output level that is too small. Digital signal processing is also provided for a 3D Audio Enhancement function, and for a 5-Band Equalizer. These features are optional, and are programmable over wide ranges. This pair of digital processing features may be applied jointly to either the ADC audio path or to the DAC audio path, but not to both paths simultaneously. 1.1.4 Realtime Signal Level Readout and DSP Status In addition to general read-back ability of all its registers, the NAU88C22 includes powerful capabilities to readback signal related DSP information not possible with almost any other CODEC. In conjunction with the ALC, the software by means of the readback function can determine the realtime signal level at the inputs, as well as the realtime actual gain setting being used by the ALC. Additionally, other signal related information can also be determined, such as the Noise Gate on/off status and Automute/Softmute function status. These greatly enhance both the ability to optimize software and to enhance dynamic end product functionality. 1.1.5 Digital Interfaces Command and control of the device is accomplished using a 2-wire/3-wire/4-wire serial control interface. This is a simple, but highly flexible interface that is compatible with many commonly used command and control serial data protocols and host drivers. Digital audio input/output data streams are transferred to and from the device separately from command and control. The digital audio data interface supports either I2S or PCM audio data protocols, and is compatible with commonly used industry standard devices that follow either of these two serial data formats. 1.1.6 Clock Requirements The clocking signals required for the audio signal processing, audio data I/O, and control logic may be provided externally, or by optional operation of a built-in PLL (Phase Locked Loop). The PLL is provided as a low cost, zero external component count optional method to generate required clocks in almost any system. The PLL is a fractional-N divider type design, which enables generating accurate desired audio sample rates derived from a very wide range of commonly available system clocks. The frequency of the system clock provided as the PLL reference frequency may be any stable frequency in the range between 8MHz and 33MHz. Because the fractional-N multiplication factor is a very high precision 24-bit value, any desired sample rate supported by the NAU88C22 can be generated with very high accuracy, typically limited by the accuracy of the external reference frequency. Reference clocks and sample rates outside of these ranges are also possible, but may involve performance tradeoffs and increased design verification. NAU88C22 Datasheet Rev 0.6 Page 13 of 101 June, 2016 2 Power Supply This device has been designed to operate reliably using a wide range of power supply conditions and poweron/power-off sequences. There are no special requirements for the sequence or rate at which the various power supply pins change. Any supply can rise or fall at any time without harm to the device. However, pops and clicks may result from some sequences. Optimum handling of hardware and software power-on and power-off sequencing is described in more detail in the Applications section of this document. 2.1.1 Power-On Reset The NAU88C22 does not have an external reset pin. The device reset function is automatically generated internally when power supplies are too low for reliable operation. The internal reset is generated any time that either VDDA or VDDC is lower than is required for reliable maintenance of internal logic conditions. The reset threshold voltage for VDDA and VDDC is approximately 1.4Vdc. If both VDDA and VDDC are being reduced at the same time, the threshold voltage may be slightly lower. Note that these are much lower voltages than are required for normal operation of the chip. These values are mentioned here as general guidance as to overall system design. If either VDDA or VDDC is below its respective threshold voltage, an internal reset condition is asserted. During this time, all registers and controls are set to the hardware determined initial conditions. Software access during this time will be ignored, and any expected actions from software activity will be invalid. When both VDDA and VDDC reach a value above their respective thresholds, an internal reset pulse is generated which extends the reset condition for an additional time. The duration of this extended reset time is approximately 50 microseconds, but not longer than 100 microseconds. The reset condition remains asserted during this time. If either VDDA or VDDC at any time becomes lower than its respective threshold voltage, a new reset condition will result. The reset condition will continue until both VDDA and VDDC again higher than their respective thresholds. After VDDA and VDDC are again both greater than their respective threshold voltage, a new reset pulse will be generated, which again will extend the reset condition for not longer than an additional 100 microseconds. 2.1.2 Power Related Software Considerations There is no direct way for software to determine that the device is actively held in a reset condition. If there is a possibility that software could be accessing the device sooner than 100 microseconds after the VDDA and VDDC supplies are valid, the reset condition can be determined indirectly. This is accomplished by writing a value to any register other than register 0x00, with that value being different than the power-on reset initial values. The optimum choice of register for this purpose may be dependent on the system design, and it is recommended the system engineer choose the register and register test bit for this purpose. After writing the value, software will then read back the same register. When the register test bit reads back as the new value, instead of the power-on reset initial value, software can reliably determine that the reset condition has ended. Although it is not required, it is strongly recommended that a Software Reset command should be issued after power-on and after the power-on reset condition is ended. This will help insure reliable operation under every power sequencing condition that could occur. If there is any possibility that VDDA or VDDC could be unreliable during system operation, software may be designed to monitor whether a power-on reset condition has happened. This can be accomplished by writing a test bit to a register that is different from the power-on initial conditions. This test bit should be a bit that is never used for any other reason, and does not affect desired operation in any way. Then, software at any time can read this bit to determine if a power-on reset condition has occurred. If this bit ever reads back other than the test value, then software can reliably know that a power-on reset event has occurred. Software can subsequently re-initialize the device and the system as required by the system design. 2.1.3 Software Reset All chip registers can be reset to power-on default conditions by writing any value to register 0, using any of the control modes. Writing valid data to any other register disables the reset, but all registers need to have the NAU88C22 Datasheet Rev 0.6 Page 14 of 101 June, 2016 correct operating data written. See the applications section on powering NAU88C22 up for information on avoiding pops and clicks after a software reset. NAU88C22 Datasheet Rev 0.6 Page 15 of 101 June, 2016 3 Input Path Detailed Descriptions The NAU88C22 provides multiple inputs to acquire and process audio signals from microphones or other sources with high fidelity and flexibility. There are left and right input paths, each with three input pins, which can be used to capture signals from single-ended, differential or dual-differential microphones. These input channels each include a programmable gain amplifier (PGA). The outputs of the PGAs, plus two additional auxiliary inputs, are then connected to the input boost/mix stages for maximum flexibility handling various signal sources. All inputs are maintained at a DC bias at approximately ½ of the AVDD supply voltage. Connections to these inputs should be AC-coupled by means of DC blocking capacitors suitable for the device application. Differential microphone input (MICN & MICP pins) and Programmable Gain Amplifier The NAU88C22 features a low-noise, high common mode rejection ratio (CMRR), differential microphone input pair, MICP and MICN, which are connected to a PGA gain stage. The differential input structure is essential in noisy digital systems where amplification of low-amplitude analog signals is necessary such as in portable digital media devices and cell phones. Differential inputs very useful to reduce ground noise in systems in which there are ground voltage differences between different chips and other components. When properly implemented, the differential input architecture offers an improved power-supply rejection ratio (PSRR) and higher ground noise immunity. 3.1 Programmable Gain Amplifier (PGA) Each PGA supports three possible inputs, MICP, MICN, and LIN. These are the microphone differential pair and a separate line level input. The PGA has a gain range of -12dB through +35.25dB in evenly spaced decibel increments of 0.75dB. Operation of the PGA is subject to control by the following registers: R2 Power management controls for the left and right PGA R2 Power management controls for ADC Mix/Boost (must be “on” for any PGA path to function) R7 Zero crossing timeout control R32 Automatic Level Control (ALC) for the left and right PGA R44 Input selection options for the left and right PGA R45 Volume (gain), mute, update bit, and zero crossing control for the left PGA R46 Volume (gain), mute, update bit, and zero crossing control for the right PGA Important: The R45 and R46 update bits are write-only bits. The primary intended purpose of the update bit is to enable simultaneous changes to both the left and right PGA volume values, even though these values must be written sequentially. When there is a write operation to either R45 or R46 volume settings, but the update bit is not set (value = 0), the new volume setting is stored as pending for the future, but does not go into effect. When there is a write operation to either R45 or R46 and the update bit is set (value = 1), then the new value in the register being written is immediately put into effect, and any pending value in the other PGA volume register is put into effect at the same time. Note: If the ALC automatic level control is enabled, the function of the ALC is to automatically adjust the R45 or R46 volume setting. If ALC is enabled for the left or right, or both channels, then software should avoid changing the volume setting for the affected channel or channels. The reason for this is to avoid unexpected volume changes caused by competition between the ALC and the direct software control of the volume setting. Zero-Crossing controls are implemented to suppress clicking sounds that may occur when volume setting changes take place while an audio input signal is active. When the zero crossing function is enabled (logic = 1), any volume change for the affected channel will not take place until the audio input signal passes through the zero point in its peak-to-peak swing. This prevents any instantaneous voltage change to the audio signal caused by volume setting changes. If the zero crossing function is disabled (logic = 0), volume changes take place instantly on condition of the Update Bit, but without regard to the instantaneous voltage level of the affected audio input signal. The R7 zero crossing timeout control is an additional feature to limit the amount of time that a volume change to the PGA is delayed pending a zero crossing event. If the input signal is such that there are no zero crossing events, and the timeout control is enabled (level = 1), any new volume setting to either PGA will automatically NAU88C22 Datasheet Rev 0.6 Page 16 of 101 June, 2016 be put into effect after between 2.5 and 3.5 periods of the Slow Timer Clock (see description under “Miscellaneous Functions”). 3.1.1 Zero Crossing Example This drawing shows in a graphical form the problem and benefits of using the zero crossing feature. There is a major audible improvement as a result of using the zero crossing feature. PGA Output with Zero Cross Enabled PGA Output with Zero Cross Disabled PGA Input Gain Change Figure 2: Zero Crossing Gain Update Operation PGA Gain R45, R46 Input Selection R44 R MICN R MICP To ADC Mix/Boost R VREF -12 dB to +35.25 dB LIN R VREF Figure 3: PGA Input Structure Simplified Schematic 3.2 Positive Microphone Input (MICP) The positive (non-inverting) microphone input (MICP) can be used separately, or as part of a differential input configuration. This input pin connects to the positive (non-inverting) terminal of the PGA amplifier under control of register R44. When the R44 associated control bit is set (logic = 1), a switch connects MICP to the PGA input. When the associated control bit is not set (logic = 0), the MICP pin is connected to a resistor of approximately 30kΩ which is tied to VREF. The purpose of the tie to VREF is to reduce any pop or click sound by keeping the DC level of the MICP pin close to VREF at all times. Note: If the MICP signal is not used differentially with MICN, the PGA gain values will be valid only if the MICN pin is terminated to a low impedance signal point. This termination should normally be an AC coupled path to signal ground. NAU88C22 Datasheet Rev 0.6 Page 17 of 101 June, 2016 This input impedance is constant regardless of the gain value. The nominal input impedance for this input is given by the following table. Impedance for specific gain values not listed in this table can be estimated through interpolation between listed values. Nominal Input Impedance LMICP & RMICP to non-inverting PGA input or LLIN & RLIN to non-inverting PGA input Gain (dB) -12 -9 -6 -3 0 3 6 9 12 18 30 35.25 Impedance (kΩ) 94 94 94 94 94 94 94 94 94 94 94 94 Table 1: Microphone and Line Non-Inverting Input Impedances 3.3 Negative Microphone Input (MICN) The negative (inverting) microphone input (MICN) can be used separately, or as part of a differential input configuration. This input pin connects to the negative (inverting) terminal of the PGA amplifier under control of register R44. When the R44 associated control bit is set (logic = 1), a switch connects MICP to the PGA input. When the associated control bit is not set (logic = 0), the MICN pin is connected to a resistor of approximately 30kΩ which is tied to VREF. The purpose of the tie to VREF is to reduce any pop or click sound by keeping the DC level of the MICN pin close to VREF at all times. It is important for a system designer to know that the MICN input impedance varies as a function of the selected PGA gain. This is normal and expected for a difference amplifier type topology. The nominal resistive impedance values for this input over the possible gain range are given by the following table. Impedance for specific gain values not listed in this table can be estimated through interpolation between listed values. Nominal Input Impedance LMICN or RMICN to inverting PGA input Gain (dB) -12 -9 -6 -3 0 3 6 9 12 18 30 35.25 Impedance (kΩ) 75 69 63 55 47 39 31 25 19 11 2.9 1.6 Table 2: Microphone Inverting Input Impedances System designers should also note that at the highest gain values, the input impedance is relatively low. For most inputs, the best strategy if higher gain values are needed is to use the input PGA in combination with the +20dB gain boost available on the PGA Mix/Boost stage that immediately follows the PGA output. A good NAU88C22 Datasheet Rev 0.6 Page 18 of 101 June, 2016 guideline is to use the PGA gain for up to around 20dB of gain. If more gain than this is required and the lower input impedance of the PGA at high gains is a problem, a combination of the PGA and boost stage should be used. In this type of combined gain configuration, it is preferred to have at least 6dB gain at the PGA input stage to benefit from the PGA low noise characteristics. 