LP3921

LP3921 Battery Charger Management and Regulator Unit with Integrated Boomer Audio Amplifier August 26, 2008 LP3921 Battery Charger Management and Regulator Unit with Integrated Boomer® Audio Amplifier General Description The LP3921 is a fully integrated charger and multi-regulator unit with a fully differential Boomer audio power amplifier designed for CDMA cellular phones. The LP3921 has a highspeed serial interface which allows for the integration and control of a Li-Ion battery charger, 7 low-noise low-dropout (LDO) voltage regulators and a Boomer audio amplifier. The Li-Ion charger integrates a power FET, reverse current blocking diode, sense resistor with current monitor output, and requires only a few external components. Charging is thermally regulated to obtain the most efficient charging rate for a given ambient temperature. LDO regulators provide high PSRR and low noise ideally suited for supplying power to both analog and digital loads. The Boomer Audio Amplifier is capable of delivering 1.1 watts of continuous average power to an 8Ω BTL load with less than 1% distortion (THD+N). Boomer Audio Power Amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. The Boomer Audio Amplifier 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 and part count is the primary requirement. The Boomer Audio Amplifier contains advanced pop & click circuitry which eliminates noises during turn-on and turn-off transitions. Features ■ Charger — DC adapter or USB input — Thermally regulated Charge Current — Under Voltage Lockout — 50 to 950 mA Programmable Charge Current 3.0V to 5.5V Input Voltage Range Thermal shutdown I2C-compatible Interface for controlling Charger, LDO outputs and enabling Audio output LDO's 7 Low-Noise LDO’s — 2 x 300 mA — 3 x 150 mA — 2 x 80 mA 2% (typ.) Output Voltage Accuracy on LDO's Audio — Fully Differential Amplification — Ability to drive capacitive loads up to 100 pF — No output coupling capacitors, snubber networks or bootstrap capacitors required Space- Efficient 32-pin 5 x 5 mm LLP package ■ ■ ■ ■ ■ ■ Applications ■ ■ ■ ■ CDMA Phone Handsets Low Power Wireless Handsets Handheld Information Appliances Personal Media Players Boomer® is a registered trademark of National Semiconductor Corporation. © 2008 National Semiconductor Corporation 300698 www.national.com LP3921 System Diagram 30069801 www.national.com 2 LP3921 Functional Block Diagram 30069802 3 www.national.com LP3921 Connection Diagram – Device Pin Diagram 30069803 * Date code is in UZXYTT format where: • • • • U - Wafer Fab Code Z - Assembly Plant XY - 2-Digit Date Code TT - Lot Traceability Ordering Information Order Number LP3921SQE LP3921SQ LP3921SQX SPEC NOPB NOPB NOPB Package Marking L3921SQ L3921SQ L3921SQ Supplied As 250 units, Tape & Reel 1000 units, Tape & Reel 4500 units, Tape & Reel www.national.com 4 LP3921 Device Description The LP3921 Charge Management and Regulator Unit is designed to supply charger and voltage output capabilities for mobile systems, e.g. CDMA handsets. The device provides a Li-Ion charging function and 7 regulated outputs. Communication with the device is via an I2C compatible serial interface that allows function control and status read-back. The battery charge management section provides a programmable CC/CV linear charge capability. Following a normal charge cycle a maintenance mode keeps battery voltage between programmable levels. Power levels are thermally regulated to obtain optimum charge levels over the ambient temperature range. CHARGER FEATURES • Pre-charge, CC, CV and Maintenance modes • USB Charge 100 mA/450 mA • Integrated FET • Integrated Reverse Current Blocking Diode • Integrated Sense Resistor • Thermal regulation • Charge Current Monitor Output • Programmable charge current 50 mA - 950 mA with 50 mA steps • Default CC mode current 100 mA • Pre-charge current fixed 50 mA • Termination voltage 4.1V, 4.2V (default), 4.3V, and 4.4V, accuracy better than +/- 0.35% (typ.) • Restart level 100 mV, 150 mV (default) and 200 mV below Termination voltage • Programmable End of Charge 0.1C (default), 0.15C, 0.2C and 0.25C • Enable Control Input • Safety timer • Input voltage operating range 4.5V - 6.0V REGULATORS Seven low-dropout linear regulators provide programmable voltage outputs with current capabilities of 80 mA, 150 mA and 300 mA as given in the table below. LDO1, LDO2 and LDO3 are powered up by default with LDO1 reaching regulation before LDO2 and LDO3 are started. LDO1, LDO3 and LDO7 can be disabled/enabled via the serial interface. LDO1 and LDO2, if enabled, must be in regulation for the device to power up and remain powered. LDO4, LDO5 and LDO6 have external enable pins and may power up following LDO2 as determined by their respective enable. Under voltage lockout oversees device start up with preset level of 2.85V (typ.). POWER SUPPLY CONFIGURATIONS At PMU start up, LDO1, LDO2 and LDO3 are always started with their default voltages. The start up sequence of the LDO's is given below. Startup Sequence LDO1 -> LDO2 -> LDO3 LDO's with external enable control (LDO4, LDO5, LDO6) start immediately after LDO2 if enabled by logic high at their respective control inputs. LDO7 (and LDO1, LDO3) may be programmed to enable/disable once PS_HOLD has been asserted. DEVICE PROGRAMMABILITY An I2C compatible Serial Interface is used to communicate with the device to program a series of registers and also to read status registers. These internal registers allow control over LDO outputs and their levels. The charger functions may also be programmed to alter termination voltage, end of charge current, charger restart voltage, full rate charge current, and also the charging mode. This device internal logic is powered from LDO2. TABLE 1. LDO Default Voltages LDO 1 2 3 4 5 6 7 Function CORE DIGI ANA TCXO RX TX GP mA 300 300 80 80 150 150 150 Default Voltage (V) 1.8 3.0 3.0 3.0 3.0 3.0 3.0 Startup Default ON ON ON OFF OFF OFF OFF Enable Control SI SI TCXO_EN RX_EN TX_EN SI TABLE 2. LDO Output Voltages Selectable via Serial Interface LDO 1 2 3 4 5 6 7 CORE DIGI ANA TCXO RX TX GP mA 300 300 80 80 150 150 150 + + + + + + + + + + 1.5 + 1.8 + 1.85 + 2.5 + + 2.6 + + 2.7 2.75 2.8 2.85 2.9 2.95 3.0 3.05 3.1 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 3.2 + + 3.3 + + 5 www.national.com LP3921 LP3921 Pin Descriptions Pin# 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 ACOK_N RX_EN DO DI PS_HOLD TCXO_EN HF_PWR VSS PON_N RESET_N DI DI DI G DO DO SCL BATT CHG_IN PWR_ON IMON DI P P DI A Name LDO6 TX_EN LDO5 VIN2 LDO7 OUT+ VDD OUTIN+ INGND BYPASS LDO4 LDO3 LDO2 LDO1 VIN1 GNDA SDA Type A DI A P A AO P AO AI AI G A A A A A P G DI/O Description LDO6 Output (TX) Enable control for LDO6 (TX). HIGH = Enable, LOW = Disable A LDO5 Output (RX) Battery