LM4982

LM4982 Ground-Referenced, Ultra Low Noise, 80mW Stereo Headphone Amplifier with IntelliSense and I2C Volume Control February 2006 LM4982 Ground-Referenced, Ultra Low Noise, 80mW Stereo Headphone Amplifier with IntelliSense and I2C Volume Control General Description The LM4982 is a ground referenced, variable gain audio power amplifier capable of delivering 80mW of continuous average power into a 16Ω single-ended load with less than 1% THD+N from a 3V power supply. The I2C volume control allows +18 to -76 dB gain settings. The LM4982 utilizes advanced charge pump technology to generate the LM4982’s negative supply voltage. This eliminates the need for output-coupling capacitors typically used with single-ended loads. IntelliSense is a new circuit technology that allows the LM4982 to detect whether a mono or stereo headphone plug has been inserted into the output jack. Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. The LM4982 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other low voltage applications where minimal power consumption is a primary requirement. The LM4982 incorporates selectable low-power consumption shutdown and channel select modes. The LM4982 contains advanced pop & click circuitry that eliminates noises which would otherwise occur during turn-on and turn-off transitions. Key Specifications j Improved PSRR at 217Hz j Stereo Output Power at VDD = 3V, 66dB 51mW (typ) 0.1µA (typ) RL = 32Ω, THD+N = 1% j Shutdown current Features Ground referenced outputs I2C Volume and mode controls Available in space-saving micro SMD package Ultra low current shutdown mode Advanced pop & click circuitry eliminates noises during turn-on and turn-off transitions n 1.6 – 4.0V operation n No output coupling capacitors, snubber networks, bootstrap capacitors or gain-setting resistors required n Mono/Stereo headphone detect n n n n n Applications n n n n n n Notebook PCs Desktop PCs Mobile Phones PDAs Portable electronic devices MP3 Players Boomer ® is a registered trademark of National Semiconductor Corporation. © 2006 National Semiconductor Corporation DS201614 www.national.com LM4982 Typical Application 20161466 FIGURE 1. Typical Audio Amplifier Application Circuit www.national.com 2 LM4982 Connection Diagrams micro SMD Package micro SMD Marking 20161459 20161401 Top View Order Number LM4982TL Top View XY - Date Code TT - Lot Traceability GG3 – LM4982 See NS Package Number LM4982TL Pin Descriptions Pin Designator A1 A2 A3 A4 B1 B2 B3 B4 C1 C2 C3 C4 D1 D2 D3 D4 Pin Name SGND HPE PVDD CCP+ OUT_L IN_L I2C_VDD PGND SVSS IN_R SCL CCPOUT_R SVDD SDA CPOUT Pin Function Amplifier ground Headphone sende input Charge pump / digital power supply Charge pump fly capacitor positive side Left channel output Left channel input I2C power supply Charge pump / digital ground Amplifier negative supply Right channel input I2C SCL line Charge pump fly capacitor negative side Right channel output Amplifier positive supply I2C SDA line Charge pump power output 3 www.national.com LM4982 Absolute Maximum Ratings (Note 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage Storage Temperature Input Voltage Power Dissipation (Note 3) ESD Susceptibility (Note 4) ESD Susceptibility (Note 5) 4.5V −65˚C to +150˚C −0.3V to VDD +0.3V Internally Limited 2000V 200V Junction Temperature Thermal Resistance θJA (typ) - (TLA16XXX) 150˚C 105˚C/W (Note X) Operating Ratings Temperature Range TMIN ≤ TA ≤ TMAX Supply Voltage −40˚C ≤ TA ≤ +85˚C 1.6V ≤ VDD ≤ 4.0V Audio Amplifier Electrical Characteristics VDD = 3V Symbol Parameter Conditions (Notes 1, 2) The following specifications apply for VDD = 3V, RL = 16Ω, AV = 0dB, unless otherwise specified. Limits apply for TA = 25˚C. LM4982 Typical (Note 6) VIN = 0V, inputs terminated, both channels enabled 8.1 5.1 2.15 0.1 0.7 –70 +18 22 200 47 51 0.05 0.025 % 40 15 29 1.5 4.5 Limits (Notes 7, 8) 11.5 7.3 Units (Limits) mA (max) mA mA µA (max) mV (max) dB dB kΩ (min) kΩ (max) kΩ mW (min) mW IDD Quiescent Power Supply Current Full Power Mode VIN = 0V, inputs terminated, one channel enabled VIN = 0V, inputs terminated, No headphone inserted ISD VOS AV Shutdown Current Output Offset Voltage Gain Max and Min settings With SD enabled RL = 32Ω [B0:B4] = 00000 [B0:B4] = 11111 gain setting 18dB gain setting –76dB THD+N = 1% (max); f = 1kHz, RL = 16Ω, per channel THD+N = 1% (max); f = 1kHz, RL = 32Ω, per channel PO = 50mW, f = 1kHz RL = 16Ω, single channel PO = 50mW, f = 1kHz RL = 32Ω, single channel VRIPPLE = 200mVP-P, input referred f = 217Hz f = 1kHz f = 20kHz RL = 32Ω, POUT = 20mW, f = 1kHz, BW = 20Hz to 22kHz Charge Pump Wake-Up Time Headphone Sense Debounce Time RL = 16Ω, POUT = 1.6mW, f = 1kHz, A-weighted filter In Shutdown Mode RIN Input Resistance POUT Stereo Output Power THD+N Total Harmonic Distortion + Noise PSRR Power Supply Rejection Ratio Full Power Mode 66 55 40 100 300 200 70 180 56 dB SNR TWU TWU XTALK ZOUT IL Vih Vil Signal-to-Noise-Ratio Wake Up Time From Shutdown Wake Up Time Crosstalk Output Impedance Input Leakage HPS in threshold HPS in threshold dB µs ms dB kΩ nA 0.9 x VDD [min] 0.7 x VDD [max] V V ± 0.1 www.national.com 4 LM4982 Audio Amplifier Electrical Characteristics VDD = 3V Symbol Parameter Conditions (Notes 1, 2) (Continued) The following specifications apply for VDD = 3V, RL = 16Ω, AV = 0dB, unless otherwise specified. Limits apply for TA = 25˚C. LM4982 Typical (Note 6) Limits (Notes 7, 8) 3 9 Units (Limits) Ω (min) Ω (max) RINT Intellisense Threshold Resistance 6 Control Interface Electrical Characteristics (Notes 1, 2) The following specifications apply for 1.6V < VDD < 4.0V, unless otherwise specified. Limits apply for TA = 25˚C. Symbol Parameter Conditions Typical (Note 6) t1 t2 t3 t4 t5 VIH VIL Note 1: All voltages are measured with respect to the GND pin unless otherwise specified. Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device performance. Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature, TA. The maximum allowable power dissipation is PDMAX = (TJMAX - TA) / θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4982, see power derating currents for more information. Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor. Note 5: Machine Model, 220pF - 240pF discharged through all pins. Note 6: Typicals are measured at +25˚C and represent the parametric norm. Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). Note 8: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. LM4982 Limits (Notes 7, 8) 2.5 100 0 100 100 0.7 x I2CVDD 0.3 x I CVDD 2 Units (Limits) µs (min) ns (min) ns (min) ns (min) ns (min) V (min) V (max) SCL period SDA Setup Time SDA Stable Time Start Condition Time Stop Condition Time 5 www.national.com LM4982 Typical Performance Characteristics THD+N vs Frequency VDD = 1.8V, RL = 16Ω, PO = 7mW, Mono THD+N vs Frequency VDD = 1.8V, RL = 16Ω, PO = 2mW, Stereo 20161475 20161474 THD+N vs Frequency VDD = 1.8V, RL = 32Ω, PO = 7mW, Mono THD+N vs Frequency VDD = 1.8V, RL = 32Ω, PO = 2mW, Stereo 20161477 20161476 THD+N vs Frequency VDD = 3V, RL = 16Ω, PO = 50mW, Mono THD+N vs Frequency VDD = 3V, RL = 16Ω, PO = 25mW, Stereo 20161482 20161483 www.national.com 6 LM4982 Typical Performance Characteristics THD+N vs Frequency VDD = 3V, RL = 32Ω, PO = 50mW, Mono (Continued) THD+N vs Frequency VDD = 3V, RL = 32Ω, PO = 25mW, Stereo 20161484 20161485 THD+N vs Frequency VDD = 3.6V, RL = 16Ω, PO = 100mW, Mono THD+N vs Frequency VDD = 3.6V, RL = 16Ω, PO = 60mW, Stereo 20161478 20161479 THD+N vs Frequency VDD = 3.6V, RL = 32Ω, PO = 100mW, Mono, THD+N vs Frequency VDD = 3.6V, RL = 32Ω, PO = 60mW, Stereo 20161480 20161481 7 www.national.com LM4982 Typical Performance Characteristics THD+N vs Output Power VDD = 1.8V, RL = 16Ω, f = 1kHz, Mono (Continued) THD+N vs Output Power VDD = 1.8V, RL = 16Ω, f = 1kHz, Stereo 20161486 20161487 THD+N vs Output Power VDD = 1.8V, RL = 32Ω, f = 1kHz, Mono