3.4 Microphone biasing The MICBIAS pin provides a low-noise microphone DC bias voltage as may be required for operation of an external microphone. This built-in feature can typically provide up to 3mA of microphone bias current. This DC bias voltage is suitable for powering either traditional ECM (electret) type microphones, or for MEMS types microphones with an independent power supply pin. Seven different bias voltages are available for optimum system performance, depending on the specific application. The microphone bias pin normally requires an external filtering capacitor as shown on the schematic in the Application section. The microphone bias function is controlled by the following registers: R1 Power control for MICBIAS feature (enabled when bit 4 = 1) R58 Optional low-noise mode and different bias voltage levels (enabled when bit 4 = 1) R44 Primary MICBIAS voltage selection The low-noise feature results in greatly reduced noise in the external MICBIAS voltage by placing a resistor of approximately 200-ohms in series with the output pin. This creates a low pass filter in conjunction with the external micbias filter capacitor, but without any additional external components. The low noise feature is enabled when the mode control bit 4 in register R58 is set (level = 1) VREF Register 58, bit 4 MICBIASM Register 1, bit 4 MICBIASEN Register 44, Bits 7-8 00 Register 58, Bit 4 0 Microphone Bias Voltage 0.90 * VDDA 01 0 0.65 * VDDA 10 0 0.75 * VDDA 11 0 0.50 * VDDA 00 1 0.85 * VDDA 01 1 0.60 * VDDA 10 1 0.70 * VDDA 11 1 0.50 * VDDA MICBIAS R R Register 44, bits 7-8 MICBIASV Figure 4: Microphone Bias Generator 3.5 Line/Aux Input Impedance and Variable Gain Stage Topology Except for the input PGAs, other variable gain stages are implemented similarly to the simplified schematic shown here. The gain value changes affect input impedance in the ranges detailed in the description of each type of input path. If a path is in the “not selected” condition, then the input impedance will be in a high impedance condition. If an external input pin is not used anywhere in the system, it will be coupled to a DC tie-off of approximately 30kΩ coupled to VREF. The unused input/output tie-off function is explained in more detail in the Application Information section of this document. NAU88C22 Datasheet Rev 0.6 Page 19 of 101 June, 2016 Gain Value Adjustment “Not Selected” Switch R Input R To Next Stage VREF -15 dB to +6.0 dB Figure 5: Variable Gain Stage Simplified Schematic NAU88C22 Datasheet Rev 0.6 Page 20 of 101 June, 2016 The input impedance presented to these inputs depends on the input routing choices and gain values. If an input is routed to more than one internal input node, then the effective input impedance will be the parallel combination of the impedance of the multiple nodes that are used. The impedance looking into the PGA noninverting input is constant as listed in the section discussing the microphone input PGAs. The nominal resistive input impedances looking into the ADC Mix/Boost input inputs are listed in the following table: Inputs LAUXIN & RAUXIN to L/RADC MIX/BOOST amp or LLIN & RLIN to L/RADC MIX/BOOST amp Gain (dB) Not Selected -12 -9 -6 -3 0 3 6 Impedance (kΩ) High-Z 159 113 80 57 40 28 20 Table 3: MIX/BOOST Amp Impedances The nominal resistive input impedances presented to signal pins that are directly routed to an output mixer are listed in the following table. If an input is connected to other active nodes, then this value is in parallel with the resistive input impedance of any such other node. Inputs LAUXIN & RAUXIN to bypass amp Or RAUXIN to RSPK SUBMIXER amp Gain (dB) -15 -12 -9 -6 -3 0 3 6 Impedance (kΩ) 225 159 113 80 57 40 28 20 Table 4: Bypass Amp and RSPK SUBMIXER Input Impedances NAU88C22 Datasheet Rev 0.6 Page 21 of 101 June, 2016 3.6 Left and Right Line Inputs (LLIN and RLIN) A third possible input to the left or right PGA is an optional associated LIN left or right line level input. These inputs may be routed to the PGA non-inverting input, and/or connect directly to the ADC Mixer/Boost stage. If routed to the PGA, this signal is processed as an alternate pin for the MICP signal. LIN may be received differentially in relation to the MICN pin and has available the same gain range as for MICP. As in the operational case of using the MICP input, the MICN input must have a low impedance path to signal ground, so that the gain values chosen in the PGA are valid. Note: It not recommended that both the LIN line input path to the PGA and the MICP path to the PGA be enabled at the same time. This will cause the differential gain to be unbalanced, and result in poor common mode rejection. Also, this will result in the LIN and MICP signals being connected together through internal chip resistors. The line input pins, may alternatively be configured to operate as a GPIO (General Purpose Input/Output) logic input pin. This intended purpose is static logic voltage level sensing to determine if a headset is present or not as part of a physical detection of a possible external headset. Only one GPIO pin at any one time can be assigned for this purpose. Registers that affect operation of the LLIN and RLIN inputs are: R2 ADC Mix/Boost power control (must be “on” for any LIN path to function) R9 GPIO selection for headset detect function R44 PGA input selection control bits If selected, all other PGA control registers (see PGA description) R47 Left line input ADC Mix/Boost volume and mute (bits 4, 5, and 6) R48 Right line input ADC Mix/Boost volume and mute (bits 4, 5, and 6) 3.7 Auxiliary inputs (LAUXIN, RAUXIN) The left and right channels each have an additional input that is separate from the programmable amplifier stage. These are the left and right auxiliary inputs, LAUXIN and RAUXIN. These inputs may be routed to either or both the associated ADC Mix/Boost stage, or the associated LCH MIX or RCH MIX output mixer. The RAUXIN input may additionally be routed to the Right Speaker Submixer in the analog output section. This path enables a sound to be output from the RSPKOUT speaker output, but without being audible anywhere else in the system. One purpose of this path is to support a traditional “beep” sound, such as from a microprocessor toggle bit. This is a historical application scenario which is now uncommon. The auxiliary inputs are affected by the following registers: ADC Mix/Boost if used (see ADC Mix/Boost section) LCH MIXER or RCH MIXER if used (see output mixer section) BEEP MIXER if used (see Beep Mixer section) Note: no power control registers affect only the auxiliary inputs The input impedance presented to these inputs depends on the input routing choices and gain values. If an input is routed to more than one internal input node, then the effective input impedance will be the parallel combination of the impedance of the multiple nodes that are used. The input impedances presented to these inputs are the same as those listed for the LLIN and RLIN inputs. 3.8 ADC Mix/Boost Stage The left and right channels each have an independent ADC Mix/Boost stage. Most analog input signals must pass through the ADC Mix/Boost stage before use anywhere else in this device. The only analog inputs that can completely bypass the ADC Mix/Boost stage are the LAUXIN and RAUXIN auxiliary inputs. The ADC mixer stage has three inputs, AUX, LIN, and PGA. The AUX input is for the associated auxiliary input, and the LIN is for the associated line input. The PGA input is an internal connection to the associated programmable gain amplifier servicing the microphone and line inputs. NAU88C22 Datasheet Rev 0.6 Page 22 of 101 June, 2016 All three inputs to the ADC Mix/Boost stage can be independently muted, and all three inputs have independent gain controls. The AUX and LIN inputs have an available gain range of -12dB through +6dB in 3dB steps. The PGA input path has a choice of 0dB or 20dB of gain in addition to the gain in the PGA. Registers that affect the ADC Mix/Boot stage are: R2 Power control for left and right channels R45 mute function for left channel PGA (bit 6 = 0 = muted condition) R46 mute function for right channel PGA (bit 6 = 0 = muted condition) R47 gain and mute control for left channel AUX and LIN R48 gain and mute control for right channel AUX and LIN 3.9 Input Limiter / Automatic Level Control (ALC) The input section of the NAU88C22 is supported by additional combined digital and analog functionality which implement an Automatic Level Control (ALC) function. This can be very useful to automatically manage the analog input gain to optimize the signal level at the output of the programmable amplifier. The ALC can automatically amplify input signals that are too small, or decrease the amplitude if the signals are too loud. This system also helps to prevent clipping (overdrive) at the input of the ADC while maximizing the full dynamic range of the ADC. The ALC may be operated in the normal mode just described, on in a special limiter mode of operation. The limiter mode is a faster mode of operation, the primary purpose of which is to limit too-loud signals. The limiter mode of operation is described after this section which provides details on the normal mode of operation. The functional block architecture for the ALC is shown below. The ALC monitors the output of the ADC, measured after the digital decimator. The ADC output is fed into a peak detector, which updates the measured peak value whenever the absolute value of the input signal is higher than the current measured peak. The measured peak gradually decays to zero unless a new peak is detected, allowing for an accurate measurement of the signal envelope. The peak value is used by a logic algorithm to determine whether the PGA input gain should be increased, decreased, or remain the same. Rate Convert/ Decimator PGA ADC Filter Digital Decimator ALC Figure 6: ALC Block Diagram 3.9.1 Normal Mode Example Operation Immediately following is a simple example of the ALC operation. In the steady state at the beginning of the example time sequence, the PGA gain is at a steady value which results in the desired output level from the ADC. When the input signal suddenly becomes louder, the ALC reduces volume at a register determined rate and step size. This continues until the output level of the ADC is again at the desired target level. When the input signal suddenly becomes quiet, the ALC increases volume at a register determined rate and step size. When the output level from the ADC again reaches the target level, and now the input remains at a constant level, the ALC remains in a steady state. NAU88C22 Datasheet Rev 0.6 Page 23 of 101 June, 2016 PGA Input PGA Output PGA Gain Figure 7: ALC Normal Mode Operation 3.9.2 ALC Parameter Definitions Automatic level and volume control features are complex and have difficult to understand traditional names for many features and controls. This section defines some terms so that the explanations of this subsystem are more clear. ALC Maximum Gain: Register 32 (ALCMXGAIN) This sets the maximum allowed gain in the PGA during normal mode ALC operation. In the Limiter mode of ALC operation, the ALCMXGAIN value is not used. In the Limiter mode, the maximum gain allowed for the PGA is set equal to the pre-existing PGA gain value that was in effect at the moment in time that the Limiter mode is enabled. ALC Minimum Gain: Register 32 (ALCMNGAIN) This sets the minimum allowed gain in the PGA during all modes of ALC operation. This is useful to keep the AGC operating range close to the desired range for a given application scenario. ALC Target Value: Register 33 (ALCSL) Determines the value used by the ALC logic decisions comparing this fixed value with the output of the ADC. This value is expressed as a fraction of Full Scale (FS) output from the ADC. Depending on the logic conditions, the output value used in the comparison may be either the instantaneous value of the ADC, or otherwise a time weighted average of the ADC peak output level. ALC Attack Time: Register 34 (ALCATK) Attack time refers to how quickly a system responds to an increasing volume level that is greater than some defined threshold. Typically, attack time is much faster than decay time. In the NAU88C22, when the absolute value of the ADC output exceeds the ALC Target Value, the PGA gain will be reduced at a step size and rate determined by this parameter. When the peak ADC output is at least 1.5dB lower than the ALC Target Value, the stepped gain reduction will halt. ALC Decay Time: Register 34 (ALCDCY) Decay time refers to how quickly a system responds to a decreasing volume level. Typically, decay time is much slower than attack time. When the ADC output level is below the ALC Target value by at least 1.5dB, the PGA gain will increase at a rate determined by this parameter. The decay time constant is determined by the setting in register 34, bits 4 to 7 (ALCDCY), which sets the delay between increases in gain. In Limiter mode, the time constants are faster than in ALC mode. (See Detailed Register Map.) ALC Hold Time Register 33 (ALCHLD) Hold time refers to a duration of time when no action is taken. This is typically to avoid undesirable sounds that can happen when an ALC responds too quickly to a changing input signal. The use and amount of hold time is very application specific. In the NAU88C22, the hold time value is the duration of time that the ADC output peak value must be less than the target value before there is an actual gain increase. NAU88C22 Datasheet Rev 0.6 Page 24 of 101 June, 2016 3.10 ALC Peak Limiter Function To reduce clipping and other bad audio effects, all ALC modes include a peak limiter function. This implements an emergency PGA gain reduction when the ADC output level exceeds a built-in maximum value. When the ADC output exceeds 87.5% of full scale, the ALC block ramps down the PGA gain at the maximum ALC Attack Time rate, regardless of the mode and attack rate settings, until the ADC output level has been reduced below the emergency limit threshold. This limits ADC clipping if there is a sudden increase in the input signal level. 3.10.1 ALC Normal Mode Example Using ALC Hold Time Feature Input signals with different characteristics (e.g., voice vs. music) may require different settings for this parameter for optimum performance. Increasing the ALC hold time prevents the ALC from reacting too quickly to brief periods of silence such as those that may appear in music recordings; having a shorter hold time, may be useful in voice applications where a faster reaction time helps to adjust the volume setting for speakers with different volumes. The waveform below shows the operation of the ALCHLD parameter. 16ms delay for ALCHT = 0100 PGA Input PGA Output PGA Gain Hold Delay Change Figure 8: ALC Hold Delay Change 3.11 Noise Gate (Normal Mode Only) A noise gate threshold prevents ALC amplification of noise when there is no input signal, or no signal above an expected background noise level. The noise gate is enabled by setting register 35, bit 3 (NGEN), HIGH, and the threshold level is set in register 35, bits 0 to 2 (NGTH). This does not remove noise from the signal; when there is no signal or a very quiet signal (pause) composed mostly of noise, the ALC holds the gain constant instead of amplifying the signal towards the target threshold. The NAU88C22 accomplishes this by comparing the input signal level against the noise gate threshold. The noise gate only operates in conjunction with the ALC and only in Normal mode. The noise gate is asserted when: Equation 1: (Signal at ADC – PGA gain – MIC Boost gain) < NGTH (Noise Gate Threshold Level) NAU88C22 Datasheet Rev 0.6 Page 25 of 101 June, 2016 PGA Input PGA Output PGA Gain Figure 9: ALC Operation Without Noise Gate PGA Input Noise Gate Threshold PGA Output PGA Gain Figure 10: Noise Gate Operation NAU88C22 Datasheet Rev 0.6 Page 26 of 101 June, 2016 3.12 ALC Example with ALC Min/Max Limits and Noise Gate Operation Output Level The drawing below shows the effects of ALC operation over the full scale signal range. The drawing is color coded to be more clear as follows: Blue Original Input signal (linear line from zero to maximum) Green PGA gain value over time (inverse to signal in target range) Red Output signal (held to a constant value in target range) Input < noise ALC operation range gate threshold Target ALCSL -6dB Gain (Attenuation) Clipped at ALCMNGAIN -12dB +33dB 0dB PGA Gain -12dB -39dB -39dB -6dB +6dB Input Level Register Bits Name Value 32 7-8 ALCSEL 11 32 3-5 ALCMAXGAIN 111 32 0-2 ALCMINGAIN 33 0-3 ALCLVL 35 3 NGEN 1 35 0-2 NGTH 000 000 1011 Description ALC enabled both channels Max ALC gain @ 35.25dB Min ALC gain @ -12dB Target ALC gain @ -6dBFS Noise gate enabled Noise gate @ -39dB Figure 11: ALC Response Envelope 3.12.1 ALC Register Map Overview ALC can be enabled for either or both the left and right ADC channels. All ALC functions and mode settings are common to the left and right channels. When either the right or left PGA is disabled, the respective PGA will remain at the most recent gain value as set by the ALC. Registers that control the ALC features and functions are: R32 R33 R34 R35 R70 R70 R71 R76 R77 Enable left/right ALC functions; set maximum gain, minimum gain ALC hold time, ALC target signal level ALC limiter mode selection, attack parameters, decay parameters Enable noise gate, noise gate parameters Selection of signal level averaging options and ALC table options Realtime readout of left channel gain value in use by ALC (same as left in stereo operation) Realtime readout of right channel gain value in use by ALC (same as right in stereo operation) Realtime readout of input signal level from averaging peak-to-peak input signal detector Realtime readout of input signal level from averaging input signal peak detector The following table shows some of the ALC parameter values and their ranges. The complete list of settings and values is included in the Detailed Register Map. NAU88C22 Datasheet Rev 0.6 Page 27 of 101 June, 2016 Registe r Parameter Bits Name ALCMING AIN ALCMAX GAIN Default Programmable Range Setting Value 000 -12dB 111 35.25dB Minimum Gain of PGA 32 0-2 Maximum Gain of PGA 32 3-5 ALC Function 32 7-8 ALCEN 00 Disable d ALC Target Level 33 0-3 ALCLVL 1011 -6dBFS ALC Hold Time 33 4-7 ALCHLD 0000 0ms ALC Attack time 34 0-3 ALCATK 0010 500μs ALC Decay Time 34 4-7 ALCDCY 0011 4ms Limiter Function 34 8 ALCMODE 0 Disable d Range: -12dB to +30dB @ 6dB increments Range: -6.75dB to +35.25dB @ 6dB increments 00 = Disable 01 = Enable right channel 10 = Enable left channel 11 = Enable both channels Range: -22.5dB to -1.5dBFS @ 1.5dB increments Range: 0ms to 1024ms at 1010 and above (times are for 0.75dB steps, and double with every step) ALCM=0 - Range: 125μs to 128ms ALCM=1 - Range: 31μs to 32ms (times are for 0.75dB steps, and double with every step) ALCM = 0 - Range: 500μs to 512ms ALCM = 1 - Range: 125μs to 128ms (times are for 0.75dB steps, and double with every step) 0 = ALC mode 1 = Limiter mode Table 5: Registers associated with ALC and Limiter Control 3.13 Limiter Mode When register 34, bit 8, is HIGH and ALC is enabled in register 32, bits 7-8 (ALCEN), the ALC block operates in limiter mode. In this mode, the PGA gain is constrained to be less than or equal to the PGA gain setting when the limiter mode is enabled. In addition, attack and decay times are faster in limiter mode than in normal mode as indicated by the different lookup tables for these parameters for limiter mode. The following waveform illustrates the behavior of the ALC in limiter mode in response to changes in various ALC parameters. PGA Input PGA Output PGA Gain Limiter Enabled Figure 12: ALC Limiter Mode Operation NAU88C22 Datasheet Rev 0.6 Page 28 of 101 June, 2016 4 ADC Digital Block ADC Digital Filters ΣΔ ADC Digital Filter Gain 5-Band Equalizer High Pass Filter Digital Audio Interface Notch Filter