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19-1014; Rev 0; 10/07
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
General Description
The MAX8821 integrates a charge pump for white LEDs, an audio loudspeaker amplifier, and two lownoise LDOs controlled by an I2C control interface. The high-efficiency, adaptive-mode inverting charge pump drives up to six LEDs with constant current for uniform brightness. The LED current is controlled by an I2C interface and adjusts from 0.1mA to 25.6mA per LED into 32 pseudo-logarithmic steps. Independent voltages for each LED maximize efficiency even with large LED forward voltage (VF) mismatch. An internal temperature derating function reduces the current above +40C to protect the LEDs. The high-efficiency mono Class D audio amplifier delivers up to 2W into a 4 speaker from a 5V input supply. The amplifier features proprietary filterless Active Emissions Limiting (AEL) technology. AEL prevents high-frequency emissions resulting from conventional Class D free-wheeling behavior in the presence of an inductive load. The amplifier offers two modulation schemes: a fixed-frequency mode (FFM) and a spreadspectrum mode (SSM) that reduce EMI-radiated emissions due to the modulation frequency. The amplifier also has robust output protection and high power-supply rejection ratio (PSRR). Click-and-pop suppression is active during power-up/down, enable/disable, and for all mode changes. The amplifier's gain is adjustable through an I2C interface, from -3dB to +24dB in 10 3dB steps. Differential inputs improve common-mode noise rejection. The LDOs in the MAX8821 are designed for low-noise operation. Each LDO output voltage can be individually programmed by the I 2 C interface. Both LDO1 and LDO2 have a high 70dB PSRR rating. The MAX8821 includes soft-start, thermal shutdown, open-circuit, and short-circuit protections, and is available in a compact 28-pin, Thin QFN, 4mm x 4mm package (0.8mm max height).
Features
White LED Inverting Charge Pump Independent Adaptive Current Regulators for Each LED 6 Low-Dropout Current Regulators Flexible I2C Dimming Control for Each LED Ramp-Up/Down, Current Control for Each LED Low 70A (typ) Quiescent Current TA Derating Function Protects LEDs Mono 2W Class D Loudspeaker Amplifier 85% Efficiency (RL = 8, POUT = 600mW) Low 0.05% THD+N at 1kHz High 65dB PSRR at 1kHz Fully Differential Inputs -3dB to +24dB Gain Settings in 3dB Steps Integrated Click-and-Pop Suppression Low Quiescent Current Dual Low-Noise LDO 45VRMS Output Noise, 70dB PSRR Flexible I2C-Controlled Output Voltages 200mA and 300mA Output Current Drive
MAX8821
Ordering Information
PART MAX8821ETI+ TEMP RANGE -40C to +85C PINPACKAGE 28 Thin QFN 4mm x 4mm PKG CODE T2844-1
+Denotes a lead-free package.
Typical Operating Circuit
INPUT 2.7 TO 5.5V IN1 NEG PGND1 IN2 PGND2 IN3 AGND REF LED1 LED2 C1P C1N C2P C2N
Applications
Cell Phones and Smartphones PDAs, Digital Cameras, Camcorders MP3 Players, GPS Devices
MAX8821
LED3 LED4 LED5 LED6
INDIVIDUAL 0.1mA TO 25.6mA DIMMING
CMREF LDO1 DUAL LOW NOISE LDO LDO2
LOGIC CONTROL AND I2C INTERFACE
VDD SDA SCL AIN+ AINEP
DIFFERENTIAL AUDIO INPUT
SPK+ SPK-
LOUDSPEAKER/ EARPIECE
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
ABSOLUTE MAXIMUM RATINGS
IN1, IN2, IN3, VDD to AGND..................................-0.3V to +6.0V SCL, SDA to AGND ....................................-0.3V to (VDD + 0.3V) IN1, IN2, IN3 to NEG .............................................-0.3V to +6.0V AGND to C2N ........................................................-0.3V to +6.0V C1P, C2P to AGND ....................................-0.3V to (VIN1 + 0.3V) LED_, C1N, C2N to NEG............................-0.3V to (VIN1 + 0.3V) LDO1, LDO2, REF to AGND ......................-0.3V to (VIN3 + 0.3V) CMREF, AIN+, AIN-, SPK+, SPKto AGND..................................................-0.3V to (VIN2 + 0.3V) IN1, IN2 to IN3.......................................................-0.3V to +0.3V PGND1, PGND2 to AGND.....................................-0.3V to +0.3V SPK+, SPK- Short Circuit to PGND2 or IN2 ...............Continuous Continuous Power Dissipation (TA = +70C) 28-Pin, Thin QFN 4mm x 4mm (derate 28.6mW/C above +70C) ..............................2286mW Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER VIN1, VIN2, VIN3 Operating Voltage VDD Operating Range Undervoltage Lockout (UVLO) Threshold UVLO Hysteresis VDD Shutdown Threshold IN1, IN2, IN3 Shutdown Supply Current (All Outputs Off) VDD = AGND VDD = 3.6V TA = +25C TA = +85C TA = +25C TA = +85C 0.450 VIN3 rising CONDITIONS MIN 2.7 1.5 2.25 2.45 100 0.865 0.1 0.1 2 2 70 170 120 A LED driver disabled, audio amplifier disabled, and LDO1 and LDO2 enabled No-Load Supply Current Charge pump active, 1MHz switching, all LEDs at 25.6mA setting, audio amplifier disabled, LDO1 and LDO2 disabled LED driver disabled, audio amplifier enabled, LDO1 and LDO2 disabled Thermal Shutdown Thermal-Shutdown Hysteresis CHARGE PUMP SYNC = 0 SYNC = 1, SW_MODE = 00 Switching Frequency (fSW) SYNC = 1, SW_MODE = 01 SYNC = 1, SW_MODE = 10 450 575 1000 550 700 625 25 650 825 kHz 250 10 1.350 1 A TYP MAX 5.5 5.5 2.65 UNITS V V V mV V
Charge pump inactive, 2 LEDs at 0.1mA setting, audio amplifier disabled, LDO1 and LDO2 disabled
1.50
4.00 mA
6.6 +160 20
20 C C
2
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
ELECTRICAL CHARACTERISTICS (continued)
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Soft-Start Time Regulation Voltage Open-Loop NEG Output Resistance Output Current NEG Discharge Resistance in Shutdown LED_ CURRENT REGULATORS Current Setting Range ILED_ TA = +25C Current Accuracy 25.6mA setting TA = -40C to derating function start temperature (enabled by I2C) 0.1 -2 -5 -30 5 +40 TA = +40C to +85C Charge pump inactive Charge pump active 25.6mA setting (Note 2) Charge pump inactive Charge pump active 125 -1.67 2.3 5 72 120 150 100 All LEDs disabled B7, B6 or B3, B2, SYNC = 0, Table 11 TA = +25C TA = +85C 00 Off Blink Time 01 10 11 00 On Blink Time B5, B4 or B1, B0, SYNC = 0, Table 11 LED__RU: B7, B6 or B3, B2 LED__RD: B5, B4 or B1, B0 SYNC = 0, Tables 8, 9, 10 (Note 3) 01 10 11 00 01 10 11 0.01 0.1 524 1048 2097 4194 66 131 262 524 262 524 1048 2097 ms ms ms 1 4.6 14 120 360 175 1 25.6 +2 +5 +30 C %/C mV mV mV A % mA (VIN1 - VNEG) (0.5 x VIN1 - VNEG) / INEG VIN1 = 3.2V, LED VFMAX = 3.9V All LEDs disabled 154 10 CONDITIONS MIN TYP 0.1 5 1.75 3.5 MAX UNITS ms V mA k