THD+N vs Output Power VDD = 1.8V, RL = 32Ω, f = 1kHz, Stereo 20161488 20161489 THD+N vs Output Power VDD = 3V, RL = 16Ω, f = 1kHz, Mono THD+N vs Output Power VDD = 3V, RL = 16Ω, f = 1kHz, Stereo 20161494 201614B2 www.national.com 8 LM4982 Typical Performance Characteristics THD+N vs Output Power VDD = 3V, RL = 32Ω, f = 1kHz, Mono (Continued) THD+N vs Output Power VDD = 3V, RL = 32Ω, f = 1kHz, Stereo 20161495 20161496 THD+N vs Output Power VDD = 3.6V, RL = 16Ω, f = 1kHz, Mono THD+N vs Output Power VDD = 3.6V, RL = 16Ω, f = 1kHz, Stereo 20161490 20161491 THD+N vs Output Power VDD = 3.6V, RL = 32Ω, f = 1kHz, Mono THD+N vs Output Power VDD = 3.6V, RL = 32Ω, f = 1kHz, Stereo 20161492 20161493 9 www.national.com LM4982 Typical Performance Characteristics Power Dissipation vs Output Power VDD = 1.8V, RL = 16Ω, f = 1kHz (Continued) Power Dissipation vs Output Power VDD = 1.8V, RL = 32Ω, f = 1kHz 20161497 20161498 Power Dissipation vs Output Power VDD = 3V, RL = 16Ω, f = 1kHz Power Dissipation vs Output Power VDD = 3V, RL = 32Ω, f = 1kHz 201614A4 201614A5 Power Dissipation vs Output Power VDD = 3.6V, RL = 16Ω, f = 1kHz Power Dissipation vs Output Power VDD = 3.6V, RL = 32Ω, f = 1kHz 201614A2 201614A3 www.national.com 10 LM4982 Typical Performance Characteristics Output Power vs Power Supply Voltage RL = 16Ω, f = 1kHz, Mono (Continued) Output Power vs Power Supply Voltage RL = 16Ω, f = 1kHz, Stereo 201614B5 201614B6 Output Power vs Power Supply Voltage RL = 32Ω, f = 1kHz, Mono Output Power vs Power Supply Voltage RL = 32Ω, f = 1kHz, Stereo 201614B7 201614B8 Power Supply Current vs Power Supply Voltage VIN = 0V, Mono Power Supply Current vs Power Supply Voltage VIN = 0V, Stereo 201614A6 201614A7 11 www.national.com LM4982 Typical Performance Characteristics PSRR vs Frequency VDD = 1.8V, Vripple = 200mVp-p (Continued) PSRR vs Frequency VDD = 3V, Vripple = 200mVp-p 201614A8 201614B1 PSRR vs Frequency VDD = 3.6V, Vripple = 200mVp-p Crosstalk VDD = 3V, RL = 16Ω, PO= 50mW 201614B0 201614B3 Crosstalk VDD = 3V, RL = 32Ω, PO= 50mW 201614B4 www.national.com 12 LM4982 Application Information 20161468 FIGURE 2. I2C Bus Format 20161467 FIGURE 3. I2C Timing Diagram TABLE 1. Chip Address D7 Chip Address 1 D6 1 D5 1 D4 0 D3 1 D2 1 D1 0 D0 0 TABLE 2. Control Registers D7 Mode Control Volume Control 0 1 D6 0 0 D5 0 0 D4 0 VD4 D3 CD3 VD3 D2 CD2 VD2 D1 CD1 VD1 D0 CD0 VD0 TABLE 3. Mode Control CD3 CD2 CD1 CD0 * Mono mode mixes (Left + Right) / 2, into Left output 1 0 1 0 1 0 1 0 Intellisense Enabled Intellisense Disabled Mute Enabled Mute Disabled Stereo Mono * Normal Operation Shutdown Enabled I2C VOLUME CONTROL The LM4982 can be configured in 32 different gain steps by forcing I2C volume control bits to a desired gain according to the table below: 13 www.national.com LM4982 Application Information VD4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 VD3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 (Continued) TABLE 4. Volume Control VD2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 VD1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 VD0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Gain (dB) –70 –60 –52 –44 –38 –34 –30 –27 –24 –21 –18 –16 –14 –12 –10 –8 –6 –4 –2 0 2 4 6 8 10 12 13 14 15 16 17 18 www.national.com 14 LM4982 Application Information HP SENSE FUNCTION (Continued) Connecting headphones to the headphone jack disconnects the headphone jack contact pin from OUT_L and allows Rpu to pull the HP Sense pin up to VDD. This enables the device. A microprocessor or a switch can replace the headphone jack contact pin. Shutdown (Bit CD0) Logic High Logic High Logic Low Logic Low HPS pin Logic Low Logic High Logic Low Logic High Operational Mode Standby Mode Full Power Mode Micro-Power Shutdown Micro-Power Shutdown FIGURE 5. MONO/STEREO OPERATION When Intellisense is disabled the value of the CD1 bit of the mode control determines if the LM4982 is in mono or stereo mode. When