The ADC digital block performs 24-bit analog-to-digital conversion and signal processing, making available a high quality audio sample stream the audio path digital interface. This block consists of a sigma-delta modulator, digital decimator/ filter, 5-band graphic equalizer, 3D effects, high pass filter, and a notch filter. The equalizer and 3D audio function block is a single resource that may be used by either the ADC or DAC, but not both at the same time. The ADC coding scheme is in twos complement format and the full-scale input level is proportional to VDDA. With a 3.3V supply voltage, the full-scale level is 1.0VRMS. Registers that affect the ADC operation are: R2 Power management enable/disable left/right ADC R5 Digital passthrough of ADC output data into DAC input R7 Sample rate indication bits (affect filter frequency scaling) R14 Oversampling, polarity inversion, and filter controls for left/right ADC R14 ADC high pass filter Audio Mode or Application Mode selection R15 Left channel ADC digital volume control and update bit function R16 Right channel ADC digital volume control and update bit function 4.1 Sampling / Oversampling Rate, Polarity Control, Digital Passthrough The audio sample rate of the ADC is determined entirely by the IMCLK internal Master Clock frequency, which is 128 times the base audio sample rate. A technique known as oversampling is used to improve noise and distortion performance of the ADC, but this does not affect the final audio sample rate. The default oversampling rate of the ADC is 64X (64 times the audio sample rate), but this can be changed to 128X for greatly improved audio performance. The higher rate increases power consumption by only approximately three milliwatts per channel, so for most applications, the improved quality is a good choice. There is almost zero increased power to also run the DACs at 128X oversampling, and the best overall quality will be achieved when both the DACs and ADCs are operated at the same oversampling rate. The polarity of either ADC output signal can be changed independently on either ADC logic output as a feature sometimes useful in management of the audio phase. This feature can help minimize any audio processing that may be otherwise required as the data are passed to other stages in the system. Digital audio passthrough allows the output of the ADCs to be directly sent to the DACs as the input signal to the DAC for DAC output. In this mode of operation, the output data from the ADCs are still available on the ADCOUT logic pin. However, any external input signal for the DAC will be ignored. The passthrough function is useful for many test and application purposes, and the DAC output may be utilized in any way that is normally supported for the DAC analog output signals. NAU88C22 Datasheet Rev 0.6 Page 29 of 101 June, 2016 4.2 ADC Digital Volume Control and Update Bit Functionality The effective output audio volume of each ADC can be changed using the digital volume control feature. This processes the output of the ADC to scale the output by the amount indicated in the volume register setting. Included is a “digital mute” value which will completely mute the signal output of the ADC. The digital volume setting can range from 0dB through -127dB in 0.5dB steps. Important: The R15 and R16 update bits are write-only bits. The primary intended purpose of the update bit is to enable simultaneous changes to both the left and right ADC volume values, even though these values must be written sequentially. When there is a write operation to either R15 or R16 volume settings, but the update bit is not set (value = 0), the new volume setting is stored as pending for the future, but does not go into effect. When there is a write operation to either R15 or R16 and the update bit is set (value = 1), then the new value in the register being written is immediately put into effect, and any pending value in the other ADC volume register is put into effect at the same time. 4.3 ADC Programmable High Pass Filter Each ADC is optionally supported by a high pass filter in the digital output path. Filter operation and settings are always the same for both left and right channels. The high pass filter has two different operating modes. In the audio mode, the filter is a simple first order DC blocking filter, with a cut-off frequency of 3.7Hz. In the application specific mode, the filter is a second order audio frequency filter, with a programmable cut-off frequency. The cutoff frequency of the high pass filter is scaled depending on the sampling frequency indicated to the system by the setting in Register 7. Registers that affect operation of the programmable high pass filter are: R7 Sample rate indication to the system (affects filter coefficient internal scaling) R14 High-pass enable/disable, operating mode, and cut-off frequency The following table provides the exact cutoff frequencies with different sample rates as indicated to the system by means of Register 7. The table shows the assumed actual numerical sample rates as determined by the system clocks. Detailed response curves are provided in the Appendix section of this document. Register 14, bits 4 to 6 (HPF) 000 001 010 011 100 101 110 111 R7(SMPLR) = 101 or 100 Sample Rate in kHz (FS) R7(SMPLR) = 011 or 010 R7(SMPLR) = 001 or 000 8 11.025 12 16 22.05 24 32 44.1 48 82 102 131 163 204 261 327 408 113 141 180 225 281 360 450 563 122 153 156 245 306 392 490 612 82 102 131 163 204 261 327 408 113 141 180 225 281 360 450 563 122 153 156 245 306 392 490 612 82 102 131 163 204 261 327 408 113 141 180 225 281 360 450 563 122 153 156 245 306 392 490 612 Table 6: High Pass Filter Cut-off Frequencies in Hz (with HPFAM register 14, bit 7 = 1) 4.4 Programmable Notch Filter Each ADC is optionally supported by a notch filter in the digital output path. Filter operation and settings are always the same for both left and right channels. A notch filter is useful to a very narrow band of audio frequencies in a stop band around a given center frequency. The notch filter is enabled by setting register 27, bit 7 (NFCEN), to 1. The center frequency is programmed by setting registers 27, 28, 29, and 30, bits 0 to 6 (NFA0[13:7], NFA0[6:0], NFA1[13:7], NFA1[6:0]), with two’s compliment coefficient values calculated using table __. Registers that affect operation of the notch filter are: NAU88C22 Datasheet Rev 0.6 Page 30 of 101 June, 2016 R27 R27 R28 R29 R30 Notch filter enable/disable Notch filter a0 coefficient high order bits and update bit Notch filter a0 coefficient low order bits and update bit Notch filter a1 coefficient high order bits and update bit Notch filter a1 coefficient low order bits and update bit Important: The register update bits are write-only bits. The update bit function is important so that all filter coefficients actively being used are changed simultaneously, even though these register values must be written sequentially. When there is a write operation to any of the filter coefficient settings, but the update bit is not set (value = 0), the value is stored as pending for the future, but does not go into effect. When there is a write operation to any coefficient register, and the update bit is set (value = 1), then the new value in the register being written is immediately put into effect, and any pending coefficient value is put into effect at the same time. Coefficient values are in the form of 2’s-complement integer values, and must be calculated based upon the desired filter properties. The mathematical operations for calculating these coefficients are detailed in the following table. A0  2  fb   1  tan   2 f  s    2  fb   1  tan   2 f  s   A1 Notation Register Value (DEC) NFCA0 = -A0 x 213  1  A0   2  fc   x cos   fs   fc = center frequency (Hz) fb = -3dB bandwidth (Hz) fs = sample frequency (Hz) NFCA1 = -A1 x 212 Note: Values are rounded to the nearest whole number and converted to 2’s complement Table 7: Equations to calculate notch filter coefficients NAU88C22 Datasheet Rev 0.6 Page 31 of 101 June, 2016 5 DAC Digital Block DAC Digital Filters Digital Audio Interface Digital Gain 5-Band Equalizer 3D Digital Peak Limiter ΣΔ DAC Digital Filter The DAC digital block uses 24-bit signal processing to generate analog audio with a 16-bit digital sample stream input. This block consists of a sigma-delta modulator, digital decimator/filter, and optional 5-band graphic equalizer/3D effects block, and a dynamic range compressor/limiter. The DAC coding scheme is in twos complement format and the full-scale output level is proportional to VDDA. With a 3.3V supply voltage, the full-scale output level is 1.0VRMS. Registers that affect the DAC operation are: R3 Power management enable/disable left/right DAC R5 Digital passthrough of ADC output data into DAC input R7 Sample rate indication bits (affect filter frequency scaling) R10 Softmute, Automute, oversampling options, polarity controls for left/right DAC R11 Left channel DAC digital volume value; update bit feature R12 Right channel DAC digital volume value; update bit feature 5.1 DAC Soft Mute Both DACs are initialized with the SoftMute function disabled, which is a shared single control bit. Softmute automatically ramps the DAC digital volume down to zero volume when enabled, and automatically ramps the DAC digital volume up to the register specified volume level for each DAC when disabled. This feature provides a tool that is useful for using the DACs without introducing pop and click sounds. 5.2 DAC AutoMute The analog output of both DACs can be automatically muted in a no signal condition. Both DACs share a single control bit for this function. When automute is enabled, the analog output of the DAC will be muted any time there are 1024 consecutive audio sample values with a zero value. If at any time there is a non-zero sample value, the DAC will be un-muted, and the 1024 count will be reinitialized to zero. 5.3 DAC Sampling / Oversampling Rate, Polarity Control, Digital Passthrough The sampling rate of the DAC is determined entirely by the frequency of its input clock and the oversampling rate setting. The oversampling rate of the DAC can be changed to 128X for improved audio performance at slightly higher power consumption. Because the additional supply current is only 1mA, in most applications the 128X oversampling is preferred for maximum audio performance. The polarity of either DAC output signal can be changed independently on either DAC analog output as a feature sometimes useful in management of the audio phase. This feature can help minimize any audio processing that may be otherwise required as the data are passed to other stages in the system. Digital audio passthrough allows the output of the ADCs to be directly sent to the DACs as the input signal to the DAC for DAC output. In this mode of operation, the external digital audio signal for the DAC will be NAU88C22 Datasheet Rev 0.6 Page 32 of 101 June, 2016 ignored. The passthrough function is useful for many test and application purposes, and the DAC output may be utilized in any way that is normally supported for the DAC analog output signals. 5.4 DAC Digital Volume Control and Update Bit Functionality The effective output audio volume of each DAC can be changed using the digital volume control feature. This processes the output of the DAC to scale the output by the amount indicated in the volume register setting. Included is a “digital mute” value which will completely mute the signal output of the DAC. The digital volume setting can range from 0dB through -127dB in 0.5dB steps. Important: The R11 and R12 update bits are write-only bits. The primary intended purpose of the update bit is to enable simultaneous changes to both the left and right DAC volume values, even though these values must be written sequentially. When there is a write operation to either R11 or R12 volume settings, but the update bit is not set (value = 0), the new volume setting is stored as pending for the future, but does not go into effect. When there is a write operation to either R11 or R12 and the update bit is set (value = 1), then the new value in the register being written is immediately put into effect, and any pending value in the other DAC volume register is put into effect at the same time. 5.5 DAC Automatic Output Peak Limiter / Volume Boost Both DACs are supported by a digital output volume limiter/boost feature which can be useful to keep output levels within a desired range without any host/processor intervention. Settings are shared by both DAC channels. Registers that manage the peak limiter and volume boost functionality are: R24 Limiter enable/disable, limiter attack rate, boost decay rate R25 Limiter upper limit, limiter boost value The operation of the peak limiter is shown in the following figure. The upper signal graphs show the time varying level of the input and output signals, and the lower graph shows the gain characteristic of the limiter. When the signal level exceeds the limiter threshold value by 0.5dB or greater, the DAC digital signal level will be attenuated at a rate set by the limiter attack rate value. When the input signal level is less than the boost lower limit by 0.5dB or greater, the DAC digital volume will be increased at a rate set by the boost decay rate value. The default boost gain value is limited not to exceed 0dB (zero attenuation). DAC Input Signal Envelope DAC Output Signal Envelope Threshold -1dB 0dB -0.5dB -1dB Digital Gain Figure 13: DAC Digital Limiter Control The limiter may optionally be set to automatically boost the DAC digital signal level when the signal is more than 0.5dB below the limiter threshold. This can be useful in applications in which it is desirable to compress the signal dynamic range. This is accomplished by setting the limiter boost register bits to a value greater than zero. If the limiter is disabled, this boost value will be applied to the DAC digital output signal separate from other gain affecting values. NAU88C22 Datasheet Rev 0.6 Page 33 of 101 June, 2016 5.6 5-Band Equalizer The NAU88C22 includes a 5-band graphic equalizer with low distortion, low noise, and wide dynamic range. The equalizer is applied to both left and right channels. The equalizer is grouped with the 3D Stereo Enhancement signal processing function. Both functions may be assigned to support either the ADC path, or the DAC path, but not both paths simultaneously. Registers that affect operation of the 5-Band Equalizer are: R18 R18 R19 R20 R21 R22 Assign equalizer to DAC path or to ADC path (default = ADC path) Band 1 gain control and cut-off frequency Band 2 gain control, center cut-off frequency, and bandwidth Band 3 gain control, center cut-off frequency, and bandwidth Band 4 gain control, center cut-off frequency, and bandwidth Band 5 gain control and cut-off frequency Each of the five equalizer bands is independently adjustable for maximum system flexibility, and each offers up to 12dB of boost and 12dB of cut with 1dB resolution. The high and the low bands are shelving filters (highpass and low-pass, respectively), and the middle three bands are peaking filters. Details of the register value settings are described below. Response curve examples are provided in the Appendix of this document. Register Value 00 01 10 11 1 (High Pass) Register 18 Bits 5 & 6 EQ1CF 80Hz 105Hz 135Hz 175Hz 2 (Band Pass) Register 19 Bits 5 & 6 EQ2CF 230Hz 300Hz 385Hz 500Hz Equalizer Band 3 (Band Pass) Register 20 Bits 5 & 6 EQ3CF 650Hz 850Hz 1.1kHz 1.4kHz 4 (Band Pass) Register 21 Bits 5 & 6 EQ4CF 1.8kHz 2.4kHz 3.2kHz 4.1kHz 5 (Low Pass) Register 22 Bits 5 & 6 EQ5CF 5.3kHz 6.9kHz 9.0kHz 11.7kHz Table 8: Equalizer Center/Cutoff Frequencies Register Value Binary Hex 00000 00h 00001 01h 00010 02h ---01100 0Ch 01101 17h ---11000 18h 11001 to 11111 19h to 1Fh Gain Registers +12db +11dB +10dB Increments 1dB per step 0dB -11dB Increments 1dB per step -12dB Reserved Bits 0 to 4 in registers 18 (EQ1GC) 19 (EQ2GC) 20 (EQ3GC) 21 (EQ4GC) 22 (EQ5GC) Table 9: Equalizer Gains NAU88C22 Datasheet Rev 0.6 Page 34 of 101 June, 2016 5.7 3D Stereo Enhancement NAU88C22 includes digital circuitry to provide flexible 3D enhancement to increase the perceived separation between the right and left channels, and has multiple options for optimum acoustic performance. The equalizer is grouped with the 3D Stereo Enhancement signal processing function. Both functions may be assigned to support either the ADC path, or the DAC path, but not both paths simultaneously. Registers that affect operation of 3D Stereo Enhancement are: R18 Assign equalizer to DAC path or to ADC path (default = ADC path) R41 3D Audio depth enhancement setting The amount of 3D enhancement applied can be programmed from the default 0% (no 3D effect) to 100% in register 41, bits 0 to 3 (DEPTH3D), as shown in Table __. Note: 3D enhancement uses increased gain to achieve its effect, so that the source signal may need to be attenuated by up to 6dB to avoid clipping. Register 41 Bits 0 to 3 3DDEPTH 3D Effect 0000 0% 0001 0010 6.7%dB 13.4%dB --- Increments 6.67% for each binary step in the input word 1110 1111 93.3% 100% Table 10: 3D Enhancement Depth 5.8 Companding Companding is used in digital communication systems to optimize signal-to-noise ratios with reduced data bit rates, using non-linear algorithms. NAU88C22 supports the two main telecommunications companding standards on both the transmit and the receive sides: A-law and µ-law. The A-law algorithm is primarily used in European communication systems and the µ -law algorithm is primarily used by North America, Japan, and Australia. . Companding converts 13 bits (µ -law) or 12 bits (A-law) to 8 bits using non-linear quantization. The companded signal is an 8bit word containing sign (1-bit), exponent (3-bits) and mantissa (4-bits) Following are the data compression equations set in the ITU-T G.711 standard and implemented in the NAU88C22: 5.9 µ -law F(x) = ln( 1 + µ|x|) / ln( 1 + µ) -1 ≤ x ≤ 1 with µ=255 for the U.S. and Japan 5.10 A-law with A=87.6 for Europe The register affecting companding operation is: R5 Enable 8-bit mode, enable DAC companding, enable ADC companding The companded signal is an 8-bit word consisting of a sign bit, three bits for the exponent, and four bits for the mantissa. When companding is enabled, the PCM interface must be set to an 8-bit word length. When in 8-bit mode, the Register 4 word length control (WLEN) is ignored. NAU88C22 Datasheet Rev 0.6 Page 35 of 101 June, 2016 Companding Mode No Companding (default) ADC A-law μ-law DAC A-law μ-law Bit 4 0 Register 5 Bit3 Bit 2 0 0 1 1 1 1 Bit 1 0 1 0 1 0 Table 11: Companding Control 5.11 8-bit Word Length 6 Writing a 1 to register 5, bit 5 (CMB8), will cause the PCM interface to use 8-bit word length for data transfer, overriding the word length configuration setting in WLEN (register 4, bits 5 and 6.). NAU88C22 Datasheet Rev 0.6 Page 36 of 101 June, 2016 Analog Outputs The NAU88C22 features six different analog outputs. These are highly flexible and may be used individually or in pairs for many purposes. However, they are grouped in pairs and named for their most commonly used stereo application end uses. The following sections detail key features and functions of each type of output. Included is a description of the associated output mixers. These mixers are separate internal functional blocks that are important toward understanding all aspects of the analog output section. Important: For analog outputs depopping purpose, when powering up speakers, headphone, AUXOUTs, certain delays are generated after enabling sequence. However, the delays are created by MCLK and sample rate register. For correct operation, sending I2S signal no earlier than 250ms after speaker or headphone enabled and MCLK appearing. 