Input for LDO3 - LDO7 LDO7 Output (GP) Differential output + DC power input to audio amplifier Differential output Differential input + Differential input Analog Ground Pin Amplifier bypass cap LDO4 Output (TCXO) LDO3 Output (ANA) LDO2 Output (DIGI) LDO1 Output (CORE) Battery Input for LDO1 and LDO2 Analog Ground pin Serial Interface, Data Input/Output Open Drain output, external pull up resistor is needed. (typ. 1.5k) Serial Interface Clock input. External pull up resistor is needed. (typ. 1.5k) Main battery connection. Used as a power connection for current delivery to the battery. DC power input to charger block from wall or car power adapters. Power up sequence starts when this pin is set HIGH. Internal 500k. pull-down resistor. Charge current monitor output. This pin presents an analog voltage representation of the input charging current. VIMON (mV) = (2.47 x ICHG)(mA). Input for power control from external processor/controller. Enable control for LDO4 (TX). HIGH = Enable, LOW = Disable. Power up sequence starts when this pin is set HIGH. Internal 500k. pull-down resistor. Digital Ground pin Active low signal is PWR_ON inverted. Reset Output. Pin stays LOW during power up sequence. 60 ms after LDO1 (CORE) is stable this pin is asserted HIGH. AC Adapter indicator, LOW when 4.5V- 6.0V present at CHG_IN. Enable control for LDO5 (RX). HIGH = Enable, LOW = Disable. Key: A=Analog; D=Digital; I=Input; DI/O=Digital-Input/Output; G=Ground; O=Output; P=Power www.national.com 6 LP3921 Absolute Maximum Ratings (Notes 1, 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. CHG-IN VBATT =VIN1/2, BATT, VDD, HF_PWR All other Inputs Junction Temperature (TJ-MAX) Storage Temperature Max Continuous Power Dissipation (PD-MAX) (Note 3) ESD (Note 4) BATT, VIN1, VIN2, VDD, HF_PWR, CHG_IN, PWR_ON All other pins −0.3 to +6.5V −0.3 to +6.0V −0.3 to VBATT +0.3V, max 6.0V 150°C −40°C to +150°C Internally Limited Operating Ratings CHG_IN (Note 10) VBATT =VIN1/2, BATT, VDD HF_PWR, PWR_ON ACOK_N, SDA, SCL, RX_EN, TX_EN, TCXO_EN, PS_HOLD, RESET_N All other pins Junction Temperature (TJ) Ambient Temperature (TA) (Note 5) (Notes 1, 2) 4.5 to 6.0V 3.0 to 5.5V 0V to 5.5V 0V to (VLDO2 + 0.3V) 0V to (VBATT + 0.3V) −40°C to +125°C -40 to 85°C (Note 9) Thermal Properties Junction to Ambient Thermal Resistance θJA 4L Jedec Board 8 kV HBM 2 kV HBM 30° C/W General Electrical Characteristics Unless otherwise noted, VIN (=VIN1=VIN2=BATT=VDD) = 3.6V, GND = 0V, CVIN1-2=10 µF, CLDOX=1 µF. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, TA = TJ = −40°C to +125°C. (Note 6) Symbol IQ(STANDBY) Parameter Standby Supply Current Condition VIN = 3.6V, UVLO on, internal logic circuit on, all other circuits off Typ 2 Limit Min Max 5 Units µA POWER MONITOR FUNCTIONS Battery Under-Voltage Lockout VUVLO-R Under Voltage Lock-out Higher Threshold LOGIC AND CONTROL INPUTS VIL Input Low Level PS_HOLD, SDA, SCL, RX_EN, TCXO_EN, TX_EN (Note 7) PWR_ON, HF_PWR (Note 7) VIH Input High Level PS_HOLD, SDA, SCL, RX_EN, TCXO_EN, TX_EN (Note 7) PWR_ON, HF_PWR (Note 7) IIL Logic Input Current All logic inputs except PWR_ON and HF_PWR 0V ≤ VINPUT ≤ VBATT RIN Input Resistance PWR_ON, HF_PWR Pull-Down resistance to GND PON_N, RESET_N, SDA, ACOK_N IOUT = 2 mA PON_N, RESET_N, ACOK_N IOUT = -2 mA (Not applicable to Open Drain Output SDA) 0.75* VLDO2 500 kΩ 0.75* VLDO2 0.75* VBATT -5 +5 0.25* VLDO2 0.25* VBATT V V V VIN Rising (Note 7) 2.85 160 2.7 3.0 V °C THERMAL SHUTDOWN V µA LOGIC AND CONTROL OUTPUTS VOL VOH Output Low Level Output High Level 0.25* VLDO2 V V 7 www.national.com LP3921 LDO1 (CORE) Electrical Characteristics Unless otherwise noted, VIN (=VIN1=VIN2=BATT=VDD) = 3.6V, GND = 0V, CVIN1-2=10 µF, CLDOX=1 µF. Note VINMIN is the greater of 3.0V or VOUT1+ 0.5V. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, TA = TJ = −40°C to +125°C. (Note 6) Symbol VOUT1 Parameter Output Voltage Accuracy Output Voltage IOUT1 VDO1 ΔVOUT1 Output Current Output Current Limit Dropout Voltage Line Regulation Load Regulation en1 PSRR tSTART-UP TTransient Output Noise Voltage Power Supply Rejection Ratio Start-Up Time from Internal Enable Start-Up Transient Overshoot Condition IOUT1 = 1 mA, VOUT1= 3.0V Default VINMIN ≤ VIN ≤ 5.5V VOUT1 = 0V IOUT1 = 300 mA (Note 8) VINMIN ≤ VIN ≤ 5.5V IOUT1 = 1 mA 1 mA ≤ IOUT1 ≤ 300 mA 10 Hz ≤ f ≤ 100 kHz, COUT = 1 µF (Note 7) F = 10 kHz, COUT = 1 µF IOUT1 = 20 mA (Note 7) COUT = 1 µF, IOUT1 = 300 mA (Note 7) COUT = 1 µF, IOUT1 = 300 mA (Note 7) 60 120 mV 60 170 µs 65 dB 10 45 mV µVRMS 600 220 2 310 mV mV 1.8 300 Typ Limit Min −2 −3 Max +2 +3 V mA Units % www.national.com 8 LP3921 LDO2 (DIGI) Electrical Characteristics Unless otherwise noted, VIN (=VIN1=VIN2=BATT=VDD) = 3.6V, GND = 0V, CVIN1-2=10 µF, CLDOX=1 µF. Note VINMIN is the greater of 3.0V or VOUT2+ 0.5V. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, TA = TJ = −40°C to +125°C. (Note 6) Symbol VOUT2 Parameter Output Voltage Accuracy Output Voltage IOUT2 VDO2 ΔVOUT2 Output Current Output Current Limit Dropout Voltage Line Regulation Load Regulation en2 PSRR tSTART-UP tTransient Output Noise Voltage Power Supply Rejection Ratio Start-Up Time from Shutdown Start-Up Transient Overshoot Condition IOUT2 = 1 mA, VOUT2= 3.0V Default VINMIN ≤ VIN ≤ 5.5V VOUT2 = 0V IOUT2 = 300 mA (Note 8) VINMIN ≤ VIN ≤ 5.5V IOUT2 = 1mA 1 mA ≤ IOUT2 ≤ 300 mA 10 Hz ≤ f ≤ 100 kHz, COUT = 1 µF (Note 7) F = 10 kHz, COUT = 1 µF IOUT2 = 20 mA (Note 7) COUT = 1 µF, IOUT2 = 300 mA (Note 7) COUT = 1 µF, IOUT2 = 300 mA (Note 7) 40 5 60 30 µs mV 65 dB 10 45 mV µVRMS 600 220 2 310 mV mV 3 300 Typ Limit Min −2 −3 Max +2 +3 V mA Units % LDO3 (ANA), LDO4 (TCXO) Electrical Characteristics Unless otherwise noted, VIN (=VIN1=VIN2=BATT=VDD) = 3.6V, GND = 0V, CVIN1-2=10 µF, CLDOX=1 µF. TCXO_EN high. Note VINMIN is the greater of 3.0V or VOUT3/4 + 0.5V. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, TA = TJ = −40°C to +125°C. (Note 6) Symbol VOUT3, VOUT4 Parameter Output Voltage Accuracy Output Voltage IOUT3, IOUT4 VDO3, VDO4 ΔVOUT3 , ΔVOUT4 Load Regulation en3,en4 PSRR tSTART-UP tTransient Output Noise Voltage Power Supply Rejection Ratio Output Current Output Current Limit Dropout Voltage Line Regulation Condition IOUT3/4 = 1 mA, VOUT3/4= 3.0V LDO3 default LDO4 default VINMIN ≤ VIN ≤ 5.5V VOUT3/4 = 0V IOUT3/4 = 80 mA (Note 8) VINMIN ≤ VIN ≤ 5.5V IOUT3/4 = 1 mA 1mA ≤ IOUT3/4 ≤ 80 mA 10 Hz ≤ f ≤ 100 kHz, COUT = 1 µF (Note 7) F = 10 kHz, COUT = 1 µF IOUT3/4 = 20 mA (Note 7) 40 5 60 30 µs mV 5 45 65 mV µVRMS dB 160 220 2 310 mV mV 3 3 80 mA Typ Limit Min −2 −3 Max +2 +3 V Units % Start-Up Time from Enable COUT = 1 µF, IOUT3/4 = 80mA (Note 7) Start-Up Transient Overshoot COUT = 1µF, IOUT3/4 = 80 mA (Note 7) 9 www.national.com LP3921 LDO5 (RX), LDO6 (TX), LDO7 (GP) Electrical Characteristics Unless otherwise noted, VIN (=VIN1=VIN2=BATT=VDD) = 3.6V, GND = 0V, CVIN1-2=10 µF, CLDOX=1 µF. RX_EN, TX_EN high. LDO7 Enabled via Serial Interface. Note VINMIN is the greater of 3.0V or VOUT5/6/7 + 0.5V. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, TA = TJ = −40°C to +125°C. (Note 6) Symbol VOUT5, VOUT6, VOUT7 Parameter Output Voltage Default Output Voltage Condition IOUT5/6/7 = 1mA, VOUT5/6/7= 3.0V LDO5 LDO6 LDO7 IOUT5, IOUT6, IOUT7 VDO5, VDO6, VDO7 ΔVOUT5, ΔVOUT6, ΔVOUT7 en5, en6, en7 PSRR tSTART-UP tTransient Load Regulation Output Noise Voltage Power Supply Rejection Ratio Output Current Output Current Limit Dropout Voltage Line Regulation VINMIN ≤ VIN ≤ 5.5V VOUT5/6/7 = 0V IOUT5/6/7 = 150 mA (Note 8) VINMIN ≤ VIN ≤ 5.5V IOUT5/6/7 = 1 mA 1mA ≤ IOUT5/6/7 ≤ 150 mA 10 Hz ≤ f ≤ 100 kHz, COUT = 1 µF (Note 7) F = 10 kHz, COUT = 1 µF IOUT5/6/7 = 20 mA (Note 7) 40 5 60 30 µs mV 10 45 65 mV µVRMS dB 300 200 2 280 mV mV 3 3 3 150 mA Typ Limit Min −2 −3 Max +2 +3 V Units % Start-Up Time from Enable COUT = 1 µF, IOUT5/6/7 = 150 mA (Note 7) Start-Up Transient Overshoot COUT = 1 µF, IOUT5/6/7 = 150 mA (Note 3) www.national.com 10 LP3921 Charger Electrical Characteristics Unless otherwise noted, VCHG-IN = 5V, VIN (=VIN1=VIN2=BATT=VDD) = 3.6V.CCHG_IN = 10 µF. Charger set to default settings unless otherwise noted. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, TA = TJ = −25°C to +85°C. (Notes 6, 9) Symbol VCHG-IN VOK_CHG VTERM Parameter Input Voltage Range Operating Range CHG_IN OK trip-point Battery Charge Termination voltage VTERM voltage tolerance ICHG Fast Charge Current Accuracy VCHG_IN - VBATT (Rising) VCHG_IN - VBATT (Falling) Default TJ = 0°C to 85°C ICHG = 450 mA 200 50 4.2 -1 -10 50 +1 +10 950 V % % mA (Note 7) Condition Typ Limit Min 4.5 4.5 Max 6.5 6 Units V mV Programmable full-rate 6.0V ≥ VCHG_IN ≥ 4.5V charge current range (default V BATT < (VCHG_IN - VOK_CHG) 100 mA) VFULL_RATE < VBATT < VTERM (Note 10) Default Charge current programming step IPREQUAL ICHG_USB Pre-qualification current CHG_IN programmable current in USB mode VBATT = 2V 5.5V ≥ VCHG_IN ≥ 4.5V VBATT < (VCHG_IN VOK_CHG) VFULL_RATE < VBATT < VTERM Default = 100 mA VFULL_RATE IEOC VRESTART Full-rate qualification threshold End of Charge Current, % of full-rate current Restart threshold voltage VBATT rising, transition from prequal to full-rate charging 0.1C option selected VBATT falling, transition from EOC to full-rate charge mode. Default options selected - 4.05V ICHG = 100 mA ICHG = 450 mA (Note 7) High Low 100 100 50 50 40 60 mA mA 450 100 3 10 4.05 3.97 4.13 V 0.247 1.112 115 0.947 1.277 2.9 3.1 V % IMON TREG IMON Voltage 1 IMON Voltage 2 Regulated junction temperature Power OK deglitch time Deglitch time Charge timer Deglitch time for end-ofcharge transition V °C Detection and Timing (Note 7) TPOK TPQ_FULL TCHG TEOC VBATT < (VCC - VOK_CHG) Pre-qualification to full-rate charge transition Precharge mode Charging Timeout 32 230 1 5 230 mS mS mS Hrs 11 www.national.com LP3921 Audio Electrical Characteristics Unless otherwise noted, VDD= 3.6V Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, TA= TJ = −25°C to +85°C. (Note 6) Paramater Output Power Total Harmonic Distortion + Noise Power Supply Rejection Ratio Conditions THD = 1% (max); f = 1 kHz, RL = 8Ω PO = 0.25 Wrms; f = 1 kHz Vripple = 200 mVPP f = 217 Hz f = 1 kHz Typical 0.375 0.02 Limit Min Max Units W % Symbol PO THD + N PSRR CMRR VOS 85 85 50 4 73 dB dB mV Common-Mode Rejection Ratio f = 217 Hz, VCM = 200 mVPP Output Offset VacINput = 0V Serial Interface Unless otherwise noted, VIN ( = VIN1 = VIN2 = BATT=VDD) = 3.6V, GND = 0V, CVIN1-2=10 µF, CLDOX=1 µF, and VLDO2 (DIGI) ≥ 1.8V. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, TA= TJ = −40°C to +125°C. (Notes 6, 7) Symbol fCLK tBF tHOLD tCLK-LP tCLK-HP tSU tDATA-HOLD tDATA-SU tSU tTRANS Parameter Clock Frequency Bus-Free Time between START and STOP Hold Time Repeated START Condition CLK Low Period CLK High Period Set-Up Time Repeated START Condition Data Hold Time Data Set-Up Time Set-Up Time for STOP Condition Maximum Pulse Width of Spikes that Must be Suppressed by the Input Filter of both DATA & CLK Signals 50 1.3 0.6 1.3 0.6 0.6 50 100 0.6 Condition Typ Limit Min Max 400 Units kHz µs µs µs µs µs ns ns µs ns www.national.com 12 LP3921 Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics tables. Note 2: All voltages are with respect to the potential at the GND pin. Note 3: Internal Thermal Shutdown circuitry protects the device from permanent damage. Note 4: The human-body model is 100 pF discharged through 1.5 kΩ. The machine model is a 200 pF capacitor discharged directly into each pin, MIL-STD-883 3015.7. Note 5: Care must be exercised where high power dissipation is likely. The maximum ambient temperature may have to be derated. Like the Absolute Maximum power dissipation, the maximum power dissipation for operation depends on the ambient temperature. In applications where high power dissipation and/or poor thermal dissipation exists, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA_MAX) is dependent on the maximum power dissipation of the device in the application (PD_MAX), and the junction to ambient thermal resistance of the device/package in the application (θJA), as given by the following equation: TA_MAX = TJ_MAX-OP – (θJA X PDMAX ). Note 6: All limits are guaranteed. All electrical characteristics having room-temperature limits are tested during production with TJ = 25°C. All hot and cold limits are guaranteed by correlating the electrical characteristics to process and temperature variations and applying statistical process control. Note 7: Guaranteed by design. Note 8: Dropout voltage is the input-to-output voltage difference at which the output voltage is 100 mV below its nominal value. This specification does not apply in cases it implies operation with an input voltage below the 3.0V minimum appearing under Operating Ratings. For example, this specification does not apply for devices having 1.5V outputs because the specification would imply operation with an input voltage at or about 1.5V. Note 9: Junction-to-ambient thermal resistance (θJA) is taken from thermal modelling result, performed under the conditions and guidelines set forth in the JEDEC standard JESD51-7. The value of (θJA) of this product could fall within a wide range, depending on PWB material, layout, and environmental conditions. In applications where high maximum power dissipation exists (high VIN, high IOUT), special care must be paid to thermal dissipation issues in board design. Note 10: Full-charge current is guaranteed for CHG_IN = 4.5 to 6.0V. At higher input voltages, increased power dissipation may cause the thermal regulation to limit