the LM4982 is in mono mode the left and right input signals are mixed to the left channel amplifier and attenuated by -6dB. The right channel amplifier is put in shutdown to save power. The mixing function allows full reproduction of a stereo input signal in a mono headphone and optimum headroom is kept by attenuating by a factor of two. I2C COMPATIBLE INTERFACE The LM4982 uses a serial bus, which conforms to the I2C protocol, to control the chip’s functions with two wires: clock (SCL) and data (SDA). The clock line is uni-directional. The data line is bi-directional (open-collector). The maximum clock frequency specified by the I2C standard is 400kHz. In this discussion, the master is the controlling microcontroller and the slave is the LM4982. The bus format for the I2C interface is shown in Figure 2. The bus format diagram is broken up into six major sections: The "start" signal is generated by lowering the data signal while the clock signal is high. The start signal will alert all devices attached to the I2C bus to check the incoming address against their own address. The 8-bit chip address is sent next, most significant bit first. The data is latched in on the rising edge of the clock. Each address bit must be stable while the clock level is high. After the last bit of the address bit is sent, the master releases the data line high (through a pull-up resistor). Then the master sends an acknowledge clock pulse. If the LM4982 has received the address correctly, then it holds the data line low during the clock pulse. If the data line is not held low during the acknowledge clock pulse, then the master should abort the rest of the data transfer to the LM4982. The 8 bits of data are sent next, most significant bit first. Each data bit should be valid while the clock level is stable high. After the data byte is sent, the master must check for another acknowledge to see if the LM4982 received the data. If the master has more data bytes to send to the LM4982, then the master can repeat the previous two steps until all data bytes have been sent. The "stop" signal ends the transfer. To signal "stop", the data signal goes high while the clock signal is high. The data line should be held high when not in use. 20161460 201614A1 FIGURE 4. INTELLISENSE National’s Intellisense technology allows the LM4982 to detect whether a mono or stereo headphone has been insterted in to the headphone jack. If a mono headphone is inserted into a device that is designed for a stereo headphone, one of the amplifiers will be shorted to ground. Without Intellisense, this may damage the device or, best case, the device will draw excessive current, shortening battery life. Intellisense works by first waiting for one of the following events: • When the device powers up, if a headphone is already inserted • When a headphone is inserted, if the device is already powered up • After the thermal shutdown circuitry is activated. The occurrence of one of these events triggers the Intellisense circuitry to apply a small voltage on both left and right outputs and sense the resulting current through the load. If the load connected to the amplifier is greater than 9Ω, the amplifier driving it will be in full power mode. If the load is less than 3Ω, the LM4982 will assume a short to ground and shutdown the driving amplifier. Intellisense puts the LM4982 in mono mode when the right channel is shorted. For extra protection both amplifiers will be shutdown when the left channel is shorted to ground. The Intellisense feature can be enabled and disabled through an I2C command. This Intellisense feature is designed for headphones with a nominal impedance of 16Ω or greater, using lower impedance loads may cause this feature to operate incorrectly. 