6.1 Main Mixers (LMAIN MIX and RMAIN MIX) Each left and right channel is supported by an independent main mixer. This mixer combines signals from a various available signal sources internal to the device. Each mixer may also be selectively enabled/disabled as part of the power management features. The outputs of these mixers are the only signal source for the headphone outputs, and the primary signal source for the loudspeaker outputs. Each mixer can accept either or both the left and right digital to analog (DAC) outputs. Normally, the left and right DAC is mixed into the associated left and right main output mix. This additional capability to mix opposite DAC channels enables switching the left and right DAC outputs to the opposite channel, or mixing together the left and right DAC signals – all without any processor or host intervention and processing overhead. Each mixer also can also combine signals directly from the respective left or right AUX input, and from the output of the respective ADC Mix/Boost stage output. Each of these paths may be muted, or have an applied selectable gain between -15dB and +6dB in 3dB steps. Registers that affect operation of the Main Mixers are: R3 R49 R50 R51 R50 R51 6.2 Power control for the left and right main mixer left and right DAC cross-mixing source selection options left DAC to left main mixer source selection option right DAC to right main mixer source selection option left AUX and ADC Mix/Boost source select, and gain settings right AUX and ADC Mix/Boost source select, and gain settings Auxiliary Mixers (AUX1 MIXER and AUX2 MIXER) Each auxiliary analog output channel is supported by an independent mixer dedicated to the auxiliary output function. This mixer combines signals from a various available signal sources internal to the device. Each mixer may also be selectively enabled/disabled as part of the power management features. Unlike the main mixers, the auxiliary mixers are not identical and combine different signal sets internal to the device. These mixers in conjunction with the auxiliary outputs greatly increase the overall capabilities and flexibility of the NAU88C22. The AUX1 mixer combines together any or all of the following: Left Main Mixer output Right Main Mixer output Left DAC output Right DAC output Right ADC Mix/Boost stage output The AUX2 mixer combines together any or all of the following: Left Main Mixer output Left DAC output Left ADC Mix/Boost stage output Inverted output from AUX1 mixer stage NAU88C22 Datasheet Rev 0.6 Page 37 of 101 June, 2016 Registers that affect operation of the Auxiliary Mixers are: R1 Power control for the left and right auxiliary mixer R56 Signal source selection for the AUX2 mixer R57 Signal source selection for the AUX1 mixer 6.3 Right Speaker Submixer The right speaker submixer serves two important functions. One is to optionally invert the output from the Right Main Mixer as an optional signal source for the right channel loudspeaker output driver. This inversion is normal and necessary in typical applications using the loudspeaker drivers. The other function of the right speaker submixer is to mix the RAUXIN input signal directly into the right channel speaker output driver. This enables the RAUXIN signal to be output on the right loudspeaker channel, but not be mixed to any other output. The traditional purpose of this path is to support an old-style beep sound, such as traditionally generated by a microprocessor output toggle bit. On the NAU88C22, this traditional function is supported by a full quality signal path that may be used for any purpose. The volume for this path has a selectable gain from -15dB through +6dB in 3dB step increments. There is no separate power management control feature for the Right Speaker Submixer. The register that affects the Right Speaker Submixer is: R43 Input mute controls, volume for RAUXIN path 6.4 Headphone Outputs (LHP and RHP) These are high quality, high current output drivers intended for driving low impedance loads such as headphones, but also suitable for a wide range of audio output applications. The only signal source for each of these outputs is from the associated left and right Main Mixer. Power for this section is provided from the VDDA pin. Each driver may be selectively enabled/disabled as part of the power management features. Each output can be individually muted, or controlled over a gain range of -57dB through +6dB in 3dB steps. Gain changes for the two headphone outputs can be coordinated through use of an update bit feature as part of the register controls. Additionally, clicks that could result from gain changes can be suppressed using an optional zero crossing feature. Registers that affect the headphone outputs are: R2 Power management control for the left and right headphone amplifier R52 Volume, mute, update, and zero crossing controls for left headphone driver R53 Volume, mute, update, and zero crossing controls for right headphone driver Important: The R52 and R53 update bits are write-only bits. The primary intended purpose of the update bit is to enable simultaneous changes to both the left and right headphone output volume values, even though these two register values must be written sequentially. When there is a write operation to either R52 or R53 volume settings, but the update bit is not set (value = 0), the new volume setting is stored as pending for the future, but does not go into effect. When there is a write operation to either R52 or R53 and the update bit is set (value = 1), then the new value in the register being written is immediately put into effect, and any pending value in the other headphone output volume register is put into effect at the same time. Zero-Crossing controls are implemented to suppress clicking sounds that may occur when volume setting changes take place while an audio input signal is active. When the zero crossing function is enabled (logic = 1), any volume change for the affected channel will not take place until the audio input signal passes through the zero point in its peak-to-peak swing. This prevents any instantaneous voltage change to the audio signal caused by volume setting changes. If the zero crossing function is disabled (logic = 0), volume changes take place instantly on condition of the Update Bit, but without regard to the instantaneous voltage level of the affected audio input signal. NAU88C22 Datasheet Rev 0.6 Page 38 of 101 June, 2016 6.5 Speaker Outputs These are high current outputs suitable for driving low impedance loads, such as an 8-ohm loudspeaker. Both outputs may be used separately for a wide range of applications, however, the intended application is to use both outputs together in a BTL (Bridge-Tied-Load, and also, Balanced-Transformer-Less) configuration. In most applications, this configuration requires an additional signal inversion, which is a feature supported in the right speaker submixer block. This inversion is normal and necessary when the two speaker outputs are used together in a BTL (Bridge-TiedLoad, and also, Balanced-Transformer-Less) configuration. In this physical configuration, the RSPKOUT signal is connected to one pole of the loudspeaker, and the LSPKOUT signal is connected to the other pole of the loudspeaker. Mathematically, this creates within the loudspeaker a signal equal to (Left-Right). The desired mathematical operation for a stereo signal is to drive the speaker with (Left+Right). This is accomplished by implementing an additional inversion to the right channel signal. For most applications, best performance will be achieved when care is taken to insure that all gain and filter settings in both the left and right channel paths to the loudspeaker drivers are identical. Power for the loudspeaker outputs is supplied via the VDDSPK pin, and ground is independently provided as the VSSPK pin. This power option enables an operating voltage as high as 5Vdc and helps in a system design to prevent high current outputs from creating noise on other supply voltage rails or system grounds. VSSPK must be connected at some point in the system to VSSA, but provision of the VSSPK as a separate high current ground pin facilitates managing the flow of current to prevent “ground bounce” and other ground noise related problems. Each loudspeaker output may be selectively enabled/disabled as part of the power management features. Registers that affect the loudspeaker outputs are: R3 Power management control of LSPKOUT and RSPKOUT driver outputs R3 Speaker bias control (BIASGEN) set logic = 1 for maximum power and VDDSPK > 3.60Vdc R48 Driver distortion mode control R49 Disable boost control for speaker outputs for VDDSPK 3.3V or lower R54 Volume (gain), mute, update bit, and zero crossing control for left speaker driver R55 Volume (gain), mute, update bit, and zero crossing control for right speaker driver Important: The R49 boost control option is set in the power-on reset condition for high voltage operation of VDDSPK. If VDDSPK is greater than 3.6Vdc, the R49 boost control bits should be remain at the power-on default settings. This insures reliable operation of the part, proper DC biasing, and optimum scaling of the signal to enable the output to achieve full scale output when VDDSPK is greater than VDDA. In the boost mode, the gain of the output stage is increased by a factor of 1.5 times the normal gain value. Important: The R54 and R55 update bits are write-only bits. The primary intended purpose of the update bit is to enable simultaneous changes to both the left and right headphone output volume values, even though these two register values must be written sequentially. When there is a write operation to either R54 or R55 volume settings, but the update bit is not set (value = 0), the new volume setting is stored as pending for the future, but does not go into effect. When there is a write operation to either R54 or R55 and the update bit is set (value = 1), then the new value in the register being written is immediately put into effect, and any pending value in the other headphone output volume register is put into effect at the same time. Zero-Crossing controls are implemented to suppress clicking sounds that may occur when volume setting changes take place while an audio input signal is active. When the zero crossing function is enabled (logic = 1), any volume change for the affected channel will not take place until the audio input signal passes through the zero point in its peak-to-peak swing. This prevents any instantaneous voltage change to the audio signal caused by volume setting changes. If the zero crossing function is disabled (logic = 0), volume changes take place instantly on condition of the Update Bit, but without regard to the instantaneous voltage level of the affected audio input signal. The loudspeaker drivers may optionally be operated in an ultralow distortion mode. This mode may require additional external passive components to insure stable operation in some system configurations. No external components are required in normal mode speaker driver operation. Distortion performance in normal operation is excellent, and already suitable for almost every application. NAU88C22 Datasheet Rev 0.6 Page 39 of 101 June, 2016 Important: 4Ω equivalent loading speakers are not recommended to use for speaker outputs. NAU88C22 Datasheet Rev 0.6 Page 40 of 101 June, 2016 6.6 Auxiliary Outputs These are high current outputs suitable for driving low impedance loads such as headphones or line level loads. Power for these outputs is supplied via the VDDSPK pin, and ground is also independently provided as the VSSPK pin. This power option enables an operating voltage as high as 5Vdc and helps in a system design to prevent high current outputs from creating noise on other supply voltage rails or system grounds. VSSPK must be connected at some point in the system to VSSA, but provision of the VSSPK as a separate high current ground pin facilitates managing the flow of current to prevent “ground bounce” and other ground noise related problems. Each auxiliary output driver may be selectively enabled/disabled as part of the power management features. Registers that affect the auxiliary outputs are: R3 Power management control of AUXOUT1 and AUXOUT2 outputs R3 Speaker bias control (BIASGEN) set logic = 1 for maximum power and VDDSPK > 3.60Vdc R49 Disable boost control for AUXOUT1 and AUXOUT2 for VDDSPK 3.3Vdc or lower R56 Mute, gain control, and input selection controls for AUXOUT2 R57 Mute, gain control, and input selection controls for AUXOUT1 Important: The R49 boost control option is set in the power-on reset condition for high voltage operation of VDDSPK. If VDDSPK is greater than 3.6Vdc, the R49 boost control bits should be remain at the power-on default settings. This insures reliable operation of the part, proper DC biasing, and optimum scaling of the signal to enable the output to achieve full scale output when VDDSPK is greater than VDDA. In the boost mode, the gain of the output stage is increased by a factor of 1.5 times the normal gain value. An optional alternative function for these outputs is to provide a virtual ground for an external headphone device. This is for eliminating output capacitors for the headphone amplifier circuit in applications where this type of design is appropriate. In this type of application, the AUXOUT output is typically operated in the muted condition. In the muted condition, and with the output configured in the non-boost mode (also requiring that VDDSPK < 3.61Vdc), the AUXOUT output DC level will remain at the internal VREF level. This the same internal DC level as used by the headphone outputs. Because these DC levels are nominally the same, DC current flowing through the headphone in this mode of operation is minimized. Depending on the application, one or both of the auxiliary outputs may be used in this fashion. 