the current to a safe level, resulting in longer charging time. 13 www.national.com LP3921 Technical Description DEVICE POWER UP AND SHUTDOWN TIMING 30069837 FIGURE 1. Device Power Up Logic Timing: PWR_ON www.national.com 14 LP3921 30069807 FIGURE 2. Device Power Up Logic Timing: CHG_IN, HF_PWR START UP Device start is initiated by any of the 3 input signals, PWR_ON, HF_PWR and CHG_IN. PWR_ON When PWR_ON goes high the device will remain powered up, a PS_HOLD applied will allow the device to remain powered after the PWR_ON signal has gone low. HF_PWR, CHGIN PS_HOLD needs to be asserted within 1200 ms after a CHG_IN or HF_PWR rising edge has been detected. For applications where a level sensitive input is required the LP3921 is available with a level detect input at HF_PWR. 15 www.national.com LP3921 30069808 FIGURE 3. LP3921 Power On Behavior (Failed PS_Hold) 30069833 FIGURE 4. LP3921 Normal Shutdown Behavior www.national.com 16 LP3921 LP3921 Serial Port Communication Slave Address Code 7h’7E TABLE 3. Control Registers Addr 8h'00 8h'01 8h'02 8h'03 8h'04 8h'05 8h'06 8h'07 8h'0C 8h'10 8h'11 8h'12 Register (default value) OP_EN (0000 0101) LDO1PGM O/P (0000 0001) LDO2PGM O/P (0000 1011) LDO3PGM O/P (0000 1011) LDO4PGM O/P (0000 1011) LDO5PGM O/P (0000 1011) LDO6PGM O/P (0000 1011) LDO7PGM O/P (0000 1011) STATUS (0000 0000) CHGCNTL1 (0000 1001) CHGCNTL2 (0000 0001) CHGCNTL3 (0001 0010) D7 X X X X X X X X PWR_ON_ TRIB D6 X X X X X X X X HF_PWR_ TRIG D5 X X X X X X X X CHG_IN_ TRIG D4 X X X X X X X X X TOUT_ doubling Prog_ ICHG[4] VTERM[0] Tout_ Fullrate X X X D3 LDO7_EN V1_OP[3] V2_OP[3] V3_OP[3] V4_OP[3] V5_OP[3] V6_OP[3] V7_OP[3] X EN_Tout Prog_ ICHG[3] Prog_ EOC[1] Tout_ Prechg X X X D2 LDO3_EN V1_OP[2] V2_OP[2] V3_OP[2] V4_OP[2] V5_OP[2] V6_OP[2] V7_OP[2] X En_EOC Prog_ ICHG[2] Prog_ EOC[0] LDO Mode X X X D1 X V1_OP[1] V2_OP[1] V3_OP[1] V4_OP[1] V5_OP[1] V6_OP[1] V7_OP[1] X X Prog_ ICHG[1] Prog_ VRSTRT[1] Fullrate Tout_ ConstV X APU_TSD_EN D0 LDO1_EN V1_OP[0] V2_OP[0] V3_OP[0] V4_OP[0] V5_OP[0] V6_OP[0] V7_OP[0] X EN_CHG Prog_ ICHG[0] Prog_ VRSTRT[0] PRECHG Bad_Batt amp_en PS_HOLD _DELAY USBMODE CHGMODE Force EOC _EN _EN X X Batt_Over_ Out X X X X X CHGIN_ OK_Out X X X X VTERM[1] EOC X X X 8h'13 CHGSTATUS1 8h'14 CHGSTATUS2 8h'19 Audio_Amp 8h'1C MISC Control1 X Bold Not Used Bits are Read Only type. Codes other than those shown in the table are disallowed. 17 www.national.com LP3921 The following table summarizes the supported output voltages for the LP3921. Default voltages after startup are highlighted in bold. TABLE 4. LDO Output Voltage Programming Data Code LDOx PGM O/P 8h'00 8h'01 8h'02 8h'03 8h'04 8h'05 8h'06 8h'07 8h'08 8h'09 8h'0A 8h'0B 8h'0C 8h'0D 8h'0E 8h'0F LDO1 (V) 1.5 1.8 1.85 2.5 2.6 2.7 2.75 2.8 2.85 2.9 2.95 3.0 3.05 3.1 3.2 3.3 2.5 2.6 2.7 2.75 2.8 2.85 2.9 2.95 3.0 3.05 3.1 3.2 3.3 2.7 2.75 2.8 2.85 2.9 2.95 3.0 3.05 LDO2 (V) VLDO3 (V) LDO4 (V) 1.5 1.8 1.85 2.5 2.6 2.7 2.75 2.8 2.85 2.9 2.95 3.0 3.05 3.1 3.2 3.3 2.7 2.75 2.8 2.85 2.9 2.95 3.0 3.05 2.7 2.75 2.8 2.85 2.9 2.95 3.0 3.05 LDO5 (V) LDO6 (V) LDO7 (V) 1.5 1.8 1.85 2.5 2.6 2.7 2.75 2.8 2.85 2.9 2.95 3.0 3.05 3.1 3.2 3.3 The following table summarizes the supported charging current values for the LP3921. Default charge current after startup is 100 mA. TABLE 5. Charging Current Programming Prog_Ichg[4] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 Prog_Ichg[3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 Prog_Ichg[2] 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 Prog_Ichg[1] 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 Prog_Ichg[0] 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 I_Charge I mA 50 100 (Default) 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 www.national.com 18 LP3921 TABLE 6. Charging Termination Voltage Control VTERM[1] 0 0 1 1 VTERM[0] 0 1 0 1 TABLE 7. End Of Charge Current Control PROG_EOC[1] 0 0 1 1 Note: C is the set charge current. Termination Voltage (V) 4.1 4.2 (Default) 4.3 4.4 PROG_EOC[0] 0 1 0 1 End of Charge Current 0.1 (Default) 0.15C 0.2C 0.25C TABLE 8. Charging Restart Voltage Programming PROG_VRSTRT[1] 0 0 1 1 PROG_VRSTRT[1] 0 1 0 1 Restart Voltage(V) VTERM - 50 mV VTERM - 100 mV VTERM - 150 mV VTERM - 200 mV TABLE 9. USB Charging Selection USB_Mode_En 0 1 0 1 CHG_Mode_En 0 0 1 1 Mode Fast Charge Fast Charge USB USB Current Default or Selection Default or Selection 100 mA 450 mA nation voltage level. For start up the EOC function is disabled. This function should be enabled once start up is complete and a battery has been detected. EOC is enabled via register CHGCNTL1, Table 10. The full rate constant current rate of charge may be programmed to 19 levels from 50 mA to 950 mA. These values are given in Table 5 and Table 13. The charge mode may be programmed to USB mode when the charger input is applied and the battery voltage is above 3.0V. This provides two programmable current levels of 100 mA and 450 mA for a USB sourced supply input at CHG_IN. Table 9. EOC EOC is disabled by default and should be enabled when the system processor is awake and the system detects that a battery is present. PROGRAMMING INFORMATION TABLE 10. Register Address 8h'10: CHGCNTL1 BIT 2 NAME En_EOC FUNCTION Enables the End Of Charge current level threshold detection. When set to '0' the EOC is disabled. Battery Charge Management A charge management system allowing the safe charge and maintenance of a Li-Ion battery is implemented on the LP3921. This has a CC/CV linear charge capability with programmable battery regulation voltage and end of charge current threshold. The charge current in the constant current mode is programmable and a maintenance mode monitors for battery voltage drop to restart charging at a preset level. A USB charging mode is also available with 2 charge current levels. CHARGER FUNCTION Following the correct detection of an input voltage at the charger pin the charger enters a pre-charge mode. In this mode a constant current of 50 mA is available to charge the battery to 3.0V. At this voltage level the charge management applies the default (100 mA) full rate constant current to raise the battery voltage to the termination voltage level (default 4.2V). The full rate charge current may be programmed to a different level at this stage. When termination voltage (VTERM) is reached, the charger is in constant voltage mode and a constant voltage of 4.2V is maintained. This mode is complete when the end of charge current (default 0.1C) is detected and the charge management enters the maintenance mode. In maintenance mode the battery voltage is monitored for the restart level (4.05V at the default settings) and the charge cycle is re-initiated to re-establish the termi- The End Of Charge current threshold default setting is