15 www.national.com LM4982 Application Information (Continued) I2C INTERFACE POWER SUPPLY PIN (I2CVDD) The LM4982’s I2C interface is powered up through the I2CVDD pin. The LM4982’s I2C interface operates at a voltage level set by the I2CVDD pin which can be set independent to that of the main power supply pin VDD. This is ideal whenever logic levels for the I2C interface are dictated by a microcontroller or microprocessor that is operating at a lower supply voltage than the main battery of a portable system. POWER SUPPLY BYPASSING As with any power amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. Applications that employ a 5V regulator typically use a 10µF in parallel with a 0.1µF filter capacitors to stabilize the regulator’s output, reduce noise on the supply line, and improve the supply’s transient response. However, their presence does not eliminate the need for a local 1.0µF tantalum bypass capacitance connected between the LM4982’s supply pins and ground. Keep the length of leads and traces that connect capacitors between the LM4982’s power supply pins and ground as short as possible. ELIMINATING THE OUTPUT COUPLING CAPACITOR The LM4982 features a low noise inverting charge pump that generates an internal negative supply voltage. This allows the outputs of the LM4982 to be biased about GND instead of a nominal DC voltage, like traditional headphone amplifiers. Because there is no DC component, the large DC blocking capacitors (typically 220µF) are not necessary. The coupling capacitors are replaced by two, small ceramic charge pump capacitors, saving board space and cost. Eliminating the output coupling capacitors also improves low frequency response. In traditional headphone amplifiers, the headphone impedance and the output capacitor form a high pass filter that not only blocks the DC component of the output, but also attenuates low frequencies, impacting the bass response. Because the LM4982 does not require the output coupling capacitors, the low frequency response of the device is not degraded by external components. In addition to eliminating the output coupling capacitors, the ground referenced output nearly doubles the available dynamic range of the LM4982 when compared to a traditional headphone amplifier operating from the same supply voltage. OUTPUT TRANSIENT (’CLICK AND POPS’) ELIMINATED The LM4982 contains advanced circuitry that virtually eliminates output transients (’clicks and pops’). This circuitry prevents all traces of transients when the supply voltage is first applied or when the part resumes operation after coming out of shutdown mode. POWER DISSIPATION Power dissipation is a major concern when using any power amplifier and must be thoroughly understood to ensure a successful design. Equation 1 states the maximum power dissipation point for a single-ended amplifier operating at a given supply voltage and driving a specified output load. PDMAX = (2VDD) 2 Since the LM4982 has two operational amplifiers in one package, the maximum internal power dissipation point is twice that of the number which results from Equation 1. Even with large internal power dissipation, the LM4982 does not require heat sinking over a large range of ambient temperatures. The maximum power dissipation point obtained must not be greater than the power dissipation that results from Equation 2: PDMAX = (TJMAX - TA) / (θJA) (2) For the micro SMD package, θJA = 105˚C/W. TJMAX = 150˚C for the LM4982. Depending on the ambient temperature, TA, of the system surroundings, Equation 2 can be used to find the maximum internal power dissipation supported by the IC packaging. If the result of Equation 1 is greater than that of Equation 2, then either the supply voltage must be decreased, the load impedance increased or TA reduced. Power dissipation is a function of output power and thus, if typical operation is not around the maximum power dissipation point, the ambient temperature may be increased accordingly. SELECTING PROPER EXTERNAL COMPONENTS Optimizing the LM4982’s performance requires properly selecting external components. Though the LM4982 operates