7 Miscellaneous Functions 7.1 Slow Timer Clock An internal Slow Timer Clock is supplied to automatically control features that happen over a relatively periods of time, or time-spans. This enables the NAU88C22 to implement long time-span features without any host/processor management or intervention. Two features are supported by the Slow Timer Clock. These are an optional automatic time out for the zerocrossing holdoff of PGA volume changes, and timing for debouncing of the mechanical jack detection feature. If either feature is required, the Slow Timer Clock must be enabled. The Slow Timer Clock is initialized in the disabled state. The Slow Timer Clock is controlled by only the following register: R7 Sample rate indication select, and Slow Timer Clock enable The Slow Timer Clock rate is derived from MCLK using an integer divider that is compensated for the sample rate as indicated by the R7 sample rate register. If the sample rate register value precisely matches the actual sample rate, then the internal Slow Timer Clock rate will be a constant value of 128ms. If the actual sample rate is, for example, 44.1kHz and the sample rate selected in R7 is 48kHz, the rate of the Slow Timer Clock will be approximately 10% slower in direct proportion of the actual vs. indicated sample rate. This scale of difference should not be important in relation to the dedicated end uses of the Slow Timer Clock. NAU88C22 Datasheet Rev 0.6 Page 41 of 101 June, 2016 7.2 General Purpose Inputs and Outputs (GPIO1, GPIO2, GPIO3) and Jack Detection Three pins are provided in the NAU88C22 that may be used for limited logic input/output functions. GPIO1 has multiple possible functions, and may be either a logic input or logic output. GPIO2 and GPIO3 may be either line level analog inputs, or logic inputs dedicated to the purpose of jack detection. GPIO2 and GPIO3 do not have any logic output capability or function. Only one GPIO can be selected for jack detection. If a GPIO is selected for the jack detection feature, the Slow Timer Clock must be enabled. The jack detection function is automatically “debounced” such that momentary changes to the logic value of this input pin are ignored. The Slow Timer Clock is necessary for the debouncing feature. Registers that control the GPIO functionality are: R8 GPIO functional selection options R9 Jack Detection feature input selection and functional options If a GPIO is selected for the jack detection function, the required Slow Timer Clock determines the duration of the time windows for the input logic debouncing function. Because the logic level changes happen asynchronously to the Slow Timer Clock, there is inherently some variability in the timing for the jack detection function. A continuous and persistent logic change on the GPIO pin used for jack detection will result in a valid internal output signal within 2.5 to 3.5 periods of the Slow Timer Clock. Any logic change of shorter duration will be ignored. The threshold voltage for a jack detection logic-low level is no higher than 1.0Vdc. The threshold voltage for a jack detection logic-high level is no lower than 1.7Vdc. These levels will be reduced as the VDDC core logic voltage pin is reduced below 1.9Vdc. If the RLIN or LLIN input pin is used for the GPIO function, the analog signal path should be configured to be disconnected from its respective PGA input. This will not cause harm to the device, but could cause unwanted noise introduced through the PGA path. 7.3 Automated Features Linked to Jack Detection Some functionality can be automatically controlled by the jack detection logic. This feature can be used to enable the internal analog amplifier bias voltage generator, and/or enable analog output drivers automatically as a result of detecting a logic change at a GPIO pin assigned to the purpose of jack detection. This eliminates any requirement for the host/processor to perform these functions. The internal analog amplifier bias generator creates the VREF voltage reference and bias voltage used by the analog amplifiers. The ability to control it is a power management feature. This is implemented as a logical “OR” function of either the debounced internal jack detection signal, or the ABIASEN control bit in Register 1. The bias generator will be powered if either of these control signals is enabled (value = 1). Power management control of four different outputs is also optionally and selectively subject to control linked with the jack detection signal. The four outputs that can be controlled this way are the headphone driver signal pair, loudspeaker driver signal pair, AUXOUT1, and AUXOUT2. Register settings determine which outputs may be enabled, and whether they are enabled by a logic 1 or logic 0 value. Output control is a logical “AND” operation of the jack detection controls, and of the register control bits that normally control the outputs. Both controls must be in the “ON” condition for a given output to be enabled. Registers that affect these functions are: R9 GPIO pin selection for jack detect function, jack detection enable, VREF jack enable R13 bit mapped selection of which outputs are to be enabled when jack detect is in a logic 1 state R13 bit mapped selection of which outputs are to be enabled when jack detect is in a logic 0 state NAU88C22 Datasheet Rev 0.6 Page 42 of 101 June, 2016 8 Clock Selection and Generation The NAU88C22 has two basic clock modes that support the ADC and DAC data converters. It can accept external clocks in the slave mode, or in the master mode, it can generate the required clocks from an external reference frequency using an internal PLL (Phase Locked Loop). The internal PLL is a fractional type scaling PLL, and therefore, a very wide range of external reference frequencies can be used to create accurate audio sample rates. Separate from this ADC and DAC clock subsystem, audio data are clocked to and from the NAU88C22 by means of the control logic described in the Digital Audio Interfaces section. The audio bit rate and audio sample rate for this data flow are managed by the Frame Sync (FS) and Bit Clock (BCLK) pins in the Digital Audio Interface. It is important to understand that the sampling rate for the ADC and DAC data converters is not determined by the Digital Audio Interface, and instead, this rate is derived exclusively from the Internal Master Clock (IMCLK). It is therefore a requirement that the Digital Audio Interface and data converters be operated synchronously, and that the FS, BCLK, and IMCLK signals are all derived from a common reference frequency. If these three clocks signals are not synchronous, audio quality will be reduced. The IMCLK is always exactly 256 times the sampling rate of the data converters. Also note that IMCLK should not exceed 12.288MHz under any condition. IMCLK is output from the Master Clock Prescaler. The prescaler reduces by an integer division factor the input frequency input clock. The source of this input frequency clock is either the external MCLK pin, or the output from the internal PLL Block. Registers that are used to manage and control the clock subsystem are: R1 Power management, enable control for PLL (default = disabled) R6 Master/slave mode, clock scaling, clock selection R7 Sample rate indication (scales DSP coefficients and timing – does NOT affect actual sample rate R8 MUX control and division factor for PLL output on GPIO1 R36 PLL Prescaler, Integer portion of PLL frequency multiplier R37 Highest order bits of 24-bit fraction of PLL frequency multiplier R38 Middle order bits of 24-bit fraction of PLL frequency multiplier R39 Lowest order bits of 24-bit fraction of PLL frequency multiplier In Master Mode, the IMCLK signal is used to generate FS and BCLK signals that are driven onto the FS and BCLK pins and input to the Digital Audio Interface. FS is always IMCLK/256 and the duty cycle of FS is automatically adjusted to be correct for the mode selected in the Digital Audio Interface. The frequency of BCLK may optionally be divided to optimize the bit clock rate for the application scenario. In Slave Mode, there is no connection between IMCLK and the FS and BCLK pins. In this mode, FS and BLCK are strictly input pins, and it is the responsibility of the system designer to insure that FS, BCLK, and IMCLK are synchronous and scaled appropriately for the application. NAU88C22 Datasheet Rev 0.6 Page 43 of 101 June, 2016 R36[4] MCLK 0 f1 1 Master Clock Prescaler f2 PLL f2=R(f1) f/2 f/2 0 fPLL R6[7,6,5] 0 f/N R6[8] R8[2,1,0] 1 IMCLK = 256fS Master Clock Select PLL BLOCK GPIO1 MUX Control PLL49MOUT R72[2] && Master Clock Select R6[8] 1 f/2 CSB / GPIO1 DAC ADC PLL Prescaler BCLK Output Scaler f/N f/256 R6[4,3,2] f/N PLL to GPIO1 Output Scaler Master / Slave Select R8[5,4] R6[0] 1 0 FS Digital Audio Interface BCLK Figure 14: PLL and Clock Select Circuit 8.1 Phase Locked Loop (PLL) General Description The PLL may be optionally used to multiply an external input clock reference frequency by a high resolution fractional number. To enable the use of the widest possible range of external reference clocks, the PLL block includes an optional divide-by-two prescaler for the input clock, a fixed divide-by-four scaler on the PLL output, and an additional programmable integer divider that is the Master Clock Prescaler. The high resolution fraction for the PLL is the ratio of the desired PLL oscillator frequency (f 2), and the reference frequency at the PLL input (f1). This can be represented as R = f2/f1, with R in the form of a decimal number: xy.abcdefgh. To program the NAU88C22, this value is separated into an integer portion (“xy”), and a fractional portion, “abcdefgh”. The fractional portion of the multiplier is a value that when represented as a 24bit binary number (stored in three 9-bit registers on the NAU88C22), very closely matches the exact desired multiplier factor. To keep the PLL within its optimal operating range, the integer portion of the decimal number (“xy”), must be any of the following decimal values: 6, 7, 8, 9, 10, 11, or 12. The input and output dividers outside of the PLL are often helpful to scale frequencies as needed to keep the “xy” value within the required range. Also, the optimum PLL oscillator frequency is in the range between 90MHz and 100MHz, and thus, it is best to keep f 2 within this range. In order to operate in the 96kHz and 192kHz sampling modes, the following 3 bits need to set. 1. PLL49MOUT bit R72[2] 2. Master clock select bit R6[8]. 3. ADCB_OVER (ADC Bias current Override) R72[5] In summary, for any given design, choose:  IMCLK = desired Master Clock = (256)*(desired codec sample rate)  f2 = (4)*(P)(IMCLK), where P is the Master Clock Prescale integer value; optimal f 2: 90MHz< f2 0.546*fs dB 0.546 fs -60 dB Group Delay 28.25 1/fs -3dB 3.7 Hz -0.5dB 10.4 Hz -0.1dB 21.6 Hz ADC High Pass Filter High Pass Filter Corner Frequency DAC Filter Passband +/- 0.035dB 0 -6dB 0.454 0.5 Passband Ripple Stopband Attenuation fs +/-0.035 Stopband f > 0.546*fs fs dB 0.546 fs -55 dB Group Delay 28 1/fs Table 22: Digital Filter Characteristics TERMINOLOGY 1. Stop Band Attenuation (dB) – the degree to which the frequency spectrum is attenuated (outside audio band) 2. Pass-band Ripple – any variation of the frequency response in the pass-band region 3. Note that this delay applies only to the filters and does not include other latencies, such as from the serial data interface NAU88C22 Datasheet Rev 0.6 Page 67 of 101 June, 2016 Figure 38: DAC Filter Frequency Response Figure 39: DAC Filter Ripple Figure 40: ADC Filter Frequency Response NAU88C22 Datasheet Rev 0.6 Page 68 of 101 June, 2016 Figure 41: ADC Filter Ripple NAU88C22 Datasheet Rev 0.6 Page 69 of 101 June, 2016 0 -2 d B r -4 -6 10 20 30 Hz Figure 42: ADC Highpass Filter Response, Audio Mode 0 -20 d B -40 r -60 -80 100 300 500 700 900 Hz Figure 43: ADC Highpass Filter Response, HPF enabled, FS = 48kHz 0 -20 d B -40 r -60 -80 100 300 500 700 900 Hz Figure 44: ADC Highpass Filter Response, HPF enabled, FS = 24kHz 0 -20 d B -40 r -60 -80 100 300 500 700 900 Hz Figure 45: ADC Highpass Filter Response, HPF enabled, FS = 12kHz NAU88C22 Datasheet Rev 0.6 Page 70 of 101 June, 2016 +15 +10 +5 d B r 0 -5 -10 -15 20 50 100 200 500 1k 2k 5k 10k 20k Hz Figure 46: EQ Band 1 Gains for Lowest Cut-Off Frequency +15 +10 +5 d B r 0 -5 -10 -15 20 50 100 200 500 1k 2k 5k 10k 20k Hz Figure 47: EQ Band 2 Peak Filter Gains for Lowest Cut-Off Frequency with EQ2BW = 0 +15 +10 +5 d B r 0 -5 -10 -15 20 50 100 200 500 1k 2k 5k 10k 20k 10k 20k Hz Figure 48: EQ Band 2, EQ2BW = 0 versus EQ2BW = 1 +15 +10 +5 d B r 0 -5 -10 -15 20 50 100 200 500 1k 2k 5k Hz Figure 49: EQ Band 3 Peak Filter Gains for Lowest Cut-Off Frequency with EQ3BW = 0 NAU88C22 Datasheet Rev 0.6 Page 71 of 101 June, 2016 +15 +10 +5 d B r 0 -5 -10 -15 20 50 100 200 500 1k 2k 5k 10k 20k Hz Figure 50: EQ Band 3, EQ3BW = 0 versus EQ3BW = 1 +15 T +10 +5 d B r 0 -5 -10 -15 Figure 51: EQ Band 4 Peak Filter Gains for Lowest Cut-Off Frequencies with EQ4BW = 0 +15 +10 +5 d B r 0 -5 -10 -15 20 50 100 200 500 1k 2k 5k 10k 20k 10k 20k Hz Figure 52: EQ Band 4, EQ4BW = 0 versus EQ4BW =1 +15 +10 +5 d B r 0 -5 -10 -15 20 50 100 200 500 1k 2k 5k Hz Figure 53: EQ Band 5 Gains for Lowest Cut-Off Frequency NAU88C22 Datasheet Rev 0.6 Page 72 of 101 June, 2016 13 Appendix B: Companding Tables 13.1 µ-Law / A-Law Codes for Zero and Full Scale µ-Law Level A-Law Sign bit (D7) Chord bits (D6,D5,D4) Step bits (D3,D2,D1,D0) Sign bit (D7) Chord bits (D6,D5,D4) Step bits (D3,D2,D1,D0) + Full Scale 1 000 0000 1 010 1010 + Zero 1 111 1111 1 101 0101 - Zero 0 111 1111 0 101 0101 - Full Scale 0 000 0000 0 010 1010 Table 23: Companding Codes for Zero and Full-Scale 13.2 µ-Law / A-Law Output Codes (Digital mW) µ-Law Sample A-Law Sign bit (D7) Chord bits (D6,D5,D4) Step bits (D3,D2,D1,D0) Sign bit (D7) Chord bits (D6,D5,D4) Step bits (D3,D2,D1,D0) 1 0 001 1110 0 011 0100 2 0 000 1011 0 010 0001 3 0 000 1011 0 010 0001 4 0 001 1110 0 011 0100 5 1 001 1110 1 011 0100 6 1 000 1011 1 010 0001 7 1 000 1011 1 010 0001 8 1 001 1110 1 011 0100 Table 24: Companding Output Codes NAU88C22 Datasheet Rev 0.6 Page 73 of 101 June, 2016 14 Appendix C: Details of Register Operation Register Function Name Dec Hex 0 00 Bit Description 8 7 6 54 3 2 1 0 Any write operation to this register resets all registers to default values Software Reset Power control for internal tie-off buffer used in 1.5X boost conditions 0 = internal buffer unpowered 1 = enabled Power control for AUX1 MIXER supporting AUXOUT1 analog output 0 = unpowered 1 = enabled Power control for AUX2 MIXER supporting AUXOUT2 analog output 0 = unpowered 1 = enabled Power control for internal PLL 0 = unpowered 1 = enabled Power control for microphone bias buffer amplifier (MICBIAS output, pin#32) 0 = unpowered and MICBIAS pin in high-Z condition 1 = enabled Power control for internal analog bias buffers 0 = unpowered 1 = enabled Power control for internal tie-off buffer used in non-boost mode (-1.0x gain) conditions 0 = internal buffer unpowered 1 = enabled Select impedance of reference string used to establish VREF for internal bias buffers 00 = off (input to internal bias buffer in high-Z floating condition) 01 = 80kΩ nominal impedance at VREF pin 10 = 300kΩ nominal impedance at VREF pin 11 = 3kΩ nominal impedance at VREF pin DCBUFEN AUX1MXEN AUX2MXEN PLLEN 1 01 Power Management 1 MICBIASEN ABIASEN IOBUFEN REFIMP Default >> 0 0 0 00 0 0 0 0 RHPEN LHPEN SLEEP RBSTEN 2 02 Power Management 2 LBSTEN RPGAEN LPGAEN RADCEN LADCEN Default >> 0x000 reset value Right Headphone driver enable, RHP analog output, pin#29 0 = RHP pin in high-Z condition 1 = enabled Left Headphone driver enabled, LHP analog output pin#30 0 = LHP pin in high-Z condition 1 = enabled Sleep enable 0 = device in normal operating mode 1 = device in low-power sleep condition Right channel input mixer, RADC Mix/Boost stage power control 0 = RADC Mix/Boost stage OFF 1 = RADC Mix/Boost stage ON Left channel input mixer, LADC Mix/Boost stage power control 0 = LADC Mix/Boost stage OFF 1 = LADC Mix/Boost stage ON Right channel input programmable amplifier (PGA) power control 0 = Right PGA input stage OFF 1 = enabled Left channel input programmable amplifier power control 0 = Left PGA input stage OFF 1 = enabled Right channel analog-to-digital converter power control 0 = Right ADC stage OFF 1 = enabled Left channel analog-to-digital converter power control 0 = Left ADC stage OFF 1 = enabled 0 0 0 00 0 0 NAU88C22 Datasheet Rev 0.6 0 0 0x000 reset value Page 74 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 AUXOUT1 analog output power control, pin#21 0 = AUXOUT1 output driver OFF 1 = enabled AUXOUT2 analog output power control, pin#22 0 = AUXOUT2 output driver OFF 1 = enabled LSPKOUT left speaker driver power control, pin#25 0 = LSPKOUT output driver OFF 1 = enabled RSPKOUT left speaker driver power control, pin#23 0 = RSPKOUT output driver OFF 1 = enabled AUXOUT1EN AUXOUT2EN LSPKEN RSPKEN 3 03 Power Management 3 Reserved Reserved Right main mixer power control, RMAIN MIXER internal stage 0 = RMAIN MIXER stage OFF 1 = enabled Left main mixer power control, LMAIN MIXER internal stage 0 = LMAIN MIXER stage OFF 1 = enabled Right channel digital-to-analog converter, RDAC, power control 0 = RDAC stage OFF 1 = enabled Left channel digital-to-analog converter, LDAC, power control 0 = LDAC stage OFF 1 = enabled RMIXEN LMIXEN RDACEN LDACEN Default >> 0 0 0 00 0 0 0 0 BCLKP LRP WLEN 4 04 Audio Interface AIFMT DACPHS ADCPHS MONO Default >> 0x000 reset value Bit clock phase inversion option for BCLK, pin#8 0 = normal phase 1 = input logic sense inverted Phase control for I2S audio data bus interface 0 = normal phase operation 1 = inverted phase operation PCMA and PCMB left/right word order control 0 = MSB is valid on 2nd rising edge of BCLK after rising edge of FS 1 = MSB is valid on 1st rising edge of BCLK after rising edge of FS Word length (24-bits default) of audio data stream 00 = 16-bit word length 01 = 20-bit word length 10 = 24-bit word length 11 = 32-bit word length Audio interface data format (default setting is I2S) 00 = right justified 01 = left justified 10 = standard I2S format 11 = PCMA or PCMB audio data format option DAC audio data left-right ordering 0 = left DAC data in left phase of LRP 1 = left DAC data in right phase of LRP (left-right reversed) ADC audio data left-right ordering 0 = left ADC data is output in left phase of LRP 1 = left ADC data is output in right phase of LRP (left-right reversed) Mono operation enable 0 = normal stereo mode of operation 1 = mono mode with audio data in left phase of LRP 0 0 1 01 0 0 NAU88C22 Datasheet Rev 0.6 0 0 0x050 reset value Page 75 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Reserved 8-bit word enable for companding mode of operation 0 = normal operation (no companding) 1 = 8-bit operation for companding mode DAC companding mode control 00 = off (normal linear operation) 01 = reserved 10 = u-law companding 11 = A-law companding ADC companding mode control 00 = off (normal linear operation) 01 = reserved 10 = u-law companding 11 = A-law companding DAC audio data input option to route directly to ADC data stream 0 = no passthrough, normal operation 1 = ADC output data stream routed to DAC input data path CMB8 DACCM 5 05 Companding ADCCM ADDAP Default >> 0 0 0 00 0 0 0 0 CLKM MCLKSEL 6 06 0x000 reset value master clock source selection control 0 = MCLK, pin#11 used as master clock 1 = internal PLL oscillator output used as master clock Scaling of master clock source for internal 256fs rate ( divide by 2 = default) 000 = divide by 1 001 = divide by 1.5 010 = divide by 2 011 = divide by 3 100 = divide by 4 101 = divide by 6 110 = divide by 8 111 = divide by 12 Scaling of output frequency at BCLK pin#8 when chip is in master mode 000 = divide by 1 001 = divide by 2 010 = divide by 4 011 = divide by 8 100 = divide by 16 101 = divide by 32 110 = reserved 111 = reserved Clock control 1 BCLKSEL Reserved Enables chip master mode to drive FS and BCLK outputs 0 = FS and BCLK are inputs 1 = FS and BCLK are driven as outputs by internally generated clocks CLKIOEN Default >> 1 0 1 00 0 0 0 0 4WSPIEN 0x140 reset value 4-wire control interface enable Reserved 7 07 Clock control 2 Audio data sample rate indication (48kHz default). Sets up scaling for internal filter coefficients, but does not affect in any way the actual device sample rate. Should be set to value most closely matching the actual sample rate determined by 256fs internal node. 000 = 48kHz 001 = 32kHz 010 = 24kHz 011 = 16kHz 100 = 12kHz 101 = 8kHz 110 = reserved 111 = reserved Slow timer clock enable. Starts internal timer clock derived by dividing master clock. 