at 0.1C. This EOC value is set relative to C the set full rate con19 www.national.com LP3921 stant current. This threshold can be set to 0.1C, 0.15C, 0.2C or 0.25C by changing the contents of the PROG_EOC[1:0] register bits. TABLE 11. Register Address 8h'12: CHGCNTL3 BIT 2 3 NAME Prog_EOC[0] Prog_EOC[1] FUNCTION Set the End Of Charge Current. See Table 7. CHARGER FULL RATE CURRENT Programming Information TABLE 13. Register Address 8h'11: CHGCNTL2 Data BITs 000[00000] 000[00001] 000[00010] 000[00011] 000[00100] 000[00101] 000[00110] 000[00111] 000[01000] 000[01001] 000[01010] 000[01011] 000[01100] 000[01101] 000[01110] 000[01111] 000[10000] 000[10001] 000[10010] HEX 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 NAME Prog_ICHG FUNCTION 50 mA 100 mA 150 mA 200 mA 250 mA 300 mA 350 mA 400 mA 450 mA 500 mA 550 mA 600 mA 650 mA 700 mA 750 mA 800 mA 850 mA 900 mA 950 mA TERMINATION AND RESTART The termination and restart voltage levels are determined by the data in the VTERM[1:0] and PROG_VSTRT[1:0] bits in the control register. The restart voltage is programmed relative to the selected termination voltage. The Termination voltages available are 4.1V, 4.2V (default), 4.3V, and 4.4V. The Restart voltages are determined relative to the termination voltage level and may be set to 50 mV, 100 mV, 150 mV (default), and 200 mV below the set termination voltage level. TABLE 12. Register Address 8h'12: CHGCNTL3 BIT 4 5 0 1 NAME VTERM[0] VTERM[1] VRSTR[0] VRSTR[1] FUNCTION Set the charging termination voltage. See Table 6. Set the charging restart voltage. See Table 8. www.national.com 20 LP3921 30069836 FIGURE 5. Simplified Charger Functional State Diagram (EOC is enabled) The charger operation may be depicted by the following graphical representation of the voltage and current profiles. 21 www.national.com LP3921 30069835 FIGURE 6. Charge Cycle Diagram www.national.com 22 LP3921 Further Charger Register Information CHARGER CONTROL REGISTER 1 TABLE 14. Register Address 8h'10: CHGCNTL1 BIT 7 6 NAME USB_MODE _EN CHG_MODE _EN FUNCTION (if bit = '1') Sets the Current Level in USB mode. Forces the charger into USB mode when active high. If low, charger is in normal charge mode. Forces an EOC event. Doubles the timeout delays for all timeout signals. Enables the timeout counters. When set to '0' the timeout counters are disabled. Enables the End of Charge current level threshold detection. When set to '0' the functions are disabled. Forces the charger into LDO mode. Charger enable. IMON CHARGE CURRENT MONITOR Charge current is monitored within the charger section and a proportional voltage representation of the charge current is presented at the IMON output pin. The output voltage relationship to the actual charge current is represented in the following graph and by the equation: VIMON(mV) = (2.47 x ICHG)(mA) 5 4 3 FORCE _EOC TOUT_ Doubling EN_Tout 2 EN_EOC 30069811 1 0 Set_ LDOmode EN_CHG FIGURE 7. IMON Voltage vs. Charge Current Note that this function is not available if there is no input at CHG_IN or if the charger is off due to the input at CHG_IN being less than the compliance voltage. TABLE 15. Register Address 8h'13: CHGSTATUS1 BIT 7 6 5 NAME BAT_OVER _OUT CHGIN_ OK_Out EOC FUNCTION (if bit = '1') Is set when battery voltage exceeds 4.7V. Is set when a valid input voltage is detected at CHG_IN pin. Is set when the charging current decreases below the programmed End Of Charge level. Set after timeout on full rate charge. Set after timeout for precharge mode. This bit is disabled in LP3921. Contact NSC sales if this option is required as in LP3918–L. Set when the charger is in CC/CV mode. Set during precharge. LDO Information OPERATIONAL INFORMATION The LP3921 has 7 LDO's of which 3 are enabled by default, LDO's 1,2 and 3 are powered up during the power up sequence. LDO's 4, 5 and 6 are separately, externally enabled and will follow LDO2 in start up if their respective enable pin is pulled high. LDO2, LDO3 and LDO7 can be enabled/disabled via the serial interface. LDO2 must remain in regulation otherwise the device will power down. While LDO1 is enabled this must also be in regulation for the device to remain powered. If LDO1 is disabled via I2C interface the device will not shut down. INPUT VOLTAGES There are two input voltage pins used to power the 7 LDO's on the LP3921. VIN2is the supply for LDO3, LDO4, LDO5, LDO6 and LDO7. VIN1is the supply for LDO1 and LDO2. PROGRAMMING INFORMATION Enable via Serial Interface TABLE 17. Register Address 8h'00: OP_EN BIT 0 2 3 NAME LDO1_EN LDO3_EN LDO7_EN FUNCTION Bit set to '0' - LDO disabled Bit set to '1' - LDO enabled 4 3 2 Tout_ Fullrate Tout_ Precharge LDO_Mode 1 0 Fullrate PRECHG Charger Status Register 2 Read only TABLE 16. Register Address 8h'13: CHGSTATUS2 BIT 1 0 NAME Tout_ConstV BAD_BATT FUNCTION (if bit = '1') Set after timeout in CV phase. Set at bad battery state. Note that the default setting for this Register is [0000 0101]. This shows that LDO1 and LDO3 are enabled by default whereas LDO7 is not enabled by default on start up. 23 www.national.com LP3921 TABLE 18. LDO Output Programming Register Add (hex) 01 02 03 04 05 06 07 Name Data Range Output Voltage (hex) 03 - 0F 00 - 0F 05 - 0C 00 - 0F 05 - 0C 05 - 0C 00 - 0F 1.5V to 3.3V (def. 1.8V) 2.5V to 3.3V (def 3.0V) 2.7V to 3.05V (def 3.0V) 1.5V to 3.3V (def 3.0V) 2.7V to 3.05V (def 3.0V) 2.7V to 3.05V (def 3.0V) 1.5V to 3.3V (def 3.0V) It is also recommended that the output capacitor be placed within 1 cm from the output pin and returned to a clean ground line. CAPACITOR CHARACTERISTICS The LDO's on the LP3921 are designed to work with ceramic capacitors on the input and output to take advantage of the benefits they offer. For capacitance values around 1 µF, ceramic capacitors give the circuit designer the best design options in terms of low cost and minimal area. Generally speaking, input and output capacitors require careful understanding of the capacitor specification to ensure stable and correct device operation. Capacitance value can vary with DC bias conditions as well as temperature and frequency of operation. Capacitor values will also show some decrease over time due to aging. The capacitor parameters are also dependant on the particular case size with smaller sizes giving poorer performance figures in general. LDO1PGM O/P LDO2PGM O/P LDO3PGM O/P LDO4PGM O/P LDO5PGM O/P LDO6PGM O/P LDO7PGM O/P See Table 4 for full programmable range of values. EXTERNAL CAPACITORS The Low Drop Out Linear Voltage regulators on the LP3921 require external capacitors to ensure stable outputs. The LDO's on the LP3921 are specifically designed to use small surface mount ceramic capacitors which require minimum board space. These capacitors must be correctly selected for good