MAX8821
0.1mA setting, TA = +25C Current-Derating-Function Start Temperature Current-Derating-Function Slope RDS ON Dropout Voltage Current Regulator Switchover Threshold Current Regulator Switchover Hysteresis Leakage Current in Shutdown
Charge pump inactive to active, VLED_ falling
Ramp-Up/Down Time
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3
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
ELECTRICAL CHARACTERISTICS (continued)
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER AUDIO AMPLIFIER Common-Mode Bias Voltage Output Offset Voltage Common-Mode Input Voltage VAIN+ = VAIN- = VIN3 / 2, audio gain = 0dB 0.5 -3 0 3 6 Audio Gain Table 15, B3:B0 9 12 15 18 21 24 Audio Gain Accuracy Audio gain = -3dB Audio gain = 0dB Audio gain = 3dB Audio gain = 6dB Input Resistance Audio gain = 9dB Audio gain = 12dB Audio gain = 15dB Audio gain = 18dB Audio gain = 21dB Audio gain = 24dB Common-Mode Rejection Ratio Power-Supply Rejection Ratio VIN2 = VIN3 = 3.6V f = 1kHz, VIN2 = VIN3 = 3.6V VAIN+ = VAIN- = VIN3 / 2, 100mVP-P at VIN3 THD+N = 1%, f = 1kHz (Note 4) VIN3 = 3.6V VIN3 = 5V f = 217Hz f = 20kHz RL = 8 RL = 4 RL = 8 RL = 4 0.8 0.36 -3 54.4 49.1 43.1 36.8 30.5 24.6 19.3 14.8 11.1 8.2 99.0 89.2 78.4 66.9 55.5 44.7 35.2 26.9 20.2 15.0 46 46 65 50 0.5 0.85 1.1 2.0 0.05 % W +3 143.5 129.3 113.7 97.0 80.5 64.8 51.0 39.0 29.3 22.0 dB dB k % dB 0.95 x 1.05 x V /2 (VIN3 / 2) IN3 (VIN3 / 2) 1 VIN3 1.2V V mV V CONDITIONS MIN TYP MAX UNITS
Output Power
Total Harmonic Distortion Plus Noise
RL = 8, f = 1kHz, POUT = 0.25W, VIN2 = VIN3 = 3.6V
4
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
ELECTRICAL CHARACTERISTICS (continued)
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER RL = 8, f = 1kHz, POUT = 0.25W, VIN2 = VIN3 = 3.6V SW_MODE = 00 Oscillator Frequency (fosc) Differential Input Resistance Output Current Limit Wake-Up Delay After Short Circuit LDO1 Output Voltage VLDO1 Maximum Output Current Output Current Limit Dropout Voltage Line Regulation Load Regulation Power-Supply Rejection VIN3/VLDO1 Output Voltage Noise (RMS) VLDO1 = 0V ILDO1 = 200mA, TA = +25C (Note 5) VIN3 stepped from 3.4V to 5.5V, ILDO1 = 150mA ILDO1 stepped from 1mA to 300mA 10Hz to 10kHz, ILDO1 = 30mA 100Hz to 100kHz, ILDO1 = 30mA 3.6V VIN3 5.5V, 1mA ILDO1 300mA 1.164 300 400 650 150 2.4 25 70 1000 300 1.200 1.236 V mA mA mV mV mV dB SW_MODE = 01 SW_MODE = 10 Shutdown mode only SPK+, SPK- short circuited to PGND2 or to IN2 CONDITIONS Fixed-frequency mode (FFM) Signal-to-Noise Ratio Spread-spectrum mode (SSM) FFM A weighted SSM A weighted 900 1150 MIN TYP 91 89 93 91 1100 1400 1250 50 100 2 110 k A s 1300 1650 kHz dB MAX UNITS
MAX8821
45
VRMS
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5
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
ELECTRICAL CHARACTERISTICS (continued)
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER CONDITIONS 0000 0001 0010 0011 0100 0101 0110 Programmable Output Voltage ILDO1 = 50mA control bits B3:B0; see Table 13 0111 1000 1001 1010 1011 1100 1101 1110 1111 Shutdown Output Impedance LDO2 Output Voltage VLDO2 Maximum Output Current Output Current Limit Dropout Voltage Line Regulation Load Regulation Power-Supply Rejection VIN3/VLDO2 Output Voltage Noise (RMS) VLDO2 = 0V ILDO2 = 133mA, TA = +25C (Note 5) VIN3 stepped from 3.4V to 5.5V, ILDO2 = 100mA ILDO2 stepped from 1mA to 200mA 10Hz to10kHz, ILDO2 = 20mA 100Hz to100kHz, ILDO2 = 20mA 3.6V VIN3 5.5V, 1mA ILDO2 200mA 1.455 200 250 550 100 2.4 25 70 750 200 1.500 1.545 V mA mA mV mV mV dB LDO1 disabled through I2C MIN 1.164 1.261 1.455 1.552 1.746 1.843 1.940 2.231 2.425 2.522 2.619 2.716 2.813 2.910 3.007 3.104 TYP 1.2 1.3 1.5 1.6 1.8 1.9 2.0 2.3 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 1 MAX 1.236 1.339 1.545 1.648 1.854 1.957 2.060 2.369 2.575 2.678 2.781 2.884 2.987 3.090 3.193 3.296 k V UNITS
45
VRMS
6
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
ELECTRICAL CHARACTERISTICS (continued)
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER CONDITIONS 0000 0001 0010 0011 0100 0101 Programmable Output Voltage ILDO2 = 50mA control bits B3:B0; see Table 14 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 Shutdown Output Impedance LDO2 disabled through I2C MIN 1.455 1.552 1.746 1.940 2.134 2.231 2.328 2.425 2.522 2.619 2.716 2.813 2.910 3.007 3.104 3.201 TYP 1.5 1.6 1.8 2.0 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 1 MAX 1.545 1.648 1.854 2.060 2.266 2.369 2.472 2.575 2.678 2.781 2.884 2.987 3.090 3.193 3.296 3.399 k V UNITS
MAX8821
I2C INTERFACE (Figure 8) Logic Input High Voltage Logic Input Low Voltage Logic Input Current SDA Output Low Voltage I2C Clock Frequency Bus-Free Time Between START and STOP Hold Time Repeated START Condition SCL Low Period SCL High Period Setup Time Repeated START Condition tBUF 1.3 VIL = 0V or VIH = VDD ISDA = 3mA TA = +25C TA = +85C -1 0.01 0.1 0.03 0.4 400 0.7 x VDD 0.3 x VDD +1 V V A V kHz s
tHD_STA tLOW tHIGH tSU_STA
0.6 1.3 0.6 0.6
0.1 0.2 0.2 0.1
s s s s
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7
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
ELECTRICAL CHARACTERISTICS (continued)
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER SDA Hold Time SDA Setup Time Setup Time for STOP Condition tHD_DAT tSU_DAT tSU_STO CONDITIONS MIN 0 100 0.6 TYP -0.01 50 0.1 MAX UNITS s ns s
Note 1: Note 2: Note 3: Note 4: Note 5:
Limits are 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed by design. Dropout voltage is defined as the LED_ to GND voltage when the current into LED_ drops 10% from the value at VLED_ = 0.5V. Ramp-up time is from 0mA to full scale; ramp-down time is from full scale to 0mA. Output power is specified by a combination of a functional output current test and characterization analysis. The dropout voltage is defined as VIN_ - VOUT when VOUT is 100mV below the nominal value of VOUT. The specification only applies when VOUT 3.0V.