well when using external components with wide tolerances, best performance is achieved by optimizing component values. Charge Pump Capacitor Selection Use low ESR (equivalent series resistance) ( < 100mΩ) ceramic capacitors with an X7R dielectric for best performance. Low ESR capacitors keep the charge pump output impedance to a minimum, extending the headroom on the negative supply. Higher ESR capacitors result in reduced output power from the audio amplifiers. Charge pump load regulation and output impedance are affected by the value of the flying capacitor (C1). A larger valued C1 (up to 3.3uF) improves load regulation and minimizes charge pump output resistance. Beyond 3.3uF, the switch-on resistance dominates the output impedance for capacitor values above 2.2uF. The output ripple is affected by the value and ESR of the output capacitor (C2). Larger capacitors reduce output ripple on the negative power supply. Lower ESR capacitors minimize the output ripple and reduce the output impedance of the charge pump. The LM4982 charge pump design is optimized for 2.2uF, low ESR, ceramic, flying, and output capacitors. Input Capacitor Value Selection Amplifying the lowest audio frequencies requires high value input coupling capacitors (Ci in Figure 1). A high value capacitor can be expensive and may compromise space efficiency in portable designs. In many cases, however, the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 150Hz. Applications using speakers with this limited frequency response reap little improvement by using high value input and output capacitors. Besides affecting system cost and size, Ci has an effect on the LM4982’s click and pop performance. The magnitude of the pop is directly proportional to the input capacitor’s size. / (2π2RL) (1) www.national.com 16 LM4982 Application Information (Continued) fi-3dB = 1 / 2πRiCi (3) Thus, pops can be minimized by selecting an input capacitor value that is no higher than necessary to meet the desired −3dB frequency. As shown in Figure 1, the internal input resistor, Ri and the input capacitor, Ci, produce a -3dB high pass filter cutoff frequency that is found using Equation (3). Conventional headphone amplifiers require output capacitors; Equation (3) can be used, along with the value of RL, to determine towards the value of output capacitor needed to produce a –3dB high pass filter cutoff frequency. Also, careful consideration must be taken in selecting a certain type of capacitor to be used in the system. Different types of capacitors (tantalum, electrolytic, ceramic) have unique performance characteristics and may affect overall system performance. (See the section entitled Charge Pump Capacitor Selection.) 17 www.national.com LM4982 Demo Board Artwork 201614A0 Top Layer 20161470 Mid Layer 1 www.national.com 18 LM4982 Demo Board Artwork (Continued) 20161471 Mid Layer 2 20161469 Bottom Layer 19 www.national.com LM4982 Revision History Rev 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Date 7/19/05 7/26/05 10/26/05 10/28/05 11/01/05 11/03/05 11/07/05 01/23/06 01/27/06 2/09/06 Description First PDF. Edited 20161401 (markings) and 20161459 (micro SMD pkg drawing) Text edits input. Also replaced 201614 61 with 66. Texts edit. Deleted PSRR (Stndby Mode) in the 3V EC table (per Nisha). Added the boards and few text edits Few text edits. Added the Typ Perf curves, boards, and text edits. Fixed typos, edited 66, 01, and more of the curves. Input few text edits. First WEB released. www.national.com 20 LM4982 Ground-Referenced, Ultra Low Noise, 80mW Stereo Headphone Amplifier with IntelliSense and I2C Volume Control Physical Dimensions inches (millimeters) unless otherwise noted 16-Bump micro SMD Order Number LM4982TL NS Package Number TLA16CZA X1 = 2.543 ± 0.03 X2 = 2.949 ± 0.03 X3 = 0.6 ± 0.075 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at www.national.com. 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