0 = disabled 1 = enabled SMPLR SCLKEN Default >> 0 0 0 00 0 0 NAU88C22 Datasheet Rev 0.6 0 0 0x000 reset value Page 76 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Reserved Clock divisor applied to PLL clock for output from a GPIO pin 00 = divide by 1 01 = divide by 2 10 = divide by 3 11 = divide by 4 GPIO1 polarity inversion control 0 = normal logic sense of GPIO signal 1 = inverted logic sense of GPIO signal CSB/GPIO1 function select (input default) 000 = use as input subject to MODE pin#18 input logic level 001 = reserved 010 = Temperature OK status output ( logic 0 = thermal shutdown) 011 = DAC automute condition (logic 1 = one or both DACs automuted) 100 = output divided PLL clock 101 = PLL locked condition (logic 1 = PLL locked) 110 = output set to logic 1 condition 111 = output set to logic 0 condition GPIO1PLL GPIO1PL 8 08 GPIO GPIO1SEL Default >> 0 0 0 00 0 0 0 0 JCKMIDEN JACDEN 9 09 0x000 reset value Automatically enable internal bias amplifiers on jack detection state as sensed through GPIO pin associated to jack detection function Bit 7 = logic 1: enable bias amplifiers on jack at logic 0 level Bit 8 = logic 1: enable bias amplifiers on jack at logic 1 level Jack detection feature enable 0 = disabled 1 = enable jack detection associated functionality Select jack detect pin (GPIO1 default) 00 = GPIO1 is used for jack detection feature 01 = GPIO2 is used for jack detection feature 10 = GPIO3 is used for jack detection feature 11 = reserved Jack detect 1 JCKDIO Reserved Default >> 0 0 0 00 0 0 0 0 0x000 reset value Reserved Softmute feature control for DACs 0 = disabled 1 = enabled SOFTMT Reserved DAC oversampling rate selection (64X default) 0 = 64x oversampling 1 = 128x oversampling DAC automute function enable 0 = disabled 1 = enabled DAC right channel output polarity control 0 = normal polarity 1 = inverted polarity DAC left channel output polarity control 0 = normal polarity 1 = inverted polarity DACOS 10 0A DAC control AUTOMT RDACPL LDACPL Default >> 0 0 0 00 0 0 0 0 LDACVU 11 0B Left DAC volume LDACGAIN Default >> 0x000 reset value DAC volume update bit feature. Write-only bit for synchronized L/R DAC changes If logic = 0 on R11 write, new R11 value stored in temporary register If logic = 1 on R11 write, new R11 and pending R12 values become active DAC left digital volume control (0dB default attenuation value). Expressed as an attenuation value in 0.5dB steps as follows: 0000 0000 = digital mute condition 0000 0001 = -127.0dB (highly attenuated) 0000 0010 = -126.5dB attenuation - all intermediate 0.5 step values through maximum – 1111 1110 = -0.5dB attenuation 1111 1111 = 0.0dB attenuation (no attenuation) 0 1 1 11 1 1 NAU88C22 Datasheet Rev 0.6 1 1 0x0FF reset value Page 77 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 DAC volume update bit feature. Write-only bit for synchronized L/R DAC changes If logic = 0 on R12 write, new R12 value stored in temporary register If logic = 1 on R12 write, new R12 and pending R11 values become active DAC right digital volume control (0dB default attenuation value). Expressed as an attenuation value in 0.5dB steps as follows: 0000 0000 = digital mute condition 0000 0001 = -127.0dB (highly attenuated) 0000 0010 = -126.5dB attenuation - all intermediate 0.5 step values through maximum volume – 1111 1110 = -0.5dB attenuation 1111 1111 = 0.0dB attenuation (no attenuation) RDACVU 12 0C Right DAC volume RDACGAIN Default >> 0 1 1 11 1 1 1 1 0x0FF reset value Reserved Outputs drivers that are automatically enabled whenever the designated jack detection input is in the logic = 1 condition, and the jack detection feature is enabled Bit 4 = 1: enable Left and Right Headphone output drivers Bit 5 = 1: enable Left and Right Speaker output drivers Bit 6 = 1: enable AUXOUT2 output driver Bit 7 = 1: enable AUXOUT1 output driver Outputs drivers that are automatically enabled whenever the designated jack detection input is in the logic = 0 condition, and the jack detection feature is enabled Bit 0 = 1: enable Left and Right Headphone output drivers Bit 1 = 1: enable Left and Right Speaker output drivers Bit 2 = 1: enable AUXOUT2 output driver Bit 3 = 1: enable AUXOUT1 output driver JCKDOEN1 13 0D Jack detect 2 JCKDOEN0 Default >> 0 0 0 00 0 0 0 0 HPFEN HPFAM HPF 14 0E ADC control 0x000 reset value High pass filter enable control for filter of ADC output data stream 0 = high pass filter disabled 1 = high pass filter enabled High pass filter mode selection 0 = normal audio mode, 1st order 3.7Hz high pass filter for DC blocking 1 = application specific mode, variable 2nd order high pass filter Application specific mode cutoff frequency selection ADC oversampling rate selection (64X default) 0 = 64x oversampling rate for reduced power 1 = 128x oversampling for better SNR ADCOS Reserved ADC right channel polarity control 0 = normal polarity 1 = sign of RADC output is inverted from normal polarity ADC left channel polarity control 0 = normal polarity 1 = sign of LADC output is inverted from normal polarity RADCPL LADCPL Default >> 1 0 0 00 0 0 0 0 LADCVU 15 0F Left ADC volume LADCGAIN Default >> 0x100 reset value ADC volume update bit feature. Write-only bit for synchronized L/R ADC changes If logic = 0 on R15 write, new R15 value stored in temporary register If logic = 1 on R15 write, new R15 and pending R16 values become active ADC right digital volume control (0dB default attenuation value). Expressed as an attenuation value in 0.5dB steps as follows: 0000 0000 = digital mute condition 0000 0001 = -127.0dB (highly attenuated) 0000 0010 = -126.5dB attenuation - all intermediate 0.5 step values through maximum volume – 1111 1110 = -0.5dB attenuation 1111 1111 = 0.0dB attenuation (no attenuation) 0 1 1 11 1 1 NAU88C22 Datasheet Rev 0.6 1 1 0x0FF reset value Page 78 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 ADC volume update bit feature. Write-only bit for synchronized L/R ADC changes If logic = 0 on R16 write, new R16 value stored in temporary register If logic = 1 on R16 write, new R16 and pending R15 values become active ADC left digital volume control (0dB default attenuation value). Expressed as an attenuation value in 0.5dB steps as follows: 0000 0000 = digital mute condition 0000 0001 = -127.0dB (highly attenuated) 0000 0010 = -126.5dB attenuation - all intermediate 0.5 step values through maximum volume – 1111 1110 = -0.5dB attenuation 1111 1111 = 0.0dB attenuation (no attenuation) RADCVU 16 10 Right ADC volume 17 11 Reserved RADCGAIN Default >> 0 1 1 11 1 1 1 1 0x0FF reset value Equalizer and 3D audio processing block assignment. 0 = block operates on digital stream from ADC 1 = block operates on digital stream to DAC (default on reset) EQM Reserved Equalizer band 1 low pass -3dB cut-off frequency selection 00 = 80Hz 01 = 105Hz (default) 10 = 135Hz 11 = 175Hz EQ Band 1 digital gain control. Expressed as a gain or attenuation in 1dB steps 01100 = 0.0dB default unity gain value EQ1CF 18 12 EQ1 low cutoff 00000 = +12dB 00001 = +11dB - all intermediate 1.0dB step values through minimum gain 11000 = -12dB 11001 and larger values are reserved EQ1GC Default >> 1 0 0 10 1 1 0 0 0x12C reset value Equalizer Band 2 bandwidth selection 0 = narrow band characteristic (default) 1 = wide band characteristic EQ2BW Reserved Equalizer Band 2 center frequency selection 00 = 230Hz 01 = 300Hz (default) 10 = 385Hz 11 = 500Hz EQ Band 2 digital gain control. Expressed as a gain or attenuation in 1dB steps 01100 = 0.0dB default unity gain value EQ2CF 19 13 EQ2 - peak 1 00000 = +12dB 00001 = +11dB - all intermediate 1.0dB step values through minimum gain 11000 = -12dB 11001 and larger values are reserved EQ2GC Default >> 0 0 0 10 1 1 0 0 0x02C reset value Equalizer Band 3 bandwidth selection 0 = narrow band characteristic (default) 1 = wide band characteristic EQ3BW Reserved Equalizer Band 3 center frequency selection 00 = 650Hz 01 = 850Hz (default) 10 = 1.1kHz 11 = 1.4kHz EQ Band 3 digital gain control. Expressed as a gain or attenuation in 1dB steps 01100 = 0.0dB default unity gain value EQ3CF 20 14 EQ3 - peak 2 00000 = +12dB 00001 = +11dB - all intermediate 1.0dB step values through minimum gain 11000 = -12dB 11001 and larger values are reserved EQ3GC Default >> 0 0 0 10 1 1 NAU88C22 Datasheet Rev 0.6 0 0 0x02C reset value Page 79 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Equalizer Band 4 bandwidth selection 0 = narrow band characteristic (default) 1 = wide band characteristic EQ4BW Reserved Equalizer Band 4 center frequency selection 00 = 1.8kHz 01 = 2.4kHz (default) 10 = 3.2kHz 11 = 4.1kHz EQ Band 4 digital gain control. Expressed as a gain or attenuation in 1dB steps 01100 = 0.0dB default unity gain value EQ4CF 21 15 EQ4 - peak 3 00000 = +12dB 00001 = +11dB - all intermediate 1.0dB step values through minimum gain 11000 = -12dB 11001 and larger values are reserved EQ4GC Default >> 0 0 0 10 1 1 0 0 0x02C reset value Reserved Equalizer Band 5 high pass -3dB cut-off frequency selection 00 = 5.3kHz 01 = 6.9kHz (default) 10 = 9.0kHz 11 = 11.7kHz EQ Band 5 digital gain control. Expressed as a gain or attenuation in 1dB steps 01100 = 0.0dB default unity gain value EQ5CF 22 16 EQ5 - high cutoff 00000 = +12dB 00001 = +11dB - all intermediate 1.0dB step values through minimum gain 11000 = -12dB 11001 and larger values are reserved EQ5GC Default >> 23 17 0 0 0 10 1 1 0 0 Reserved DAC digital limiter control bit 0 = disabled 1 = enabled DAC limiter decay time. Proportional to actual DAC sample rate. Duration doubles with each binary bit value. Values given here are for 44.1kHz sample rate 0000 = 0.544ms 0001 = 1.09ms 0010 = 2.18ms 0011 = 4.36ms (default) 0100 = 8.72ms 0101 = 17.4ms 0110 = 34.8ms 0111 = 69.6ms 1000 = 139ms 1001 = 278ms 1010 = 566ms 1011 through 1111 = 1130ms DACLIMEN DACLIMDCY 24 18 DAC limiter 1 DAC limiter attack time. Proportional to actual DAC sample rate. Duration doubles with each binary bit value. Values given here are for 44.1kHz sample rate 0000 = 68.0us (microseconds) 0001 = 136us 0010 = 272us (default) 0011 = 544us 0100 = 1.09ms (milliseconds) 0101 = 2.18ms 0110 = 4.36ms 0111 = 8.72ms 1000 = 17.4ms 1001 = 34.8ms 1010 = 69.6ms 1011 through 1111 = 139ms DACLIMATK Default >> 25 19 0x02C reset value 0 0 0 11 0 0 DAC limiter NAU88C22 Datasheet Rev 0.6 1 0 0x032 reset value Reserved Page 80 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 DAC limiter threshold in relation to full scale output level (0.0dB = full scale) 000 = -1.0dB 001 = -2.0dB 010 = -3.0dB 011 = -4.0dB 100 = -5.0dB 101 through 111 = -6.0dB DAC limiter maximum automatic gain boost in limiter mode. If R24 limiter mode is disabled, specified gain value will be applied in addition to other gain values in the signal path. 0000 = 0.0dB (default) 0001 = +1.0dB - Gain value increases in 1.0dB steps for each binary value – 1100 = +12dB (maximum allowed boost value) 1101 through 1111 = reserved 2 DACLIMTHL DACLIMBST Default >> 26 1A 0 0 0 00 0 0 0 0 Update bit feature for simultaneous change of all notch filter parameters. Write-only bit. Logic 1 on R27 register write operation causes new R27 value and any pending value in R28, R29, or R30 to go into effect. Logic 0 on R27 register write causes new value to be pending an update bit event on R27, R28, R29, or R30. Notch filter control bit 0 = disabled 1 = enabled NFCU1 27 1B Notch filter 1 NFCEN NFCA0[13:7] Default >> Notch filter A0 coefficient most significant bits. See text and table for details. 0 0 0 00 0 0 0 0 1C Notch filter 2 Reserved NFCAO[6:0] Default >> Notch filter A0 coefficient least significant bits. See text and table for details. 0 0 0 00 0 0 0 0 1D Notch filter 3 Reserved NFCA1[13:7] Default >> Notch filter A1 coefficient most significant bits. See text and table for details. 0 0 0 00 0 0 0 0 1E Notch filter 4 Reserved NFCA1[6:0] Default >> 31 1F 0x000 reset value Update bit feature for simultaneous change of all notch filter parameters. Write-only bit. Logic 1 on R30 register write operation causes new R30 value and any pending value in R27, R28, or R29 to go into effect. Logic 0 on R30 register write causes new value to be pending an update bit event on R27, R28, R29, or R30. NFCU4 30 0x000 reset value Update bit feature for simultaneous change of all notch filter parameters. Write-only bit. Logic 1 on R29 register write operation causes new R29 value and any pending value in R27, R28, or R30 to go into effect. Logic 0 on R29 register write causes new value to be pending an update bit event on R27, R28, R29, or R30. NFCU3 29 0x000 reset value Update bit feature for simultaneous change of all notch filter parameters. Write-only bit. Logic 1 on R28 register write operation causes new R28 value and any pending value in R27, R29, or R30 to go into effect. Logic 0 on R28 register write causes new value to be pending an update bit event on R27, R28, R29, or R30. NFCU2 28 0x000 reset value Reserved Notch filter A1 coefficient least significant bits. See text and table for details. 0 0 0 00 0 0 0 0 0x000 reset value Reserved NAU88C22 Datasheet Rev 0.6 Page 81 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Automatic Level Control function control bits 00 = right and left ALCs disabled 01 = only right channel ALC enabled 10 = only left channel ALC enabled 11 = both right and left channel ALCs enabled ALCEN reserved Set maximum gain limit for PGA volume setting changes under ALC control 111 = +35.25dB (default) 110 = +29.25dB 101 = +23.25dB 100 = +17.25dB 011 = +11.25dB 010 = +5.25dB 001 = -0.75dB 000 = -6.75dB Set minimum gain value limit for PGA volume setting changes under ALC control 000 = -12dB (default) 001 = -6.0dB 010 = 0.0dB 011 = +6.0dB 100 = +12dB 101 = +18dB 110 = +24dB 111 = +30dB ALCMXGAIN 32 20 ALC control 1 ALCMNGAIN Default >> 0 0 0 11 1 0 0 0 0x038 reset value Reserved Hold time before ALC automated gain increase 0000 = 0.00ms (default) 0001 = 2.00ms 0010 = 4.00ms - time value doubles with each bit value increment – 1001 = 512ms 1010 through 1111 = 1000ms ALC target level at ADC output 1111 = -1.5dB below full scale (FS) 1110 = -1.5dB FS (same value as 1111) 1101 = -3.0dB FS 1100 = -4.5dB FS 1011 = -6.0dB FS (default) - target level varies 1.5dB per binary step throughout control range – 0001 = -21.0dB FS 0000 = -22.5dB FS (lowest possible target signal level) ALCHT 33 21 ALC control 2 ALCSL Default >> 0 0 0 00 1 0 NAU88C22 Datasheet Rev 0.6 1 1 0x00B reset value Page 82 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 ALC mode control setting 0 = normal ALC operation 1 = Limiter Mode operation ALC decay time duration per step of gain change for gain increase of 0.75dB of PGA gain. Total response time can be estimated by the total number of steps necessary to compensate for a given magnitude change in the signal. For example, a 6dB decrease in the signal would require eight ALC steps to compensate. Step size for each mode is given by: Normal Mode Limiter Mode 0000 = 500us 0000 = 125us 0001 = 1.0ms 0001 = 250us 0010 = 2.0ms (default) 0010 = 500us (default) ------- time value doubles with each binary bit value -------1000 = 128ms 1000 = 32ms 1001 = 256ms 1001 = 64ms 1010 through 1111 = 512ms 1010 through 1111 = 128ms ALC attack time duration per step of gain change for gain decrease of 0.75dB of PGA gain. Total response time can be estimated by the total number of steps necessary to compensate for a given magnitude change in the signal. For example, a 6dB increase in the signal would require eight ALC steps to compensate. Step size for each mode is given by: Normal Mode Limiter Mode 0000 = 125us 0000 = 31us 0001 = 250us 0001 = 62us 0010 = 500us (default) 0010 = 124us (default) ------- time value doubles with each binary bit value -------1000 = 26.5ms 1000 = 7.95ms 1001 = 53.0ms 1001 = 15.9ms 1010 through 1111 = 128ms 1010 through 1111 = 31.7ms ALCM ALCDCY 34 22 ALC control 3 ALCATK Default >> 0 0 0 11 0 0 1 0 Reserved Reserved ALC noise gate function control bit 0 = disabled 1 = enabled ALC noise gate threshold level 000 = -39dB (default) 001 = -45dB 010 = -51dB 011 = -57dB 100 = -63dB 101 = -69dB 110 = -75dB 111 = -81dB ALCNEN 35 23 Noise gate ALCNTH Default >> 0x032 reset value 0 0 0 01 0 0 0 0 0x010 reset value Reserved Control bit for divide by 2 pre-scale of MCLK path to PLL clock input 0 = MCLK divide by 1 (default) 1 = MCLK divide by 2 Integer portion of PLL input/output frequency ratio divider. Decimal value should be constrained to 6, 7, 8, 9, 10, 11, or 12. Default decimal value is 8. See text for details. PLLMCLK 36 24 PLL N PLLN Default >> 0 0 0 00 1 0 0 0 0x008 reset value Reserved 37 25 PLL K 1 High order bits of fractional portion of PLL input/output frequency ratio divider. See text for details. PLLK[23:18] Default >> 0 0 0 00 1 1 0 0 PLLK[17:9] 38 26 PLL K 2 Default >> 0 1 0 01 0 0 1 1 27 PLL K 3 Default >> 40 28 0x093 reset value Low order bits of fractional portion of PLL input/output frequency ratio divider. See text for details. PLLK{8:0] 39 0x00C reset value Middle order bits of fractional portion of PLL input/output frequency ratio divider. See text for details. 