Typical Operating Characteristics
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = +25C, unless otherwise noted.) LED CHARGE PUMP
EFFICIENCY vs. SUPPLY VOLTAGE (DRIVING SIX LEDS)
MAX8821 toc01
EFFICIENCY vs. SUPPLY VOLTAGE (DRIVING SIX LEDS)
MAX8821 toc02
EFFICIENCY vs. Li+ BATTERY VOLTAGE DRIVING SIX LEDs
MAX8821 toc03
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 2.7 3.0 3.3 LEDs HAVE MATCHED VF 3.6 3.9 1.6mA/LED 16mA/LED 6.4mA/LED 20.8mA/LED
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 LEDs HAVE MISMATCHED VF 20.8mA/LED 1.6mA/LED 16mA/LED 6.4mA/LED
100 90 80 70 60 20.8mA/LED 50 LEDs HAVE HIGH MATCHED VF 20.8mA/LED 40 6.4mA/LED 1.6mA/LED 16mA/LED
4.2
2.7
3.0
3.3
3.6
3.9
4.2
EFFICIENCY PLED/PBATT (%)
4.2 3.9
3.8
3.7
3.6
3.5 3.4 3.0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED)
SUPPLY CURRENT vs. SUPPLY VOLTAGE (DRIVING SIX LEDs)
MAX8821 toc04
SUPPLY CURRENT vs. SUPPLY VOLTAGE (RGB MODULE)
70 60 SUPPLY CURRENT (mA) 50 40 30 20 10 0 ILED = 1.6mA ILED = 6.4mA ILED = 16mA RGB MODULE: LUMEX SML-LX3632SISUGSBC ILED = 20.8mA
MAX8821 toc05
LED CURRENT MATCHING vs. SUPPLY VOLTAGE (16mA/LED)
16.4 16.3 LED CURRENT (mA) 16.2 16.1 16.0 15.9 15.8 15.7 15.6 15.5 CHARGE PUMP IN 1.5x 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
MAX8821 toc06
250 225 200 SUPPLY CURRENT (mA) 175 150 125 100 75 50 25 0 2.7 3.2 3.7 ILED = 6.4mA ILED = 1.6mA ILED = 16mA LEDs HAVE HIGH MISMATCHED VF ILED = 20.8mA
16.5
4.2
2.7
3.2
3.7
4.2
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
8
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
Typical Operating Characteristics (continued)
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = +25C, unless otherwise noted.)
LED CURRENT vs. AMBIENT TEMPERATURE
MAX8821 toc07
MAX8821
1x MODE OPERATING WAVEFORMS (VIN = 4V)
30 25 LED CURRENT (mA) 20 15 10 5 CURRENT DERATING ENABLED 0 -40 -20 0 20 40 60 80
MAX8821 toc08
VIN VNEG
AC-COUPLED 100mV/div 2V/div 0V
IIN
200mA/div 0A 20mA/div
ILED
ALL LEDs ON, ILED = 25.6mA 400ns/div
0A
100
TEMPERATURE (C)
1.5x MODE OPERATING WAVEFORMS (VIN = 3V)
MAX8821 toc09
LED LINE TRANSIENT WITH MODE CHANGE (VIN = 3.8V TO 3.4V TO 3.8V)
MAX8821 toc10
LED LINE TRANSIENT WITH MODE CHANGE (VIN = 4.2V TO 3.8V TO 4.2V)
MAX8821 toc11
VIN VNEG IIN
AC-COUPLED 100mV/div 0V 2V/div
VIN
3.8V 3.4V
VIN
4.2V 3.8V
IIN IIN 200mA/div 0A
200mA/div 0A
200mA/div 0A 20mA/div ALL LEDs ON, ILED = 25.6mA 400ns/div 0A
ILED
ILED6
20mA/div ALL LEDs AT 25.6mA SETTING 0A 1ms/div
ILED6 ALL LEDs AT 25.6mA SETTING 1ms/div
20mA/div 0A
LED STARTUP WAVEFORMS (VIN = 4V)
MAX8821 toc12
LED SHUTDOWN WAVEFORMS (VIN = 4V)
MAX8821 toc13
LED RAMP-UP
MAX8821 toc14
VIN
AC-COUPLED 50mV/div
VIN
AC-COUPLED 50mV/div
10mA/div
ILED6 IIN 50mA/div 0A IIN 50mA/div 0A 20mA/div 0A 1ms/div 400ms/div
0A 10mA/div
20mA/div ILED6 1ms/div 0A
ILED6
ILED5
0A
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9
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Typical Operating Characteristics (continued)
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = +25C, unless otherwise noted.) CLASS D AMP
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX8821 toc15
TOTAL HARMONIC DISTORTION vs. OUTPUT POWER
MAX8821 toc16
TOTAL HARMONIC DISTORTION vs. OUTPUT POWER
MAX8821 toc17
1 VIN = 3.6V RL = 8 POUT = 25mW THD+N (%)
100
100
10 THD+N (%) THD+N (%) VIN = 3.6V RL = 8 0.01
10
0.1
1
1
POUT = 350mW
0.1
0.1 VIN = 5V RL = 4 0.01 0 0.2 0.4 0.6 0.8 1.0 0 0.5 1.0 1.5 2.0 2.5 3.0 OUTPUT POWER (W) OUTPUT POWER (W)
POUT = 100mW 0.01 0.01 0.1 1 FREQUENCY (kHz) 10 100
SPREAD-SPECTRUM-MODE OUTPUT SPECTRUM vs. FREQUENCY
MAX8821 toc18
FIXED-FREQUENCY-MODE OUTPUT SPECTRUM vs. FREQUENCY
MAX8821 toc19
AUDIO AMPLIFIER GAIN vs. FREQUENCY
12.20 12.15 12.10 GAIN (dB) 12.05 12.00 11.95 11.90 11.85 11.80 11.75
MAX8821 toc20
20 0 -20 AMPLITUDE (dBV) -40 -60 -80 -100 -120 -140 0 5 10
RL = 8 VBATT = 5V VOUT = -60dBV UNWEIGHTED
20 0 -20 AMPLITUDE (dBV) -40 -60 -80 -100 -120 -140 RL = 8 VBATT = 5V VOUT = -60dBV UNWEIGHTED FFM -1100kHz
12.25
15
20
0
5
10 FREQUENCY (kHz)
15
20
0
5
10 FREQUENCY (kHz)
15
20
FREQUENCY (kHz)
AUDIO AMPLIFIER PHASE vs. FREQUENCY
MAX8821 toc21
AUDIO AMPLIFIER PSRR vs. FREQUENCY
MAX8821 toc22
WIDEBAND OUTPUT SPECTRUM SPREAD-SPECTRUM MODE
RL = 8 INPUTS AC GROUNDED
MAX8821 toc23
20 10 0
0 -10 -20 -30 PSRR (dB) -40 -50 -60 -70 -80 -90 -100 CCMREF = 1F 0.1 1 FREQUENCY (kHz) CCMREF = 0.1F VRIPPLE = 100mVP-P AUDIO GAIN = 0dB RL = 4
0 -20 AMPLITUDE (dBV) -40 -60 -80 -100 -120 -140 0.001
PHASE ()
-10 -20 -30 -40 -50 -60 0.1 1 10 100 FREQUENCY (kHz)
10
0.01
0.1
1
10
100
FREQUENCY (MHz)
10
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
Typical Operating Characteristics (continued)
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = +25C, unless otherwise noted.)