performance INPUT CAPACITOR Input capacitors are required for correct operation. It is recommended that a 10 µF capacitor be connected between each of the voltage input pins and ground (this capacitance value may be increased without limit). This capacitor must be located a distance of not more than 1 cm from the input pin and returned to a clean analogue ground. A ceramic capacitor is recommended although a good quality tantalum or film capacitor may be used at the input. Warning: Important: Tantalum capacitors can suffer catastrophic failures due to surge current when connected to a low-impedance source of power (like a battery or a very large capacitor). If a tantalum capacitor is used at the input, it must be guaranteed by the manufacturer to have surge current rating sufficient for the application. There are no requirements for the ESR (Equivalent Series Resistance) on the input capacitor, but tolerance and temperature coefficient must be considered when selecting the capacitor to ensure the capacitance will remain within its operational range over the entire operating temperature range and conditions. 30069812 FIGURE 8. DC Bias (V) As an example, Figure 8 shows a typical graph showing a comparison of capacitor case sizes in a Capacitance vs DC Bias plot. As shown in the graph, as a result of DC Bias condition the capacitance value may drop below minimum capacitance value given in the recommended capacitor table (0.7 µF in this case). Note that the graph shows the capacitance out of spec for 0402 case size capacitor at higher bias voltages. It is therefore recommended that the capacitor manufacturers specifications for the nominal value capacitor are consulted for all conditions as some capacitor sizes (e.g., 0402) may not be suitable in the actual application. Ceramic capacitors have the lowest ESR values, thus making them best for eliminating high frequency noise. The ESR of a typical 1 µF ceramic capacitor is in the range of 20 mΩ to 40 mΩ, and also meets the ESR requirements for stability. The temperature performance of ceramic capacitors varies by type. Capacitor type X7R is specified with a tolerance of ±15% over temperature range -55ºC to +125ºC. The X5R has similar tolerance over the reduced temperature range -55ºC to +85ºC. Most large value ceramic capacitors ( The DAP's PCB copper pad is connected to a large plane of continuous unbroken copper. This plane forms a thermal mass and heat sink and radiation area. Place the heat sink area on either outside plane in the case of a two-sided PCB, or on an inner layer of a board with more than two layers. Connect the DAP copper pad to the inner layer or backside copper heat sink area with a thermal via. The via diameter should be 0.012 in. to 0.013 in. Ensure efficient thermal conductivity by platingthrough and solder-filling the vias. Best thermal performance is achieved with the largest practical copper heat sink area. In all circumstances and conditions, the junction temperature must be held below 150°C to prevent activating the LP3921's thermal shutdown protection. Further detailed and specific information concerning PCB layout, fabrication, and mounting an LLP package is available from National Semiconductor's package Engineering Group under application note AN1187. PCB LAYOUT AND SUPPLY REGULATION CONSIDERATIONS FOR DRIVING 4Ω LOADS Power dissipated by a load is a function of the voltage swing across the load and the load's impedance. As load impedance decreases, load dissipation becomes increasingly dependent on the interconnect (PCB trace and wire) resistance between the amplifier output pins and the load's connections. Residual trace resistance causes a voltage drop, which results in power 26 www.national.com LP3921 dissipated in the trace and not in the load as desired. This problem of decreased load dissipation is exacerbated as load impedance decreases. Therefore, to maintain the highest load dissipation and widest output voltage swing, PCB traces that connect the output pins to a load must be as wide as possible. Poor power supply regulation adversely affects maximum output power. A poorly regulated supply's output voltage decreases with increasing load current. Reduced supply voltage causes decreased headroom, output signal clipping, and reduced output power. Even with tightly regulated supplies, trace resistance creates the same effects as poor supply regulation. Therefore, making the power supply traces as wide as possible helps maintain full output voltage swing. POWER DISSIPATION Power dissipation might be a major concern when designing a successful amplifier, whether the amplifier is bridged or single-ended. Equation 2 states the maximum power dissipation point for a single-ended amplifier operating at a given supply voltage and driving a specified output load. PDMAX = (VDD)2 / (2π2RL) Single-Ended possible. A larger half-supply bypass capacitor improves PSRR because it increases half-supply stability. Typical applications employ a 5V regulator with 10 µF and 0.1 µF bypass capacitors that increase supply stability. This, however, does not eliminate the need for bypassing the supply nodes of the LP3921. The LP3921 will operate without the bypass capacitor CB, although the PSRR may decrease. A 1 µF capacitor is recommended for CB. This value maximizes PSRR performance. Lesser values may be used, but PSRR decreases at frequencies below 1 kHz. The issue of CB selection is thus dependant upon desired PSRR and click and pop performance as explained in the section Proper Selection of External Components. SHUTDOWN FUNCTION In order to reduce power consumption while not in use, the audio amplifier can be shut down by setting amp_en to 0 in the Audio_Amp register. On power-up, the audio amplifier is in shut down until enabled. (Contact NSC sales for a different option.) (See Table 22.) Thermal shutdown of the PMU will shut down the audio amplifier. (See Thermal Shutdown for recovery options.) Independent temperature sensing within the audio amplifier may also shut down the audio amplifier alone, without affecting PMU control logic. PROPER SELECTION OF EXTERNAL COMPONENTS Proper selection of external components in applications using integrated power amplifiers is critical when optimizing device and system performance. Although the LP3921 is tolerant to a variety of external component combinations, consideration of component values must be made when maximizing overall system quality. The LP3921 is unity-gain stable, giving the designer maximum system flexibility. The LP3921 should be used in low closed-loop gain configurations to minimize THD+N values and maximize signal to noise ratio. Low gain configurations require large input signals to obtain a given output power. Input signals equal to