0 1 1 10 1 0 Reserved NAU88C22 Datasheet Rev 0.6 0 1 0x0E9 reset value Reserved Page 83 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Reserved 41 29 3D control 3DDEPTH Default >> 42 2A 3D Stereo Enhancement effect depth control 0000 = 0.0% effect (disabled, default) 0001 = 6.67% effect 0010 = 13.3% effect - effect depth varies by 6.67% per binary bit value – 1110 = 93.3% effect 1111 = 100% effect (maximum effect) 0 0 0 00 0 0 0 0 0x000 reset value Reserved Reserved Mutes the RMIX speaker signal gain stage output in the right speaker submixer 0 = gain stage output enabled 1 = gain stage output muted Right speaker submixer bypass control 0 = right speaker amplifier directly connected to RMIX speaker signal gain stage 1 = right speaker amplifier connected to submixer output (inverts RMIX for BTL) RAUXIN to Right Speaker Submixer input gain control 000 = -15dB (default) 001 = -12dB 010 = -9.0dB 011 = -6.0dB 100 = -3.0dB 101 = 0.0dB 110 = +3.0dB 111 = +6.0dB RAUXIN to Right Speaker Submixer mute control 0 = RAUXIN path to submixer is muted 1 = RAUXIN path to submixer is enabled RMIXMUT RSUBBYP 43 2B Right Speaker Submixer RAUXRSUBG RAUXSMUT Default >> 0 0 0 00 0 0 0 0 MICBIASV RLINRPGA RMICNRPGA 44 2C Input control 0x000 reset value Microphone bias voltage selection control. Values change slightly with R58 MICBIAS mode selection control. Open circuit voltage on MICBIAS pin#32 is shown as follows as a fraction of the VDDA pin#31 supply voltage. Normal Mode Low Noise Mode 00 = 0.9x 00 = 0.85x 01 = 0.65x 01 = 0.60x 10 = 0.75x 10 = 0.70x 11 = 0.50x 11 = 0.50x RLIN right line input path control to right PGA positive input 0 = RLIN not connected to PGA positive input (default) 1 = RLIN connected to PGA positive input RMICN right microphone negative input to right PGA negative input path control 0 = RMICN not connected to PGA negative input (default) 1 = RMICN connected to PGA negative input RMICP right microphone positive input to right PGA positive input enable 0 = RMICP not connected to PGA positive input (default) 1 = RMICP connected to PGA positive input RMICPRPGA Reserved LLIN right line input path control to left PGA positive input 0 = LLIN not connected to PGA positive input (default) 1 = LLIN connected to PGA positive input LMICN left microphone negative input to left PGA negative input path control 0 = LMICN not connected to PGA negative input (default) 1 = LMICN connected to PGA negative input LMICP left microphone positive input to left PGA positive input enable 0 = LMICP not connected to PGA positive input (default) 1 = LMICP connected to PGA positive input LLINLPGA LMICNLPGA LMICPLPGA Default >> 0 0 0 11 0 0 NAU88C22 Datasheet Rev 0.6 1 1 0x033 reset value Page 84 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 PGA volume update bit feature. Write-only bit for synchronized L/R PGA changes If logic = 0 on R45 write, new R45 value stored in temporary register If logic = 1 on R45 write, new R45 and pending R46 values become active Left channel input zero cross detection enable 0 = gain changes to PGA register happen immediately (default) 1 = gain changes to PGA happen pending zero crossing logic Left channel mute PGA mute control 0 = PGA not muted, normal operation (default) 1 = PGA in muted condition not connected to LADC Mix/Boost stage Left channel input PGA volume control setting. Setting becomes active when allowed by zero crossing and/or update bit features. 01 0000 = 0.0dB default setting LPGAU LPGAZC LPGAMT 45 2D Left input PGA gain 00 0000 = -12dB 00 0001 = -11.25dB - volume changes in 0.75dB steps per binary bit value – 11 1110 = +34.50dB 11 1111 = +35.25dB LPGAGAIN Default >> 0 0 0 01 0 0 0 0 RPGAU RPGAZC RPGAMT 46 2E Right input PGA gain 00 0000 = -12dB 00 0001 = -11.25dB - volume changes in 0.75dB steps per binary bit value – 11 1110 = +34.50dB 11 1111 = +35.25dB RPGAGAIN Default >> 0x010 reset value PGA volume update bit feature. Write-only bit for synchronized L/R PGA changes If logic = 0 on R46 write, new R46 value stored in temporary register If logic = 1 on R46 write, new R46 and pending R45 values become active Right channel input zero cross detection enable 0 = gain changes to PGA register happen immediately 1 = gain changes to PGA happen pending zero crossing logic Right channel mute PGA mute control 0 = PGA not muted, normal operation (default) 1 = PGA in muted condition not connected to RADC Mix/Boost stage Right channel input PGA volume control setting. Setting becomes active when allowed by zero crossing and/or update bit features. 01 0000 = 0.0dB default setting 0 0 0 01 0 0 0 0 0x010 reset value Left channel PGA boost control 0 = no gain between PGA output and LPGA Mix/Boost stage input 1 = +20dB gain between PGA output and LPGA Mix/Boost stage input LPGABST Reserved Gain value between LLIN line input and LPGA Mix/Boost stage input 000 = path disconnected (default) 001 = -12dB 010 = -9.0dB 011 = -6.0dB 100 = -3.0dB 101 = 0.0dB 110 = +3.0dB 111 = +6.0dB LPGABSTGAIN 47 2F Left ADC boost Reserved Gain value between LAUXIN auxiliary input and LPGA Mix/Boost stage input 000 = path disconnected (default) 001 = -12dB 010 = -9.0dB 011 = -6.0dB 100 = -3.0dB 101 = 0.0dB 110 = +3.0dB 111 = +6.0dB LAUXBSTGAIN Default >> 1 0 0 00 0 0 NAU88C22 Datasheet Rev 0.6 0 0 0x100 reset value Page 85 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Right channel PGA boost control 0 = no gain between PGA output and RPGA Mix/Boost stage input 1 = +20dB gain between PGA output and RPGA Mix/Boost stage input RPGABST Reserved Gain value between RLIN line input and RPGA Mix/Boost stage input 000 = path disconnected (default) 001 = -12dB 010 = -9.0dB 011 = -6.0dB 100 = -3.0dB 101 = 0.0dB 110 = +3.0dB 111 = +6.0dB RPGABSTGAIN 48 30 Right ADC boost Reserved Reserved Gain value between RAUXIN auxiliary input and RPGA Mix/Boost stage input 000 = path disconnected (default) 001 = -12dB 010 = -9.0dB 011 = -6.0dB 100 = -3.0dB 101 = 0.0dB 110 = +3.0dB 111 = +6.0dB RAUXBSTGAIN Default >> 1 0 0 00 0 0 0 0 0x100 reset value Reserved Left DAC output to RMIX right output mixer cross-coupling path control 0 = path disconnected (default) 1 = path connected Right DAC output to LMIX left output mixer cross-coupling path control 0 = path disconnected (default) 1 = path connected AUXOUT1 gain boost control 0 = preferred setting for 3.6V and lower operation, -1.0x gain (default) 1 = required setting for greater than 3.6V operation, +1.5x gain AUXOUT2 gain boost control 0 = preferred setting for 3.6V and lower operation, -1.0x gain (default) 1 = required setting for greater than 3.6V operation, +1.5x gain LSPKOUT and RSPKOUT speaker amplifier gain boost control 0 = preferred setting for 3.6V and lower operation, -1.0x gain (default) 1 = required setting for greater than 3.6V operation, +1.5x gain Thermal shutdown enable protects chip from thermal destruction on overload 0 = disable thermal shutdown (engineering purposes, only) 1 = enable (default) strongly recommended for normal operation Output resistance control option for tie-off of unused or disabled outputs. Unused outputs tie to internal voltage reference for reduced pops and clicks. 0 = nominal tie-off impedance value of 1kΩ (default) 1 = nominal tie-off impedance value of 30kΩ LDACRMX RDACLMX AUX1BST 49 31 Output control AUX2BST SPKBST TSEN AOUTIMP Default >> 0 0 0 00 0 0 NAU88C22 Datasheet Rev 0.6 1 0 0x002 reset value Page 86 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Gain value between LAUXIN auxiliary input and input to LMAIN left output mixer 000 = -15dB (default) 001 = -12dB 010 = -9.0dB 011 = -6.0dB 100 = -3.0dB 101 = 0.0dB 110 = +3.0dB 111 = +6.0dB LAUXIN input to LMAIN left output mixer path control 0 = LAUXIN not connected to LMAIN left output mixer (default) 1 = LAUXIN connected to LMAIN left output mixer Gain value for bypass from LADC Mix/Boost output to LMAIN left output mixer. 000 = -15dB (default) 001 = -12dB 010 = -9.0dB 011 = -6.0dB 100 = -3.0dB 101 = 0.0dB 110 = +3.0dB 111 = +6.0dB Left bypass path control from LADC Mix/Boost output to LMAIN left output mixer 0 = path not connected 1 = bypass path connected Left DAC output to LMIX left output mixer path control 0 = path disconnected (default) 1 = path connected LAUXMXGAIN LAUXLMX 50 32 Left mixer LBYPMXGAIN LBYPLMX LDACLMX Default >> 0 0 0 00 0 0 0 1 Gain value between LAUXIN auxiliary input and input to LMAIN left output mixer 000 = -15dB (default) 001 = -12dB 010 = -9.0dB 011 = -6.0dB 100 = -3.0dB 101 = 0.0dB 110 = +3.0dB 111 = +6.0dB RAUXIN input to RMAIN right output mixer path control 0 = RAUXIN not connected to RMAIN right output mixer (default) 1 = RAUXIN connected to RMAIN right output mixer Gain value for bypass from LADC Mix/Boost output to LMAIN left output mixer. 000 = -15dB (default) 001 = -12dB 010 = -9.0dB 011 = -6.0dB 100 = -3.0dB 101 = 0.0dB 110 = +3.0dB 111 = +6.0dB Right bypass path control from RADC Mix/Boost output to RMAIN r output mixer 0 = path not connected 1 = bypass path connected Right DAC output to RMIX right output mixer path control 0 = path disconnected (default) 1 = path connected RAUXMXGAIN RAUXRMX 51 33 Right mixer RBYPMXGAIN RBYPRMX RDACRMX Default >> 0x001 reset value 0 0 0 00 0 0 NAU88C22 Datasheet Rev 0.6 0 1 0x001 reset value Page 87 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Headphone output volume update bit feature. Write-only bit for synchronized changes of left and right headphone amplifier output settings If logic = 0 on R52 write, new R52 value stored in temporary register If logic = 1 on R52 write, new R52 and pending R53 values become active Left channel input zero cross detection enable 0 = gain changes to left headphone happen immediately (default) 1 = gain changes to left headphone happen pending zero crossing logic Left headphone output mute control 0 = headphone output not muted, normal operation (default) 1 = headphone in muted condition not connected to LMIX output stage Left channel headphone output volume control setting. Setting becomes active when allowed by zero crossing and/or update bit features. 11 1001 = 0.0dB default setting LHPVU LHPZC LHPMUTE 52 34 LHP volume 00 0000 = -57dB 00 0001 = -56dB - volume changes in 1.0dB steps per binary bit value – 11 1110 = +5.0dB 11 1111 = +6.0dB LHPGAIN Default >> 0 0 0 11 1 0 0 1 Headphone output volume update bit feature. Write-only bit for synchronized changes of left and right headphone amplifier output settings If logic = 0 on R53 write, new R53 value stored in temporary register If logic = 1 on R53 write, new R53 and pending R52 values become active Right channel input zero cross detection enable 0 = gain changes to right headphone happen immediately (default) 1 = gain changes to right headphone happen pending zero crossing logic Right headphone output mute control 0 = headphone output not muted, normal operation (default) 1 = headphone in muted condition not connected to RMIX output stage Right channel headphone output volume control setting. Setting becomes active when allowed by zero crossing and/or update bit features. 11 1001 = 0.0dB default setting RHPVU RHPZC RHPMUTE 53 35 RHP volume 00 0000 = -57dB 00 0001 = -56dB - volume changes in 1.0dB steps per binary bit value – 11 1110 = +5.0dB 11 1111 = +6.0dB RHPGAIN Default >> 0 0 0 11 1 0 0 1 LSPKZC LSPKMUTE 36 LSPKOUT volume 00 0000 = -57dB 00 0001 = -56dB - volume changes in 1.0dB steps per binary bit value – 11 1110 = +5.0dB 11 1111 = +6.0dB LSPKGAIN Default >> 0x039 reset value Loudspeaker output volume update bit feature. Write-only bit for synchronized changes of left and right headphone amplifier output settings If logic = 0 on R54 write, new R54 value stored in temporary register If logic = 1 on R54 write, new R54 and pending R55 values become active Left loudspeaker LSPKOUT output zero cross detection enable 0 = gain changes to left loudspeaker happen immediately (default) 1 = gain changes to left loudspeaker happen pending zero crossing logic Right loudspeaker LSPKOUT output mute control 0 = loudspeaker output not muted, normal operation (default) 1 = loudspeaker in muted condition Left loudspeaker output volume control setting. Setting becomes active when allowed by zero crossing and/or update bit features. 11 1001 = 0.0dB default setting LSPKVU 54 0x039 reset value 0 0 0 11 1 0 NAU88C22 Datasheet Rev 0.6 0 1 0x039 reset value Page 88 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Loudspeaker output volume update bit feature. Write-only bit for synchronized changes of left and right headphone amplifier output settings If logic = 0 on R55 write, new R55 value stored in temporary register If logic = 1 on R55 write, new R55 and pending R54 values become active Right loudspeaker RSPKOUT output zero cross detection enable 0 = gain changes to right loudspeaker happen immediately (default) 1 = gain changes to right loudspeaker happen pending zero crossing logic Right loudspeaker RSPKOUT output mute control 0 = loudspeaker output not muted, normal operation (default) 1 = loudspeaker in muted condition Right loudspeaker output volume control setting. Setting becomes active when allowed by zero crossing and/or update bit features. 11 1001 = 0.0dB default setting RSPKVU RSPKZC RSPKMUTE 55 37 RSPKOUT volume 00 0000 = -57dB 00 0001 = -56dB - volume changes in 1.0dB steps per binary bit value – 11 1110 = +5.0dB 11 1111 = +6.0dB RSPKGAIN Default >> 0 0 0 11 1 0 0 1 0x039 reset value Reserved AUXOUT2 output mute control 0 = output not muted, normal operation (default) 1 = output in muted condition AUXOUT2MT Reserved AUX1 Mixer output to AUX2 MIXER input path control 0 = path not connected 1 = path connected Left LADC Mix/Boost output LINMIX path control to AUX2 MIXER input 0 = path not connected 1 = path connected Left LMAIN MIXER output to AUX2 MIXER input path control 0 = path not connected 1 = path connected Left DAC output to AUX2 MIXER input path control 0 = path not connected 1 = path connected AUX1MIX>2 56 38 AUX2 MIXER LADCAUX2 LMIXAUX2 LDACAUX2 Default >> 0 0 0 00 0 0 0 1 0x001 reset value Reserved AUXOUT1 output mute control 0 = output not muted, normal operation (default) 1 = output in muted condition AUXOUT1 6dB attenuation enable 0 = output signal at normal gain value (default) 1 = output signal attenuated by 6.0dB Left LMAIN MIXER output to AUX1 MIXER input path control 0 = path not connected 1 = path connected Left DAC output to AUX1 MIXER input path control 0 = path not connected 1 = path connected Right RADC Mix/Boost output RINMIX path control to AUX1 MIXER input 0 = path not connected 1 = path connected Right RMIX output to AUX1 MIXER input path control 0 = path not connected 1 = path connected Right DAC output to AUX1 MIXER input path control 0 = path not connected 1 = path connected AUXOUT1MT AUX1HALF LMIXAUX1 57 39 AUX1 MIXER LDACAUX1 RADCAUX1 RMIXAUX1 RDACAUX1 Default >> 0 0 0 00 0 0 NAU88C22 Datasheet Rev 0.6 0 1 0x001 reset value Page 89 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Reduce DAC supply current 50% in low power operating mode 0 = normal supply current operation (default) 1 = 50% reduced supply current mode Reduce ADC Mix/Boost amplifier supply current 50% in low power operating mode 0 = normal supply current operation (default) 1 = 50% reduced supply current mode Reduce ADC supply current 50% in low power operating mode 0 = normal supply current operation (default) 1 = 50% reduced supply current mode Reduce loudspeaker amplifier supply current 50% in low power operating mode 0 = normal supply current operation (default) 1 = 50% reduced supply current mode Microphone bias optional low noise mode configuration control 0 = normal configuration with low-Z micbias output impedance 1 = low noise configuration with 200-ohm micbias output impedance Regulator voltage control power reduction options 00 = normal 1.80Vdc operation (default) 01 = 1.61Vdc operation 10 = 1.40 Vdc operation 11 = 1.218 Vdc operation Master bias current power reduction options 00 = normal operation (default) 01 = 25% reduced bias current from default 10 = 14% reduced bias current from default 11 = 25% reduced bias current from default LPDAC LPIPBST LPADC LPSPKD 58 Power 3A Management 4 MICBIASM REGVOLT IBADJ Default >> 0 0 0 00 0 0 0 0 Left channel PCM time slot start count: LSB portion of total number of bit times to wait from frame sync before clocking audio channel data. LSB portion is combined with MSB from R60 to get total number of bit times to wait. LTSLOT[8:0] 59 3B Left time slot Default >> 0 0 0 00 0 0 0 0 PCMTSEN TRI Tri state ADC out after second half of LSB enable 8-bit word length enable ADCOUT output driver 1 = enabled (default) 0 = disabled (driver in high-z state) ADCOUT passive resistor pull-up or passive pull-down enable 0 = no passive pull-up or pull-down on ADCOUT pin 1 = passive pull-up resistor on ADCOUT pin if PUDPS = 1 1 = passive pull-down resistor on ADCOUT pin if PUDPS = 0 ADCOUT passive resistor pull-up or pull-down selection 0 = passive pull-down resistor applied to ADCOUT pin if PUDPE = 1 1 = passive pull-down resistor applied to ADCOUT pin if PUDPE = 1 PUDEN PUDPE 3C 0x000 reset value Time slot function enable for PCM mode. PCM8BIT 60 0x000 reset value Misc. PUDPS Reserved Right channel PCM time slot start count: MSB portion of total number of bit times to wait from frame sync before clocking audio channel data. MSB is combined with LSB portion from R61 to get total number of bit times to wait. Left channel PCM time slot start count: MSB portion of total number of bit times to wait from frame sync before clocking audio channel data. MSB is combined with LSB portion from R59 to get total number of bit times to wait. RTSLOT[9] LTSLOT[9] Default >> 61 3D Right time slot 63 3E 3F Device Revision Number Device ID# 0 0 0x020 reset value Right channel PCM time slot start count: LSB portion of total number of bit times to wait from frame sync before clocking audio channel data. LSB portion is combined with MSB from R60 to get total number of bit times to wait. RTSLOT[8:0] Default >> 62 0 0 0 10 0 0 0 0 0 00 0 0 0 0 0x000 reset value Reserved REV Default >> Device Revision Number for readback over control interface = read-only value 0 0 x xx x x x x 0x07F for RevA silicon 0 0 0 01 1 0 1 0 0x01A Device ID equivalent to control bus address = read-only value NAU88C22 Datasheet Rev 0.6 Page 90 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 Dither added to DAC modulator to eliminate all non-random noise 0 0000 = dither off 1 0001 = nominal optimal dither 1 1111 = maximum dither Dither added to DAC analog output to eliminate all non-random noise 0000 = dither off 0100 = nominal optimal dither 1111 = maximum dither MOD Dither 65 41 DAC Dither Analog Dither Default >> 1 0 0 01 0 1 0 0 0 0 0 00 0 0 Selects one of two tables used to set the target level for the ALC 0 = default recommended target level