WIDEBAND OUTPUT SPECTRUM FIXED-FREQUENCY MODE
RL = 8 INPUTS AC GROUNDED
MAX8821 toc24
MAX8821
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX8821 toc25
0 -20 AMPLITUDE (dBV) -40 -60 -80 -100
2.5
2.0 OUTPUT POWER (W)
THD+N = 10%
1.5
1.0 THD+N = 1% 0.5
-120 RL = 8 -140 0.001 0 0.01 0.1 1 10 100 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 FREQUENCY (MHz) SUPPLY VOLTAGE (V)
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX8821 toc26
EFFICIENCY vs. SUPPLY VOLTAGE
95 90 EFFICIENCY (%) 85 80 75 70 65 60 RL = 4 RL = 8
MAX8821 toc27
3.5 3.0 THD+N = 10% OUTPUT POWER (W) 2.5 2.0 1.5 THD+N = 1% 1.0 0.5 RL = 4 0 2.7 3.1 3.5 3.9 4.3 4.7 5.1
100
55 50 5.5 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
EFFICIENCY vs. OUTPUT POWER
MAX8821 toc28
EFFICIENCY vs. OUTPUT POWER
90 80 EFFICIENCY (%) 70 60 50 40 30 20 RL = 4 RL = 8
MAX8821 toc29
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0 0.5 1.0 OUTPUT POWER (W) 1.5 VIN = 3.6V RL = 4 RL = 8
100
10 0 2.0 0 1 2 OUTPUT POWER (W) 3
VIN = 5V 4
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11
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Typical Operating Characteristics
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = +25C, unless otherwise noted.) DUAL LDOs
STARTUP WAVEFORMS
MAX8821 toc30
SHUTDOWN WAVEFORMS
MAX8821 toc31
AIN+ - AIN-
1V/div 0V
1V/div AIN+ - AIN0V
1V/div SPK+ - SPKAV = 0dB 0V SPK+ - SPKAV = 0dB
1V/div 0V
LDO DROPOUT VOLTAGE vs. LOAD CURRENT
180 160 DROPOUT VOLTAGE (mV) 140 120 100 80 60 40 20 0 0 50 100 150 200 250 300 LOAD CURRENT (mA) -5 0 LDO1 LDO2
MAX8821 toc32
LDO OUTPUT VOLTAGE ACCURACY vs. LOAD CURRENT
MAX8821 toc33
200
1 OUTPUT VOLTAGE ACCURACY (%) 0 -1 -2 -3 -4 VLDO2 = 2.8V
VLDO1 = 2.8V
50
100
150
200
250
300
LOAD CURRENT (mA)
LDO OUTPUT VOLTAGE vs. TEMPERATURE
MAX8821 toc34
LDO PSRR vs. FREQUENCY
-10 -20 -30 PSRR (dB) -40 -50 -60 -70 ILDO1 = 30mA ILDO2 = 20mA VIN-RIPPLE = 100mVP-P
MAX8821 toc35
2.90 2.85 OUTPUT VOLTAGE (V) 2.80 2.75 2.70 2.65 2.60 -40 -15 10 35 60 ILDO1 = 100mA ILDO1 = 0A ILDO2 = 0A
0
ILDO2 = 100mA
-80 -90 85 0.01 0.1 1 FREQUENCY (kHz) 10 100 TEMPERATURE (C)
12
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
Typical Operating Characteristics
(VIN1 = VIN2 = VIN3 = VDD = 3.6V, VAGND = VPGND1 = VPGND2 = 0V, circuit of Figure 2, TA = +25C, unless otherwise noted.)
MAX8821
LDO OUTPUT SPECTRUM
-20 -40 AMPLITUDE (dBV) -60 -80 VLDO1 -100 -120 VLDO2 -140 VIN
MAX8821 toc36
LDO LINE TRANSIENT (VIN3 = 3.6V TO 4.5V)
0
MAX8821 toc37
4.5V
3.6V AC-COUPLED 10mV/div
AC-COUPLED 10mV/div ILDO1 = 150mA, ILDO2 = 100mA
-160 0.001
0.01
0.1
1
10
100
1000
200s/div
FREQUENCY (kHz)
LDO1 LOAD TRANSIENT
MAX8821 toc38
LDO2 LOAD TRANSIENT
MAX8821 toc39
VLDO1
AC-COUPLED 50mV/div VLDO2 AC-COUPLED 50mV/div
50mA/div
50mA/div
ILDO1
0A
ILDO2 10s/div
0A
10s/div
LDO SHUTDOWN RESPONSE (LDO1, LDO2 UNLOADED)
MAX8821 toc40
VLDO1
1V/div
VLDO2
0V 1V/div
0V
2ms/div
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13
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Pin Description
PIN 1 2 3 4 5 6 7 8 NAME VDD CMREF AIN+ AINPGND2 SPKSPK+ IN2 FUNCTION I2C Input Supply Voltage. The VDD supply range is 1.5V to 5.5V. Drive VDD high to enable the I2C control. Drive VDD low to place the IC into shutdown mode. Audio Common-Mode Reference Voltage. Bypass CMREF with a 0.1F ceramic capacitor to AGND as close as possible to the IC. Noninverting Audio Input Inverting Audio Input Audio Amplifier Power Ground. Connect PGND2 to the system ground plane. Audio Amplifier Negative Output Audio Amplifier Positive Output Audio Amplifier Output Buffer Supply Voltage Input. The input voltage range is 2.7V to 5.5V. Connect IN2 directly to IN1 and IN3. Bypass IN2 to PGND2 with a 1F ceramic capacitor as close as possible to the IC. IN2 is high impedance during shutdown. 200mA LDO Output. Bypass LDO2 to AGND with a 1F ceramic capacitor. LDO2 is disabled through the I2C interface. 300mA LDO Output. Bypass LDO1 to AGND with a 2.2F ceramic capacitor. LDO1 is disabled through the I2C interface. I2C Clock Input. Data is read on the rising edge of VSCL. I2C Data Input. Data is read on the rising edge of VSCL.. Analog Ground. Connect AGND to the system ground plane. AGND is also internally connected to the exposed paddle. Reference Bypass. Bypass REF with a 0.1F ceramic capacitor to AGND as close as possible to the IC. LED Current Regulators. Current flowing into LED_ is based upon the internal I2C registers. Connect LED_ to the cathodes of the external LEDs. LED_ is high impedance during shutdown. If unused, short LED_ to IN1 to disable the regulator. Charge-Pump Negative Output. Connect a 1F ceramic capacitor from NEG to AGND. In shutdown, an internal 10k resistor connects NEG to AGND. Transfer Capacitor 2 Negative Connection. Connect a 1F ceramic capacitor from C2P to C2N. Transfer Capacitor 1 Negative Connection. Connect a 1F ceramic capacitor from C1P to C1N. Transfer Capacitor 2 Positive Connection. Connect a 1F ceramic capacitor from C2P to C2N. Transfer Capacitor 1 Positive Connection. Connect a 1F ceramic capacitor from C1P to C1N. Charge-Pump Supply Voltage Input. The input voltage range is 2.7V to 5.5V. Connect IN1 directly to IN2 and IN3. Bypass IN1 to PGND1 with a 2.2F ceramic capacitor as close as possible to the IC. IN1 is high impedance during shutdown. Charge-Pump Power Ground. Connect PGND1 to the system ground plane. Input Voltage Supply for LDO1, LDO2, REF, Class D Preamplifier, and Class D Amplifier Modulator Core. The input voltage range is 2.7V to 5.5V. Connect IN3 directly to IN1 and IN2. Bypass IN3 to AGND with a 2.2F ceramic capacitor as close as possible to the IC. IN3 is high impedance during shutdown. Exposed Paddle. Connect the exposed paddle to AGND directly under the IC. Exposed paddle is internally connected to AGND.