or greater than 1 Vrms are available from sources such as audio codecs. Please refer to the Audio Power Amplifier Design section for a more complete explanation of proper gain selection. When used in its typical application as a fully differential power amplifier the LP3921 does not require input coupling capacitors for input sources with DC common-mode voltages of less than VDD. Exact allowable input common-mode voltage levels are actually a function of VDD, Ri, and Rf and may be determined by Equation 5: VCMi < (VDD-1.2)*((Rf+(Ri)/(Rf)-VDD*(Ri / 2Rf) -RF / RI = AVD (6) (2) However, a direct consequence of the increased power delivered to the load by a bridge amplifier is an increase in internal power dissipation versus a single-ended amplifier operating at the same conditions. PDMAX = 4 * (VDD)2 / (2π2RL) Bridge Mode (3) Since the LP3921 has bridged outputs, the maximum internal power dissipation is 4 times that of a single-ended amplifier. Even with this substantial increase in power dissipation, the LP3921 does not require additional heat sinking under most operating conditions and output loading. From Equation 3, assuming a 5V power supply and an 8Ω load, the maximum power dissipation contribution from the audio amplifier is 625 mW. To this must be added the power dissipated from the power management blocks. The maximum power dissipation thus obtained (PTOT) must not be greater than the power dissipation results from Equation 4: PTOT = PPDMU + PDMAX = (TJMAX - TA) / θJA (4) PDPMU is mainly the sum of power dissipated in the charger and LDO blocks as shown in Equation 5: PDPMU = ICHG (VCHG_IN − VBATT) + (IOUT1 (VBATT − VOUT1) + (IOUT2 (VBATT − VOUT2) + (IOUT3 (VBATT − VOUT3) + ... (approx.) (7) (5) Special care must be taken to match the values of the feedback resistors (RF1 and RF2) to each other as well as matching the input resistors (Ri1 and Ri2) to each other (see Figure 9) more in front. Because of the balanced nature of differential amplifiers, resistor matching differences can result in net DC currents across the load. This DC current can increase power consumption, internal IC power dissipation, reduce PSRR, and possibly damaging the loudspeaker. Table 23 demonstrates this problem by showing the effects of differing values between the feedback resistors while assuming that the input resistors are perfectly matched. The results below apply to the application circuit shown in Figure 9, and assumes that 27 www.national.com The LP3921's θJA in an SQA32A package is 30°C/W. Depending on the ambient temperature, TA, of the system surroundings, Equation 4 can be used to find the maximum internal power dissipation supported by the IC packaging. POWER SUPPLY BYPASSING As with any power amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection ratio (PSRR). The capacitor location on both the bypass and power supply pins should be as close to the device as LP3921 VDD = 5V, RL = 8Ω, and the system has DC coupled inputs tied to ground. TABLE 23. Feedback Resistor Mis-match Tolerance RF1 20% 10% 5% 1% 0% 0.8R 0.9R RF2 1.2R 1.1R V02 - V01 -0.500V -0.250V ILOAD 62.5 mA 31.25 mA 15.63 mA 3.125 mA 0 supply voltage is (VOPEAK + (VDO TOP + (VDO BOT )), where VDO BOT and VDO TOP are extrapolated from the Dropout Voltage vs Supply Voltage curve in the Typical Performance Characteristics section. (8) Using the Output Power vs. Supply Voltage graph for an 8Ω load, the minimum supply rail just about 5V. Extra supply voltage creates headroom that allows the LP3921 to reproduce peaks in excess of 1W without producing audible distortion. At this time, the designer must make sure that the power supply choice along with the output impedance does not violate the conditions explained in the Power Dissipation section. Once the power dissipation equations have been addressed, the required differential gain can be determined from Equation 9. (9) Rf / Ri = AVD (10) 0.95R 1.05R -0.125V 0.99R 1.01R -0.025V R R 0 Similar results would occur if the input resistors were not carefully matched. Adding input coupling capacitors in between the signal source and the input resistors will eliminate this problem, however, to achieve best performance with minimum component count it is highly recommended that both the feedback and input resistors matched to 1% tolerance or better. AUDIO POWER AMPLIFIER DESIGN Design a 1W/8Ω Audio Amplifier Given: Power Output Load Impedance Input Level Input Impedance Bandwidth 1 Wrms 8Ω 1 Vrms 20 kΩ 100 Hz–20 kHz ± 0.25 dB From Equation 10, the minimum AVD is 2.83. Since the desired input impedance was 20 kΩ, a ratio of 2.83:1 of Rf to Ri results in an allocation of Ri = 20 kΩ for both input resistors and Rf = 60 kΩ for both feedback resistors. The final design step is to address the bandwidth requirement which must be stated as a single -3 dB frequency point. Five times away from a -3 dB point is 0.17 dB down from pass band response which is better than the required ±0.25 dB specified. fH = 20 kHz * 5 = 100 kHz (11) A designer must first determine the minimum supply rail to obtain the specified output power. The supply rail can easily be found by extrapolating from the Output Power vs Supply Voltage graphs in the Typical Performance Characteristics section. A second way to determine the minimum supply rail is to calculate the required VOPEAK using Equation 8 and add the dropout voltages. Using this method, the minimum The high frequency pole is determined by the product of the desired frequency pole, fH , and the differential gain, AVD. With AVD = 2.83 and fH = 100 kHz, the resulting GBWP = 150 kHz which is much smaller than the LP3921 GBWP of 10 MHz. This figure displays that if a designer has a need to design an amplifier with a higher differential gain, the LP3921 can still be used without running into bandwidth limitations. www.national.com 28 LP3921 I2C Compatible Serial Bus Interface INTERFACE BUS OVERVIEW The I2C compatible synchronous serial interface provides access to the programmable functions and registers on the device. This protocol uses a two-wire interface for bi-directional communications between the IC’s connected to the bus. The two interface lines are the Serial Data Line (SDA), and the Serial Clock Line (SCL). These lines should be connected to a positive supply, via a pull-up resistor of 1.5 kΩ, and remain HIGH even when the bus is idle. Every device on the bus is assigned a unique address and acts as either a Master or a Slave depending on whether it generates or receives the serial clock (SCL). DATA TRANSACTIONS One data bit is transferred during each clock pulse. Data is sampled during the high state of the serial clock (SCL). Consequently, throughout the clock’s high period, the data should remain stable. Any changes on the SDA line during the high state of the SCL and in the middle of a transaction, aborts the current transaction. New data should be sent during the low SCL state. This protocol permits a single data line to transfer both command/control information and data using the synchronous serial clock. Condition to terminate the transaction. Every byte written to the SDA bus must be 8 bits long and is transferred with the most significant bit first. After each byte, an Acknowledge signal must follow. The following sections provide further details of this process. START AND STOP The Master device on the bus always generates the Start and Stop Conditions (control codes). After a Start Condition is generated, the bus is considered busy and it retains this status until a certain time after a Stop Condition is generated. A high-to-low transition of the data line (SDA) while the clock (SCL) is high indicates a Start Condition. A low-to-high transition of the SDA line while the SCL is high indicates a Stop Condition. 