table spanning -1.5dB through -22.5dB FS 1 = optional ALC target level table spanning -6.0dB through -28.5dB FS Choose peak or peak-to-peak value for ALC threshold logic 0 = use rectified peak detector output value 1 = use peak-to-peak detector output value Choose peak or peak-to-peak value for Noise Gate threshold logic 0 = use rectified peak detector output value 1 = use peak-to-peak detector output value Real time readout of instantaneous gain value used by left channel PGA 0 0 0x000 reset value 0 0 0 00 0 0 Enable control for ALC fast peak limiter function 0 = enabled (default) 1 = disabled Reserved Real time readout of instantaneous gain value used by right channel PGA 0 0 0x000 reset value 0 0 0 00 1 0 Reserved ADC_Bias Current Override bit 0 = 100% Bias current for 48kHz Sampling 1 = 100% Bias current for 96kHz and 192kHz Reserved Enable 49MHz PLL output 0 = Divide by 4 block enabled 1 = Divide by 2 block enabled Enable DAC_OSR32x 0 = DAC_OSR32x disabled 1 = DAC_OSR32x enabled Enable ADC_OSR32x 0 = ADC_OSR32x disabled 1 = ADC_OSR32x enabled 0 0 0x008 reset value 0 0 0 00 0 0 Set SPI control bus mode regardless of state of Mode pin 0 = normal operation (default) 1 = force SPI 4-wire mode regardless of state of Mode pin Short frame sync detection period value 00 = trigger if frame time less than 255 MCLK edges 01 = trigger if frame time less than 253 MCLK edges 10 = trigger if frame time less than 254 MCLK edges 11 = trigger if frame time less than 255 MCLK edges Enable DSP state flush on short frame sync event 0 = ignore short frame sync events (default) 1 = set DSP state to initial conditions on short frame sync event Enable control for short frame cycle detection logic 0 = short frame cycle detection logic enabled 1 = short frame cycle detection logic disabled Enable control to delay use of notch filter output when filter is enabled 0 = delay using notch filter output 512 sample times after notch enabled (default) 1 = use notch filter output immediately after notch filter is enabled Enable control to mute DAC limiter output when softmute is enabled 0 = DAC limiter output may not move to exactly zero during Softmute (default) 1 = DAC limiter output muted to exactly zero during softmute Enable control to use PLL output when PLL is not in phase locked condition 0 = PLL VCO output disabled when PLL is in unlocked condition (default) 1 = PLL VCO output used as-is when PLL is in unlocked condition Set DAC to use 256x oversampling rate (best at lower sample rates) 0 = Use oversampling rate as determined by Register 0x0A[3] (default) 1 = Set DAC to 256x oversampling rate regardless of Register 0x0A[3] 0 0 0x000 reset value ALCTBLSEL 70 ALC 46 Enhancement 1 ALCPKSEL ALCNGSEL ALCGAINL Default >> PKLIMENA 71 ALC 47 Enhancement 2 Reserved ALCGAINR Default >> ADCB_OVER 72 48 192kHz Sampling PLL49MOUT DAC_OSR32x ADC_OSR32x Default>> 4WSPIENA FSERRVAL FSERFLSH 73 49 Misc Controls FSERRENA NOTCHDLY DACINMUTE PLLLOCKBP DACOSR256 Default >> NAU88C22 Datasheet Rev 0.6 0x114 reset value Page 91 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 0 0 0 00 0 0 Enable direct control over input tie-off resistor switching 0 = ignore Register 0x4A bits to control input tie-off resistor switching 1 = use Register 0x4A bits to override automatic tie-off resistor switching If MANUINEN = 1, use this bit to control right aux input tie-off resistor switch 0 = Tie-off resistor switch for RAUXIN input is forced open 1 = Tie-off resistor switch for RAUXIN input is forced closed If MANUINEN = 1, use this bit to control right line input tie-off resistor switch 0 = Tie-off resistor switch for RLIN input is forced open 1 = Tie-off resistor switch for RLIN input is forced closed If MANUINEN = 1, use this bit to control right PGA inverting input tie-off switch 0 = Tie-off resistor switch for RMICN input is forced open 1 = Tie-off resistor switch for RMICN input is forced closed If MANUINEN =1, use this bit to control right PGA non-inverting input tie-off switch 0 = Tie-off resistor switch for RMICP input is forced open 1 = Tie-off resistor switch for RMICP input is forced closed If MANUINEN = 1, use this bit to control left aux input tie-off resistor switch 0 = Tie-off resistor switch for LAUXIN input is forced open 1 = Tie-off resistor switch for RAUXIN input is forced closed If MANUINEN = 1, use this bit to control left line input tie-off resistor switch 0 = Tie-off resistor switch for LLIN input is forced open 1 = Tie-off resistor switch for LLIN input is forced closed If MANUINEN = 1, use this bit to control left PGA inverting input tie-off switch 0 = Tie-off resistor switch for LMICN input is forced open 1 = Tie-off resistor switch for LMINN input is forced closed If MANUINEN = 1, use this bit to control left PGA non-inverting input tie-off switch 0 = Tie-off resistor switch for LMICP input is forced open 1 = Tie-off resistor switch for LMICP input is forced closed 0 0 0x000 reset value 0 0 0 00 0 0 Reduce bias current to left and right input MIX/BOOST stage 0 = normal bias current 1 = bias current reduced by 50% for reduced power and bandwidth Reserved Increase bias current to left and right input MIX/BOOST stage 0 = normal bias current 1 = bias current increased by 500 microamps Decrease bias current to left and right input MIX/BOOST stage 0 = normal bias current 1 = bias current reduced by 250 microamps Direct manual control to turn on bypass switch around input tie-off buffer amplifier 0 = normal automatic operation of bypass switch 1 = bypass switch in closed position when input buffer amplifier is disabled Direct manual control to turn on switch to ground at input tie-off buffer amp output 0 = normal automatic operation of switch to ground 1 = switch to ground in in closed position when input buffer amplifier is disabled Direct manual control of switch for Vref 600k-ohm resistor to ground 0 = switch to ground controlled by Register 0x01 setting 1 = switch to ground in the closed positioin Direct manual control for switch for Vref 160k-ohm resistor to ground 0 = switch to ground controlled by Register 0x01 setting 1 = switch to ground in the closed position Direct manual control for switch for Vref 6k-ohm resistor to ground 0 = switch to ground controlled by Register 0x01 setting 1 = switch to ground in the closed position 0 0 0x000 reset value MANINENA MANRAUX MANRLIN MANRMICN 74 4A Input Tie-Off Direct Manual Control MANRMICP MANLAUX MANLLIN MANLMICN MANLMICP Default >> IBTHALFI IBT500UP IBT250DN 75 4B Power Reduction and Output Tie-Off Direct Manual Control MANINBBP MANINPAD MANVREFH MANVREFM MANVREFL Default >> 76 AGC 4C Peak-to-Peak Readout 77 4D 78 4E AGC Peak Detector Readout Automute Control and Status Readout P2PVAL Read-only register which outputs the instantaneous value contained in the peak-topeak amplitude register used by the ALC for signal level dependent logic. Value is highest of left or right input when both inputs are under ALC control. PEAKVAL Read-only register which outputs the instantaneous value contained in the peak detector amplitude register used by the ALC for signal level dependent logic. Value is highest of left or right input when both inputs are under ALC control. AMUTCTRL HVDET NSGATE NAU88C22 Datasheet Rev 0.6 Reserved Select observation point used by DAC output automute feature 0 = automute operates on data at the input to the DAC digital attenuator (default) 1 = automute operates on data at the DACIN input pin Read-only status bit of high voltage detection circuit monitoring VDDSPK voltage 0 = voltage on VDDSPK pin measured at approximately 4.0Vdc or less 1 = voltage on VDDSPK pin measured at approximately 4.0Vdc or greater Read-only status bit of logic controlling the noise gate function 0 = signal is greater than the noise gate threshold and ALC gain can change 1 = signal is less than the noise gate threshold and ALC gain is held constant Page 92 of 101 June, 2016 Register Function Name Dec Hex Bit Description 8 7 6 54 3 2 1 0 0 0 0 00 0 0 Read-only status bit of analog mute function applied to DAC channels 0 = not in the automute condition 1 = in automute condition Read-only status bit of digital mute function of the left channel DAC 0 = digital gain value is greater than zero 1 = digital gain is zero either by direct setting or operation of softmute function Read-only status bit of digital mute function of the left channel DAC 0 = digital gain value is greater than zero 1 = digital gain is zero either by direct setting or operation of softmute function 0 0 0x000 reset value 0 0 0 00 0 0 Enable direct control over output tie-off resistor switching 0 = ignore Register 0x4F bits to control input tie-off resistor/buffer switching 1 = use Register 0x4F bits to override automatic tie-off resistor/buffer switching If MANUOUTEN = 1, use this bit to control bypass switch around 1.5x boosted output tie-off buffer amplifier 0 = normal automatic operation of bypass switch 1 = bypass switch in closed position when output buffer amplifier is disabled If MANUOUTEN = 1, use this bit to control bypass switch around 1.0x non-boosted output tie-off buffer amplifier 0 = normal automatic operation of bypass switch 1 = bypass switch in closed position when output buffer amplifier is disabled If MANUOUTEN = 1, use this bit to control left speaker output tie-off resistor switch 0 = tie-off resistor switch for LSPKOUT speaker output is forced open 1 = tie-off resistor switch for LSPKOUT speaker output is forced closed If MANUOUTEN = 1, use this bit to control left speaker output tie-off resistor switch 0 = tie-off resistor switch for RSPKOUT speaker output is forced open 1 = tie-off resistor switch for RSPKOUT speaker output is forced closed If MANUOUTEN = 1, use this bit to control Auxout1 output tie-off resistor switch 0 = tie-off resistor switch for AUXOUT1 output is forced open 1 = tie-off resistor switch for AUXOUT1 output is forced closed If MANUOUTEN = 1, use this bit to control Auxout2 output tie-off resistor switch 0 = tie-off resistor switch for AUXOUT2 output is forced open 1 = tie-off resistor switch for AUXOUT2 output is forced closed If MANUOUTEN = 1, use this bit to control left headphone output tie-off switch 0 = tie-off resistor switch for LHP output is forced open 1 = tie-off resistor switch for LHP output is forced closed If MANUOUTEN = 1, use this bit to control right headphone output tie-off switch 0 = tie-off resistor switch for RHP output is forced open 1 = tie-off resistor switch for RHP output is forced closed 0 0 0x000 reset value ANAMUTE DIGMUTEL DIGMUTER Default >> MANOUTEN SHRTBUFH SHRTBUFL SHRTLSPK 79 4F Output Tie-Off Direct Manual Controls SHRTRSPK SHRTAUX1 SHRTAUX2 SHRTLHP SHRTRHP Default >> 87 57 SPI1[8:0] Enable SPI 4 wire need to set 0x115 SPI1 Default >> 0 0 0 00 0 0 0 0 SPI2[8:0] 87 6C SPI2 Default >> 0 0 0 00 0 0 0 0 0 0 0 00 0 0 0 0 SPI3[8:0] 115 73 0x000 reset value Enable SPI 4 wire need to set 0x03B 0x000 reset value Enable SPI 4 wire need to set 0x129 SPI3 Default >> NAU88C22 Datasheet Rev 0.6 0x000 reset value Page 93 of 101 June, 2016 15 Appendix D: Register Overview DEC HEX NAME Bit 8 Bit 7 Bit 6 Bit5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 0 00 Software Reset RESET (SOFTWARE) 1 01 Power Management 1 DCBUFEN AUX1MXEN AUX2MXEN PLLEN MICBIASEN ABIASEN IOBUFEN REFIMP 2 02 Power Management 2 RHPEN NHPEN SLEEP RBSTEN LBSTEN RPGAEN LPGAEN RADCEN LADCEN 3 03 Power Management 3 AUXOUT1EN AUXOUT2EN LSPKEN RSPKEN Reserved RMIXEN LMIXEN RDACEN LDACEN General Audio Controls 4 04 Audio Interface BCLKP LRP WLEN AIFMT DACPHS ADCPHS MONO 5 05 Companding 0 0 0 CMB8 DACCM ADCCM ADDAP 6 06 Clock Control 1 CLKM MCLKSEL BCLKSEL 0 CLKIOEN 7 07 Clock Control 2 4WSPIEN 0 0 0 0 SMPLR SCLKEN 8 08 GPIO 0 0 0 GPIO1PLL GPIO1PL GPIO1SEL 9 09 Jack Detect 1 JCKMIDEN JCKDEN JCKDIO 0 0 0 0 10 0A DAC Control 0 0 SOFTMT 0 0 DACOS AUTOMT RDACPL LDACPL 11 0B Left DAC Volume LDACVU LDACGAIN 12 0C Right DAC Volume RDACVU RDACGAIN 13 0D Jack Detect 2 0 JCKDOEN1 JCKDOEN0 14 0E ADC Control HPFEN HPFAM HPF ADCOS 0 RADCPL LADCPL 15 F Left ADC Volume LADCVU LADCGAIN 16 10 Right ADC Volume RADCVU RADCGAIN 17 11 Reserved Equalizer 18 12 EQ1-low cutoff EQM 0 EQ1CF EQ1GC 19 13 EQ2-peak 1 EQ2BW 0 EQ2CF EQ2GC 20 14 EQ3-peak 2 EQ3BW 0 EQ3CF EQ3GC 21 15 EQ4-peak3 EQ4BW 0 EQ4CF EQ4GC 22 16 EQ5-high cutoff 0 0 EQ5CF EQ5GC 23 17 Reserved DAC Limiter 24 18 DAC Limiter 1 DACLIMEN DACLIMDCY DACLIMATK 25 19 DAC Limiter 2 0 0 DACLIMTHL DACLIMBST 26 1A Reserved Notch Filter 27 1B Notch Filter 1 NFCU1 NFCEN NFCA0[13:7] 28 1C Notch Filter 2 NFCU2 0 NFCA0[6:0] 29 1D Notch Filter 3 NFCU3 0 NFCA1[13:7] 30 1E Notch Filter 4 NFCU4 0 NFCA1[6:0] 31 1F Reserved ALC and Noise Gate Control 32 20 ALC Control 1 ALCEN 0 ALCMXGAIN ALCMNGAIN 33 21 ALC Control 2 0 ALCHT ALCSL 34 22 ALC Control 3 ALCM ALCDCY ALCATK 35 23 Noise Gate 0 0 0 0 0 ALCNEN ALCNTH Phase Locked Loop 36 24 PLL N 0 0 0 0 PLLMCLK PLLN 37 25 PLL K 1 0 0 0 PLLK[23:18] 38 26 PLL K 2 PLLK[17:9] 39 27 PLL K 3 PLLK[8:0] 40 28 Reserved Miscellaneous 41 29 3D control 0 0 0 0 0 3DDEPTH 42 2A Reserved Right Speaker 43 2B 0 0 0 RMIXMUT RSUBBYP RAUXRSUBG RAUXSMUT Submix 44 2C Input Control MICBIASV RLINRPGA RMICNRPGA RMICPRPGA 0 LLINLPGA LMICNLPGA LMICPLPGA 45 2D Left Input PGA Gain LPGAU LPGAZC LPGAMT LPGAGAIN Right Input PGA 46 2E RPGAU RPGAZC RPGAMT RPGAGAIN Gain 47 2F Left ADC Boost LPGABST 0 LPGABSTGAIN 0 LAUXBSTGAIN 48 30 Right ADC Boost RPGABST 0 RPGABSTGAIN 0 RAUXBSTGAIN 49 31 Output Control 0 0 LDACRMX RDACLMX AUX1BST AUX2BST SPKBST TSEN AOUTIMP 50 32 Left Mixer LAUXMXGAIN LAUXLMX LBYPMXGAIN LBYPLMX LDACLMX 51 33 Right Mixer RAUXMXGAIN RAUXRMX RBYPMXGAIN RBYPRMX RDACRMX 52 34 LHP Volume LHPVU LHPZC LHPMUTE LHPGAIN 53 35 RHP Volume RHPVU RHPZC RHPMUTE RHPGAIN 54 36 LSPKOUT Volume LSPKVU LSPKZC LSPKMUTE LSPKGAIN 55 37 RSPKOUT Volume RSPKVU RSPKZC RSPKMUTE RSPKGAIN AUXOUT2M 56 38 AUX2 Mixer 0 0 0 0 AUX1MIX>2 LADCAUX2 LMIXAUX2 LDACAUX2 T AUXOUT1M 57 39 AUX1 Mixer 0 0 AUX1HALF LMIXAUX1 LDACAUX1 RADCAUX1 RMIXAUX1 RDACAUX1 T NAU88C22 Datasheet Rev 0.6 Page 94 of 101 June, 2016 Default 000 000 000 050 000 140 000 000 000 000 0FF 0FF 000 100 0FF 0FF 12C 02C 02C 02C 02C 032 000 000 000 000 000 038 00B 032 010 008 00C 093 0E9 000 000 000 033 010 010 100 100 002 001 001 039 039 039 039 001 001 DEC HEX NAME Bit 8 Bit 7 Bit 6 Begin NAU88C22 Proprietary Register Space 58 3A Power Management 4 LPDAC LPIPBST LPADC PCM Time Slot and ADCOUT Impedance Option Control 59 3B Left Time Slot 60 3C Misc PCMTSEN TRI PCM8BIT 61 3D Right Time Slot Silicon Revision and Device ID 62 3E Device Revision # Reserved 63 3F Device ID 70 46 ALC Enhancements ALCTBLSEL ALCPKSEL ALCNGSEL 71 47 ALC Enhancements PKLIMENA Reserved 72 48 192kHz Sampling Reserved 73 49 Misc Controls 4WSPIENA FSERRVAL 74 4A Tie-Off Overrides MANINENA MANRAUX MANRLIN 75 51 Power/Tie-off Ctrl IBTHALFI Reserved IBT500UP 76 4C P2P Detector Read 77 4D Peak Detector Read 78 4E Control and Status Reserved Reserved Reserved 79 4F Output tie-off control MANOUTEN SHRTBUFH SHRTBUFL 87 57 SPI 1 108 6C SPI 2 115 73 SPI 3 NAU88C22 Datasheet Rev 0.6 Bit5 Bit 4 LPSPKD MICBIASM PUDEN LTSLOT[8:0] PUDPE RTSLOT[8:0] Bit 3 Bit 2 REGVOLT PUDPS Reserved Bit 1 Bit 0 IBADJ RTSLOT[9] LTSLOT[9] REV = 0x07F for Rev-A ID ALCGAINL ALCGAINR ADCB_OVER Reserved Reserved PLL49MOUT DAC_OSR32x ADC_OSR32x FSERFLSH FSERRENA Reserved Reserved PLLLOKBP DACOS256 MANRMICN MANRMICP MANLAUX MANLLIN MANLMICN MANLMICP IBT250DN MANINBBP MANINPAD MANVREFH MANVREFM MANVREFL P2PVAL PEAKVAL HVDET NSGATE ANAMUTE DIGMUTEL DIGMUTER FASTDEC SHRTLSPK SHRTRSPK SHRTAUX1 SHRTAUX2 SHRTLHP SHRTRHP SPI1[8:0] SPI2[8:0] SPI3[8:0] Page 95 of 101 June, 2016 Default 000 000 020 000 xxx 01A 000 000 008 000 000 000 000 000 000 000 000 000 000 16 Package Dimensions 32-lead plastic QFN 32L; 5X5mm2, 0.8mm thickness, 0.5mm lead pitch NAU88C22 Datasheet Rev 0.6 Page 96 of 101 June, 2016 32-lead plastic QFN 32L; 4X4mm2, 0.8 mm(Max) thickness, 0.40 mm lead pitch NAU88C22 Datasheet Rev 0.6 Page 97 of 101 June, 2016 NAU88C22 Datasheet Rev 0.6 Page 98 of 101 June, 2016 Nuvoton Products are neither intended nor warranted for usage in systems or equipment, any malfunction or failure of which may cause loss of human life, bodily injury or severe property damage. Such applications are deemed, “Insecure Usage”. 17 Ordering Information Nuvoton Part Number Description NAU88C22 xG Package Material: G = Pb-free Package Package Type: NAU88C22 Datasheet Rev 0.6 Y = 32-Pin QFN Package 5x5mm I 32-Pin QFN Package 4x4mm = Page 99 of 101 June, 2016 Version History VERSION DATE PAGE DESCRIPTION 0.1 June, 2015 n/a Initial Release – Preliminary 0.2 September 9, 2015 n/a Update description and part number 0.3 February 3, 2016 0.4 February 19, 2016 12,20 41 35 1, 5-6 5,7, 37 LSPKOUT change to RSPKOUT PLL percale D changed Analog outputs de-pop data delay description Update electrical parameters 4 Ω loading speakers are not recommended in note 0.5 April 27, 2016 3 Added I2C need external R in pin description 0.6 June 22, 2016 90 91 46,87,89 Update 5x5 mm^2 Epad dimension Update 4x4 mm^2 Epad dimension Update SPI 4-wired inforamation Table 25: Version History NAU88C22 Datasheet Rev 0.6 Page 100 of 101 June, 2016 Important Notice Nuvoton Products are neither intended nor warranted for usage in systems or equipment, any malfunction or failure of which may cause loss of human life, bodily injury or severe property damage. Such applications are deemed, “Insecure Usage”. Insecure usage includes, but is not limited to: equipment for surgical implementation, atomic energy control instruments, airplane or spaceship instruments, the control or operation of dynamic, brake or safety systems designed for vehicular use, traffic signal instruments, all types of safety devices, and other applications intended to support or sustain life. All Insecure Usage shall be made at customer’s risk, and in the event that third parties lay claims to Nuvoton as a result of customer’s Insecure Usage, customer shall indemnify the damages and liabilities thus incurred by Nuvoton. NAU88C22 Datasheet Rev 0.6 Page 101 of 101 June, 2016