9 10 11 12 13 14 15-20
LDO2 LDO1 SCL SDA AGND REF LED1- LED6 NEG C2N C1N C2P C1P IN1 PGND1 IN3
21 22 23 24 25 26 27 28
--
EP
14
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
C1P C1N C2P C2N
IN1 PGND1 OSCILLATOR INVERTING CHARGE PUMP NEG
MAX8821
NEG
ADAPTIVE CURRENT REGULATORS
SELECT MINIMUM
LED1 CURRENT SOURCE CONTROL NEG
CMREF VDD SDA SCL I2C INTERFACE AND LOGIC CONTROL NEG
LED2
LED3 NEG
LDO1
LDO1 NEG
LED4
IN3
LDO2
LDO2 NEG
LED5
REF AGND REFERENCE OSCILLATOR IN3 AIN+ AIN-
LED6
IN2
SPK+ + PGA REF PGND2 EP PGND2 CLASS D AMP OUTPUT BUFFER SPK-
PGND2
Figure 1. Block Diagram
______________________________________________________________________________________
15
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
C8 1F C9 1F
C1P INPUT 2.7 TO 5.5V IN1 C7 2.2F
C1N
C2P
C2N
NEG PGND1 IN2
C6 1F
C3 1F
PGND2 IN3
LED1 LED2
C5 2.2F
AGND REF
MAX8821
LED3 LED4 LED5 LED6
C4 0.1F
INDIVIDUAL 0.1mA TO 25.6mA DIMMING
CMREF C12 0.1F LDO1 C10 2.2F C11 1F
VDD LOGIC CONTROL AND I2C INTERFACE SDA SCL
DUAL LOWNOISE LDO
LDO2
SPK+ DIFFERENTIAL AUDIO INPUT AIN+ SPKAINEP LOUDSPEAKER/EARPIECE
Figure 2. Typical Application Circuit
Detailed Description
The MAX8821 integrates a charge pump for white LED display backlighting, an audio loudspeaker amplifier, and dual LDO for camera functions. It includes softstart, thermal shutdown, open-circuit and short-circuit protections for the white LEDs, audio amplifier, and LDOs. Figure 1 is the block diagram, and Figure 2 shows the typical application circuit.
LED Charge Pump
The MAX8821 features an inverting charge pump and six current regulators capable of 25.6mA each to drive
16
six LEDs. The current regulators are matched to within 1% (typ), providing uniform white LED brightness for LCD backlight applications. To maximize efficiency, the current regulators operate with as little as 0.15V voltage drop. Individual white LED current regulators conduct current to GND or NEG to extend usable battery life. In the case of mismatched forward voltage of white LEDs, only the white LEDs requiring higher voltage are switched to direct current to NEG instead of GND, further raising efficiency and reducing battery current drain. The regulation scheme is optimized to ensure low EMI and low input ripple. The on-chip ambient temperature derating function safely allows bright 25.6mA
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
full-scale output current while automatically reducing current gradually above +40C in accordance with popular LED ratings. The on-chip derating feature can be enabled, or disabled, using the I2C interface. LED_ current not returning to 0mA during the off time. See the following equations to ensure proper operation: tLED _ RU t ON _ BLINK (LED _[4 : 0] + 1) 32 tLED _ RD t OFF _ BLINK (LED _[4 : 0] + 1) 32 where LED_[4:0] is the programmed current set by I2C (see Tables 6 and 7). Figure 6 shows combining ramp function and blink timer.
MAX8821
Current Regulator Switchover When VIN is higher than the forward voltage of the white LED plus the 0.15V headroom of the current regulator, the LED current returns through ground. If this condition is satisfied for all six white LEDs the charge pump remains inactive. When the input voltage drops so that the current regulator head room cannot be maintained for any of the individual white LEDs, the inverting charge pump activates and generates a voltage on NEG that is no greater than 5V below VIN. Each current regulator contains circuitry that detects when it is in dropout and switches that current regulator return path from GND to NEG. Since this is done on an LED-byLED basis, the LED current is switched for only the individual LED requiring higher voltage, thus minimizing power consumption. Ramp-Up and Ramp-Down Function The LED drivers in the MAX8821 provide ramp-up and ramp-down of LED current for smooth transitions between different brightness settings. A controlled ramp is used when the LED current level is changed, when the LEDs are enabled, and when the LEDs are disabled. The LED currents ramp up and down smoothly on a pseudo-log scaling of the LED current sources (Figures 3 and 4). Each LED source has an individual ramp control making it possible to ramp different LEDs at different rates. The ramp-up and ramp-down (tRAMP) LED current times are controlled by the LED_RU and LED_RD control bits (Tables 8, 9, and 10). The LED_RP_EN bit enables and disables the ramps. The MAX8821 increases/decreases the current one step every tRAMP/32 until the desired current is reached. Blink Timer The current regulators for LED5 and LED6 feature a blink function. The OFF and ON time for LED5 and LED6 can be set using the I2C interface (Table 11). See Figure 5. Combining Blink Timer and Ramp Function To combine the ramp function together with the blink timer for LED5 and/or LED6, special timing considerations need to be fulfilled. It is recommended to keep the ramp-up timer shorter than the ON blink timer and the ramp-down timer shorter than the OFF blink timer. Failing to comply with these timing constraints results in the LED_ not reaching the programmed current (LED_[4:0], Tables 6 and 7) during the ON time and the
LED Short- and Open-Circuit Protection If any LED fails as an open circuit, the corresponding LED_ is internally connected to ground and the charge pump is enabled. To disable the corresponding current regulator, short any unused LED_ to IN1. The MAX8821 contains special circuitry to detect this condition and disables the corresponding current regulator to avoid wasting battery power. Temperature Derating The MAX8821 contains a derating function that automatically limits the LED current at high temperatures in accordance with the recommended derating curve of popular white LEDs. The derating function enables the safe usage of higher LED current at room temperature, thus reducing the number of LEDs required to backlight the display. The derating circuit limits the LED current by reducing the LED current above +40C at approximately 1.67%/C. The temperature derating function is enabled/disabled using the I2C interface and by default is disabled.
tRAMP = tRAMP = 262ms 524ms tRAMP = 1048ms tRAMP = 2097ms
ILED_ = 25.6mA
ILED_ = 0
Figure 3. Ramp-Up Behavior
ILED_ = 25.6mA
ILED_ = 0
tRAMP = 262ms
tRAMP = 524ms
tRAMP = 1048ms
tRAMP = 2097ms
Figure 4. Ramp-Down Behavior
17
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Audio Amplifier
The audio amplifier in the MAX8821 is a 2W Class D loudspeaker amplifier. The amplifier features a lowpower shutdown mode and industry-leading click-andpop suppression. The amplifier also features a programmable gain control through an I2C interface. The amplifier operates from a single 2.7V to 5.5V supply (VIN3 = VIN2) and features an internally generated common-mode bias voltage of VIN3 / 2 referenced to ground.