30069810 FIGURE 11. Start and Stop Conditions In addition to the first Start Condition, a repeated Start Condition can be generated in the middle of a transaction. This allows another device to be accessed, or a register read cycle. ACKNOWLEDGE CYCLE The Acknowledge Cycle consists of two signals: the acknowledge clock pulse the master sends with each byte transferred, and the acknowledge signal sent by the receiving device. The master generates the acknowledge clock pulse on the ninth clock pulse of the byte transfer. The transmitter releases the SDA line (permits it to go high) to allow the receiver to send the acknowledge signal. The receiver must pull down the SDA line during the acknowledge clock pulse and ensure that SDA remains low during the high period of the clock pulse, thus signaling the correct reception of the last data byte and its readiness to receive the next byte. 30069813 FIGURE 10. Bit Transfer Each data transaction is composed of a Start Condition, a number of byte transfers (set by the software) and a Stop 30069828 FIGURE 12. Bus Acknowledge Cycle 29 www.national.com LP3921 “ACKNOWLEDGE AFTER EVERY BYTE” RULE The master generates an acknowledge clock pulse after each byte transfer. The receiver sends an acknowledge signal after every byte received. There is one exception to the “acknowledge after every byte” rule. When the master is the receiver, it must indicate to the transmitter an end of data by not-acknowledging (“negative acknowledge”) the last byte clocked out of the slave. This “negative acknowledge” still includes the acknowledge clock pulse (generated by the master), but the SDA line is not pulled down. ADDRESSING TRANSFER FORMATS Each device on the bus has a unique slave address. The LP3921 operates as a slave device with the address 7h’7E (binary 1111110). Before any data is transmitted, the master transmits the address of the slave being addressed. The slave device should send an acknowledge signal on the SDA line, once it recognizes its address. The slave address is the first seven bits after a Start Condition. The direction of the data transfer (R/W) depends on the bit sent after the slave address — the eighth bit. When the slave address is sent, each device in the system compares this slave address with its own. If there is a match, the device considers itself addressed and sends an acknowledge signal. Depending upon the state of the R/W bit (1:read, 0:write), the device acts as a transmitter or a receiver. CONTROL REGISTER WRITE CYCLE • Master device generates start condition. • Master device sends slave address (7 bits) and the data direction bit (R/W = “0”). • Slave device sends acknowledge signal if the slave address is correct. • Master sends control register address (8 bits). • Slave sends acknowledge signal. • Master sends data byte to be written to the addressed register. • Slave sends acknowledge signal. • If master will send further data bytes the control register address will be incremented by one after acknowledge signal. • Write cycle ends when the master creates stop condition. REGISTER READ AND WRITE DETAIL CONTROL REGISTER READ CYCLE • Master device generates a start condition. • Master device sends slave address (7 bits) and the data direction bit (R/W = “0”). • Slave device sends acknowledge signal if the slave address is correct. • Master sends control register address (8 bits). • Slave sends acknowledge signal. • Master device generates repeated start condition. • Master sends the slave address (7 bits) and the data direction bit (R/W = “1”). • Slave sends acknowledge signal if the slave address is correct. • Slave sends data byte from addressed register. • If the master device sends acknowledge signal, the control register address will be incremented by one. Slave device sends data byte from addressed register. • Read cycle ends when the master does not generate acknowledge signal after data byte and generates stop condition. TABLE 24. I2C Read/Write Sequences Address Mode Data Read [Ack] [Ack] [Ack] [Register Date] … additional reads from subsequent register address possible [Ack] [Ack] [Ack] … additional writes to subsequent register address possible Data Write < > Data from master [ ] Data from slave 30069829 FIGURE 13. Register Write Format www.national.com 30 LP3921 30069830 FIGURE 14. Register Read Format 31 www.national.com LP3921 Physical Dimensions inches (millimeters) unless otherwise noted 32–pin LLP Package NS Package Number MKT-SQA32A www.national.com 32 LP3921 Notes 33 www.national.com LP3921 Battery Charger Management and Regulator Unit with Integrated Boomer Audio Amplifier Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers Audio Clock Conditioners Data Converters Displays Ethernet Interface LVDS Power Management Switching Regulators LDOs LED Lighting PowerWise Serial Digital Interface (SDI) Temperature Sensors Wireless (PLL/VCO) www.national.com/amplifiers www.national.com/audio www.national.com/timing www.national.com/adc www.national.com/displays www.national.com/ethernet www.national.com/interface www.national.com/lvds www.national.com/power www.national.com/switchers www.national.com/ldo www.national.com/led www.national.com/powerwise www.national.com/sdi www.national.com/tempsensors www.national.com/wireless WEBENCH Analog University App Notes Distributors Green Compliance Packaging Design Support www.national.com/webench www.national.com/AU www.national.com/appnotes www.national.com/contacts www.national.com/quality/green www.national.com/packaging www.national.com/quality www.national.com/refdesigns www.national.com/feedback Quality and Reliability Reference Designs Feedback THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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