ILED5[4:0]
ILED6[4:0]
0.512s = tOFF_BLINK = 4.098s
64ms = tON_BLINK = 512ms
Click-and-Pop Suppression The MAX8821 features Maxim's industry-leading clickand-pop suppression circuitry. During startup, the amplifier's common-mode bias voltage ramps to the DC bias point. When entering shutdown, the amplifier outputs are high impedance with 100k between both inputs. This scheme minimizes the energy present in the audio band. Class D Amplifier The MAX8821 ultra-low-EMI, filterless, Class D audio power amplifier features several improvements to switch mode amplifier technology. The MAX8821 audio amplifier features output driver AEL circuitry to reduce EMI. Zero dead-time technology maintains state-of-theart efficiency and THD+N performance by allowing the output MOSFETs to switch simultaneously without cross-conduction. A unique filterless modulation scheme and spreadspectrum mode create a compact, flexible, low-noise, efficient audio power amplifier while occupying minimal board space. The differential input architecture reduces common-mode noise pickup with or without the use of input-coupling capacitors. The MAX8821 audio amplifier can also be configured as a single-ended input amplifier without performance degradation. The input capacitors CIN (Figure 7) are required for single-ended input applications and are typically 1F. The output of the MAX8821 shuts down if the output current reaches approximately 2A. Each output MOSFET has its own short-circuit protection. This protection scheme allows the amplifier to survive shorts to either supply rail. After a thermal overload or short circuit, the device remains disabled for a minimum of 110s before attempting to return to normal operation. The amplifier shuts down immediately and waits another 110s before turning on if the fault condition remains. This operation causes the output to pulse during a persistent fault. Comparators monitor the MAX8821 inputs and compare the complementary input voltages to the sawtooth waveform. The comparators trip when the input magnitude of the sawtooth exceeds their corresponding input voltage.
18
Figure 5. Blink Timer Behavior
Both comparators reset at a fixed time after the rising edge of the second comparator trip point, generating a minimum width pulse tON(MIN) at the output of the second comparator. As the input voltage increases or decreases, the duration of the pulse at one output increases (the first comparator to trip), while the other output pulse duration remains at tON(MIN). This causes the net voltage across the speaker (SPK+ - SPK-) to change.
Adjustable Differential Gain The audio amplifier has an internal gain control. The gain of the input amplifiers is controlled through the I2C interface. The gain setting of the input amplifier can be set from -3dB to +24dB (Table 15). This allows the amplifier to be used for both hands-free and for receiver mode without any external components. Input Filter The fully differential amplifier inputs can be biased at voltages other than midsupply. The common-mode feedback circuit adjusts for input bias, ensuring the outputs are still biased at midsupply. Input capacitors are not required as long as the common-mode input voltage is within the specified range listed in the Electrical Characteristics table. If input capacitors are used, input capacitor CIN, in conjunction with on-chip RINT, forms a highpass filter that removes the DC bias from an incoming signal. The AC-coupling capacitor allows the amplifier to bias the signal to an optimum DC level. Assuming zero-source impedance, the -3dB point of the highpass filter is given by:
f -3dB = 1 2 x x RINT x CIN
Setting the -3dB corner too high affects the low-frequency response of the amplifier. Use capacitors with dielectrics that have low-voltage coefficients, such as aluminum electrolytic. Capacitors with high voltage coefficients, such as ceramics, can increase distortion at low frequencies.
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
tOFF_BLINK tON_BLINK tOFF_BLINK
ILED_ = LED_ [4.0]
ILED_ = 0mA t = tLED_RU/32 t = tLED_RD/32
Figure 6. Combining Ramp Function and Blink Timer (Tables 10 and 11)
LDO1 and LDO2
The linear regulators are designed for low dropout and low quiescent current to maximize battery life. Both LDOs are controlled through the I2C interface, minimizing the number of control lines to the MAX8821. Each LDO has an individual control register (LDO1_CNTL and LDO2_CNTL, Tables 13 and 14). The I2C interface controls the output voltages, and the enable/disable state for both LDO1 and LDO2.
RINT CIN AUDIO INPUTS CIN RINT
MAX8821
MONO CLASS D AUDIO AMP EARPIECE/ LOUDSPEAKER
Figure 7. Optional Input Capacitors
Thermal Shutdown
The MAX8821 includes a thermal-limit circuit that shuts down the IC at a junction temperature of approximately +160C. The IC turns on after it cools by approximately 20C. is 8 bits long and is always followed by an acknowledge clock pulse (K). Both SCL and SDA remain high when the interface is not busy. A master signals the beginning of a transmission with a START (A) condition by transitioning SDA from high to low while SCL is high. When the master has finished communicating with the slave, the master issues a STOP (L) condition by transitioning SDA from low to high while SCL is high. The bus is then free for another transmission. One data bit is transferred during each clock pulse. The data on SDA must remain stable while SCL is high.
Shutdown Mode
The MAX8821 can be put into two different shutdown modes. The first shutdown mode is achieved by driving VDD low. In this mode, the I2C interface becomes disabled. The second shutdown is a lower power mode. To enter the low-power mode, disable LED_, audio amplifier, and LDOs through I2C. In lower power mode, the I2C interface is still active.
I2C Interface
The I2C serial interface consists of a serial-data line (SDA) and a serial-clock line (SCL). Standard I2C writebyte commands are used. Figure 8 shows a timing diagram for the I2C protocol. The MAX8821 is a slave-only device, relying upon a master to generate a clock signal. The master (typically a microprocessor) initiates data transfer on the bus and generates SCL to permit data transfer. A master device communicates to the MAX8821 by transmitting the proper 8-bit address followed by the 8-bit control byte. Each transmit sequence is framed by a START (A) condition and a STOP (L) condition. Each word transmitted over the bus
Register Reset The I2C register is reset back to the default value when either VIN_ drops below the UVLO threshold or VDD is driven low. I2C Registers and Control I2C Address The MAX8821 acts as a slave transmitter/receiver. The slave address of the MAX8821 is preset to 1001110X, where "X" is the R/W bit. The address 0x9C is designated for write operations and 0x9D for read operations. Use Table 1 as a register map to reference the control bits found in Tables 2-16.
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19
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
A tLOW B tHIGH C D E F G H I J K L M
SCL
SDA
tSU_STA tHD_STA
tSU_DAT
tHD_DAT F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO SLAVE (OP/SUS BIT) H = LSB OF DATA CLOCKED INTO SLAVE I = SLAVE PULLS SMBDATA LINE LOW
tSU_STO tBUF J = ACKNOWLEDGE CLOCKED INTO MASTER K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION, DATA EXECUTED BY SLAVE M = NEW START CONDITION
A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW
Figure 8. I2C Timing Diagram
Table 1. Register Map
NAME LED1_CNTL LED2_CNTL LED3_CNTL LED4_CNTL LED5_CNTL LED6_CNTL RAMP1_CNTL RAMP2_CNTL RAMP3_CNTL BLINK_CNTL LED_EN LDO1_CNTL LDO2_CNTL AUDIO_CNTL PUMP_CNTL GROUP ADDRESS (hexadecimal) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E TABLE 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 TYPE R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W DESCRIPTION LED1 current regulator control LED2 current regulator control LED3 current regulator control LED4 current regulator control LED5 current regulator control LED6 current regulator control LED1 and LED2 ramp control LED3 and LED4 ramp control LED5 and LED6 ramp control LED5 and LED6 blink control LED1-LED6 enable control LDO1 control LDO2 control Audio amplifier, control clock, and frequency Charge-pump control setting and temperature derating enable/disable
20
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Table 2. LED1_CNTL (Address 0x00)
BIT B7, B6 NAME N/A, do not use. 0 1 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 B4-B0 LED1[4:0] 01111 10000 10001 10010 10011 10100 10101 10110 10111 11000 11001 11010 11011 11100 11101 11110 11111 LED1 ramp-up/down disabled. LED1 ramp-up/down enabled. 0.1mA 0.2mA 0.3mA 0.4mA 0.5mA 0.6mA 0.7mA 0.8mA 1.0mA 1.2mA 1.4mA 1.6mA 2.0mA 2.4mA 2.8mA 3.2mA 4.0mA 4.8mA 5.6mA 6.4mA 8.0mA 9.6mA 11.2mA 12.8mA 14.4mA 16.0mA 17.6mA 19.2mA 20.8mA 22.4mA 24.0mA 25.6mA B4-B0 LED2[4:0] CODE DESCRIPTION
Table 3. LED2_CNTL (Address 0x01)
BIT B7, B6 NAME N/A, do not use. 0 1 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 10010 10011 10100 10101 10110 10111 11000 11001 11010 11011 11100 11101 11110 11111 LED2 ramp-up/down disabled. LED2 ramp-up/down enabled. 0.1mA 0.2mA 0.3mA 0.4mA 0.5mA 0.6mA 0.7mA 0.8mA 1.0mA 1.2mA 1.4mA 1.6mA 2.0mA 2.4mA 2.8mA 3.2mA 4.0mA 4.8mA 5.6mA 6.4mA 8.0mA 9.6mA 11.2mA 12.8mA 14.4mA 16.0mA 17.6mA 19.2mA 20.8mA 22.4mA 24.0mA 25.6mA CODE DESCRIPTION
B5
LED1_RP_EN
B5
LED2_RP_EN
Note: Defaults in bold italics.
Note: Defaults in bold italics.
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Table 4. LED3_CNTL (Address 0x02)
BIT B7, B6 NAME N/A, do not use. 0 1 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 B4-B0 LED3[4:0] 01111 10000 10001 10010 10011 10100 10101 10110 10111 11000 11001 11010 11011 11100 11101 11110 11111 LED3 ramp-up/down disabled. LED3 ramp-up/down enabled. 0.1mA 0.2mA 0.3mA 0.4mA 0.5mA 0.6mA 0.7mA 0.8mA 1.0mA 1.2mA 1.4mA 1.6mA 2.0mA 2.4mA 2.8mA 3.2mA 4.0mA 4.8mA 5.6mA 6.4mA 8.0mA 9.6mA 11.2mA 12.8mA 14.4mA 16.0mA 17.6mA 19.2mA 20.8mA 22.4mA 24.0mA 25.6mA B4-B0 LED4[4:0] CODE DESCRIPTION
Table 5. LED4_CNTL (Address 0x03)
BIT B7, B6 NAME N/A, do not use. 0 1 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 10010 10011 10100 10101 10110 10111 11000 11001 11010 11011 11100 11101 11110 11111 LED4 ramp-up/down disabled. LED4 ramp-up/down enabled. 0.1mA 0.2mA 0.3mA 0.4mA 0.5mA 0.6mA 0.7mA 0.8mA 1.0mA 1.2mA 1.4mA 1.6mA 2.0mA 2.4mA 2.8mA 3.2mA 4.0mA 4.8mA 5.6mA 6.4mA 8.0mA 9.6mA 11.2mA 12.8mA 14.4mA 16.0mA 17.6mA 19.2mA 20.8mA 22.4mA 24.0mA 25.6mA CODE DESCRIPTION
B5
LED3_RP_EN
B5
LED4_RP_EN
Note: Defaults in bold italics.
Note: Defaults in bold italics.
22
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Table 6. LED5_CNTL (Address 0x04)
BIT B7, B6 NAME N/A, do not use. 0 1 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 B4-B0 LED5[4:0] 01111 10000 10001 10010 10011 10100 10101 10110 10111 11000 11001 11010 11011 11100 11101 11110 11111 LED5 ramp-up/down disabled. LED5 ramp-up/down enabled. 0.1mA 0.2mA 0.3mA 0.4mA 0.5mA 0.6mA 0.7mA 0.8mA 1.0mA 1.2mA 1.4mA 1.6mA 2.0mA 2.4mA 2.8mA 3.2mA 4.0mA 4.8mA 5.6mA 6.4mA 8.0mA 9.6mA 11.2mA 12.8mA 14.4mA 16.0mA 17.6mA 19.2mA 20.8mA 22.4mA 24.0mA 25.6mA B4-B0 LED6[4:0] CODE DESCRIPTION
Table 7. LED6_CNTL (Address 0x05)
BIT B7, B6 NAME N/A, do not use. 0 1 00000 00001 00010 00011 00100 00101 00110 00111 01000 01001 01010 01011 01100 01101 01110 01111 10000 10001 10010 10011 10100 10101 10110 10111 11000 11001 11010 11011 11100 11101 11110 11111 LED6 ramp-up/down disabled. LED6 ramp-up/down enabled. 0.1mA 0.2mA 0.3mA 0.4mA 0.5mA 0.6mA 0.7mA 0.8mA 1.0mA 1.2mA 1.4mA 1.6mA 2.0mA 2.4mA 2.8mA 3.2mA 4.0mA 4.8mA 5.6mA 6.4mA 8.0mA 9.6mA 11.2mA 12.8mA 14.4mA 16.0mA 17.6mA 19.2mA 20.8mA 22.4mA 24.0mA 25.6mA CODE DESCRIPTION
B5
LED5_RP_EN
B5
LED6_RP_EN
Note: Defaults in bold italics.
Note: Defaults in bold italics.
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Table 8. RAMP1_CNTL (Address 0x06)
BIT B7, B6 B5, B4 B3, B2 B1, B0 NAME LED1_RU[1:0] LED1_RD[1:0] LED2_RU[1:0] LED2_RD[1:0] DESCRIPTION LED1 ramp-up control LED1 ramp-down control LED2 ramp-up control LED2 ramp-down control CODE 00 01 10 11 RAMP TIME (tRAMP) (ms) 218 x TQPCLK 219 x TQPCLK 220 x TQPCLK 221 x TQPCLK
Notes: TQPCLK = 1 / fSW ; defaults in bold italics.
Table 9. RAMP2_CNTL (Address 0x07)
BIT B7, B6 B5, B4 B3, B2 B1, B0 NAME LED3_RU[1:0] LED3_RD[1:0] LED4_RU[1:0] LED4_RD[1:0] DESCRIPTION LED3 ramp-up control LED3 ramp-down control LED4 ramp-up control LED4 ramp-down control CODE 00 01 10 11 RAMP TIME (tRAMP) (ms) 218 x TQPCLK 219 x TQPCLK 220 x TQPCLK 221 x TQPCLK
Notes: TQPCLK = 1 / fSW ; defaults in bold italics.
Table 10. RAMP3_CNTL (Address 0x08)
BIT B7, B6 B5, B4 B3, B2 B1, B0 NAME LED5_RU[1:0] LED5_RD[1:0] LED6_RU[1:0] LED6_RD[1:0] DESCRIPTION LED5 ramp-up control LED5 ramp-down control LED6 ramp-up control LED6 ramp-down control CODE 00 01 10 11 RAMP TIME (tRAMP) (ms) 218 x TQPCLK 219 x TQPCLK 220 x TQPCLK 221 x TQPCLK
Notes: TQPCLK = 1 / fSW ; defaults in bold italics.
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Table 11. BLINK_CNTL (Address 0x09)
BIT NAME CODE 00 B7, B6 LED5_OFF_BLINK 01 10 11 00 B5, B4 LED5_ON_BLINK 01 10 11 00 B3, B2 LED6_OFF_BLINK 01 10 11 00 B1, B0 LED6_ON_BLINK 01 10 11 BLINK TIME 219 x TQPCLK 220 x TQPCLK 221 x TQPCLK 222 x TQPCLK 216 x TQPCLK 217 x TQPCLK 218 x TQPCLK 219 x TQPCLK 219 x TQPCLK 220 x TQPCLK 221 x TQPCLK 222 x TQPCLK 216 x TQPCLK 217 x TQPCLK 218 x TQPCLK 219 x TQPCLK B3-B0 LDO1[3:0] B4 LDO1_PD 1 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 BIT B7 B6 B5 B4 NAME LED1_EN LED2_EN LED3_EN LED4_EN CODE 0 1 00 B3, B2 LED5_EN[1:0] 01 LED current source is enabled. LED current source controlled by blink timer. N/A, do not use. DESCRIPTION LED current source is disabled. LED current source is enabled. LED current source is disabled. 1110 1111 Active pulldown disabled during OFF condition. 1.2V 1.3V 1.5V 1.6V 1.8V 1.9V 2.0V 2.3V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V
Table 13. LDO1_CNTL (Address 0x0B)
BIT B7, B6 B5 NAME CODE 0 1 0 DESCRIPTION LDO1 is disabled. LDO1 is enabled. Active pulldown enabled during OFF condition. N/A, do not use. LDO1_EN
Notes: TQPCLK = 1 / fSW ; defaults in bold italics.
Table 12. LED_EN (Address 0xA)
Note: Defaults in bold italics.
B1, B0
LED6_EN[1:0]
10 11
Note: Defaults in bold italics.
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Table 14. LDO2_CNTL (Address 0x0C)
BIT B7, B6 B5 NAME CODE 0 1 0 B4 LDO2_PD 1 0000 0001 0010 0011 0100 0101 0110 B3-B0 LDO2[3:0] 0111 1000 1001 1010 1011 1100 1101 1110 1111 Active pulldown disabled during OFF condition. 1.5V 1.6V 1.8V 2.0V 2.2V 2.3V 2.4V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V 0000 0001 0010 0011 0100 0101 0110 B3-B0 AUDIO_GAIN[3:0] 0111 1000 1001 1010 1011 1100 1101 1110 1111 B4 AMP_EN 0 1 11 01 B6, B5 CLK_CNTL[1:0] 10 00 1 DESCRIPTION LDO2 is disabled. LDO2 is enabled. Active pulldown enabled during OFF condition. B7 SYNC N/A, do not use. LDO2_EN 0
Table 15. AUDIO_CNTL (Address 0x0D)
BIT NAME CODE DESCRIPTION Audio amplifier and charge-pump clocks are not synchronized. Audio amplifier and charge-pump clocks are synchronized. Charge pump oscillator clock = audio clock / 2. Oscillator frequency 1100kHz, fixedfrequency mode. Oscillator frequency 1400kHz, fixedfrequency mode. Oscillator frequency 1250kHz, spreadspectrum mode. Reserved for future use. Class D amplifier is disabled. Class D amplifier is enabled. -3dB 0dB 3dB 6dB 9dB 12dB 15dB 18dB 21dB 24dB N/A, do not use. N/A, do not use. N/A, do not use. N/A, do not use. N/A, do not use. N/A, do not use.
Note: Defaults in bold italics.
Note: Defaults in bold italics.
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
Table 16. PUMP_CNTL (Address 0x0E)
BIT B7-B3 NAME N/A, do not use 0 B2 TEMP_DR 1 Temperature derating disabled. Temperature derating enabled. Charge pump automatically changes between 1x/1.5x mode. Charge pump is forced into 1.5x mode regardless of input voltage. Charge pump is forced into 1.5x mode regardless of input voltage when audio amplifier is enabled. If the amplifier is not enabled, the charge pump automatically switches between 1x mode and 1.5x mode. N/A, do not use. CODE DESCRIPTION
Applications Information
PCB Layout
PCB layout is essential for optimizing performance. Use large traces for the power-supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance and to route heat away from the device. To avoid potential noise to the differential input audio signal and differential output audio signal, route the negative and positive traces in parallel. Also, avoid placing any RF or high-speed data signals in parallel to the audio signals. In some applications, such as GSM, extra noise reduction may be needed. To reduce the risk of noise, place 16pF ceramic capacitors from AIN+ to AGND, AIN- to AGND, OUT+ to AGND, OUT- to AGND, OUT+ to OUT-, and AIN+ to AIN-. Proper grounding improves audio performance and prevents any digital switching noise from coupling into the audio signal. The Thin QFN package features an exposed thermal paddle on its undersides. This paddle lowers the thermal resistance of the package by providing a direct-heat conduction path from the die to the PCB. Connect the exposed paddle to AGND directly under the IC. Refer to the MAX8821 Evaluation Kit for an example of a PCB layout.
MAX8821
00
01
B1, B0
PUMP_CNTL [1:0]
10
11
Note: Defaults in bold italics.
Pin Configuration
PROCESS: BiCMOS
LED6 LED4 LED3 LED2 LED5 LED1 NEG
Chip Information
TOP VIEW
21 C2N 22 C1N 23 C2P 24 C1P 25 IN1 26 PGND1 27
20
19
18
17
16
15 14 13 12 REF AGND SDA SCL LDO1 LDO2 IN2
MAX8821ETI+
11 10 9
EP = EXPOSED PADDLE IN3 28 + 1 VDD 2 CMREF 3 AIN+ 4 AIN5 PGND2 6 SPK7 SPK+ 8
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO MAX8821
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
24L QFN THIN.EPS
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White LED Charge Pump with Mono Class D Audio Amp and Dual LDO
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
MAX8821
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 29
(c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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