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19-2338; Rev 2; 12/02
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown
General Description
The MAX4366/MAX4367/MAX4368 are bridged audio power amplifiers intended for devices with internal speakers and headsets. The MAX4366/MAX4367/ MAX4368 are capable of delivering 330mW of continuous power into a 32 load, or 200mW into a 16 load with 1% THD+N from a single 5V supply. The MAX4366/MAX4367/MAX4368 bridged outputs eliminate the need for output-coupling capacitors minimizing external component count. The MAX4366/MAX4367/ MAX4368 also feature a low-power shutdown mode, clickless power-up/power-down and internal DC bias generation. The MAX4366 is a unity-gain stable, programmable gain amplifier. The MAX4367/MAX4368 feature internally preset gains of 2V/V and 3V/V, respectively. All devices are available in space-saving 8-pin SOT23, thin QFN and MAX packages, and an 8-bump chipscale package (UCSPTM).
Features
o Drives 330mW into 32 (200mW into 16) o 0.02% THD+N at 1kHz (120mW into 32) o Internal Bridged Configuration o o o o No Output-Coupling Capacitors 2.3V to 5.5V Single-Supply Operation 2mA Supply Current Low-Power Shutdown Mode
MAX4366/MAX4367/MAX4368
o Clickless Power-Up and Shutdown o Thermal Overload Protection o Available in SOT23, Thin QFN, MAX, and UCSP Packages
Ordering Information
PART TEMP RANGE PIN/BUMPPACKAGE 8 UCSP-8 8 SOT23-8 8 MAX 8 Thin QFN-EP* TOP MARK AAK AAIO -- AAC
Applications
Cellular Phones Two-Way Radios PDAs Headphones Headsets General-Purpose Audio
MAX4366EBL-T -40C to +85C MAX4366EKA-T -40C to +85C MAX4366EUA MAX4366ETA -40C to +85C -40C to +85C
*EP = Exposed paddle. Ordering Information continued at end of data sheet. Selector Guide and Functional Diagrams appear at end of data sheet.
Pin Configurations
TOP VIEW (BUMP SIDE DOWN)
1 A INOUT+ IN+ 2 3
Typical Operating Circuit
VCC
VCC BIAS
CLICKLESS/POPLESS SHUTDOWNCONTROL
SHDN
OUTB GND
MAX4366 MAX4367 MAX4368
VCC
IN+ AUDIO INPUT OUT+ IN-
C
BIAS
OUT-
SHDN
UCSP
MAX4367 MAX4368
GND
Pin Configurations continued at end of data sheet. UCSP is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..............................................................-0.3V to +6V IN+, IN-, BIAS, SHDN.................................-0.3V to (VCC + 0.3V) Output Short Circuit to VCC or GND (Note 1).............Continuous Output Short Circuit (OUT+ to OUT-) (Note 1)...........Continuous Continuous Power Dissipation (TA = +70C) 8-Bump UCSP (derate 4.7mW/C above +70C)..........379mW 8-Pin SOT23 (derate 9.7mW/C above +70C).............777mW 8-Pin MAX (derate 4.5mW/C above +70C) ..............362mW 8-Pin Thin QFN (derate 24.4mWC above +70C) .....1951mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Bump Temperature (soldering) (Note 2) Infrared (15s) ................................................................+220C Vapor Phase (60s) ........................................................+215C
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
(VCC = 5V, RL = , RIN = RF = 30k, CBIAS = 1F to GND, SHDN = GND, IN+ = BIAS, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 3)
PARAMETER Supply Voltage Range Supply Current Shutdown Supply Current SHDN Threshold SHDN Input Bias Current Common-Mode Bias Voltage VBIAS (Note 5) MAX4366, RIN = Output Offset Voltage VOS MAX4367, IN- = open MAX4368, IN- = open MAX4366 (open loop) Differential Voltage Gain AV (Note 6) MAX4367 (internally set) MAX4368 (internally set) Input Common-Mode Range Differential Input Resistance Input Resistance Power-Supply Rejection Ratio Common-Mode Rejection Ratio PSRR CMRR VCM RIN(DIFF) MAX4366, VIN+ - VIN- = 10mV VIN- = 0V to VCC (MAX4367/MAX4368) VCC = 2.3V to 5.5V TA = +25C TA = TMIN to TMAX 70 66 80 87 125 mA 115 60 120 200 mW RL = 32 330 0.3 500 20 80 5 VCC/2 - 5% SYMBOL VCC ICC ISHDN VIH VIL -400 VCC/2 5 5 7.5 100 2 3 VCC 1.0 VCC/2 + 5% 15 15 15 dB V/V V k k dB dB mV (Note 4) SHDN = VCC 1.8 0.8 CONDITIONS Inferred from PSRR test MIN 2.3 2 35 TYP MAX 5.5 4.3 100 UNITS V mA A V nA V
0V VCM VCC - 1.0V (MAX4366) 2.7V VCC 5.5V, 0.6V VOUT VCC - 0.6V 2.3V VCC 2.7V, 0.6V VOUT VCC - 0.6V
Output Source/Sink Current
IOUT
(Note 7)
Output Power
PO
f = 1kHz, THD+N <1% (Note 8)
RL = 16
2
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330mW, Ultra-Small, Audio Power Amplifiers with Shutdown
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 5V, RL = , RIN = RF = 30k, CBIAS = 1F to GND, SHDN = GND, IN+ = BIAS, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 3)
PARAMETER Total Harmonic Distortion Plus Noise Noise Short-Circuit Current Thermal Shutdown Threshold Thermal Shutdown Hysteresis Power-Up Time Shutdown Time Enable Time from Shutdown tPU tSHDN tENABLE ISC SYMBOL THD+N CONDITIONS AV = -2V/V, f = 1kHz (MAX4366) (Notes 9 and 10) PO = 60mW, RL = 16 PO = 120mW, RL = 32 MIN TYP 0.04 % 0.02 20 185 215 165 10 60 20 60 0.15 nV/Hz mA C C ms ms ms MAX UNITS
MAX4366/MAX4367/MAX4368
f = 10kHz, referred to input To VCC To GND
Note 1: Continuous power dissipation must also be observed. Note 2: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be exposed to during board-level solder attach and rework. This limit permits only the use of the solder profiles recommended in the industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and convection reflow. Preheating is required. Hand or wave soldering is not allowed. Note 3: All specifications are 100% tested at TA = +25C; temperature limits are guaranteed by design. Note 4: Quiescent power-supply current is specified and tested with no load on the outputs. Quiescent power-supply current depends on the offset voltage when a practical load is connected to the amplifier. Note 5: Common-mode bias voltage is the voltage on BIAS and is nominally VCC/2. Note 6: Differential voltage gain for the MAX4366 is specified as an open-loop parameter because external resistors are used to set the closed-loop gain. The MAX4367/MAX4368 contain internal feedback resistors that preset the differential voltage gain. Differential voltage gain is defined as (VOUT+ - VOUT-) / (VIN - VBIAS). All gains are specified over an output voltage range of 0.6V VOUT 4.4V. Note 7: Specification applies to either output. An amplifier peak output current of 87mA is required to support an output load power of 60mW for a 16 load, or 120mW for a 32 load. Note 8: Output power specifications are inferred from the output current test. For 60mW into a 16 load, IOUT(PEAK) is 87mA and VOUT(P-P) is 1.39V per amplifier. For 120mW into a 32 load, IOUT(PEAK) is 87mA and VOUT(P-P) is 2.77V per amplifier. Note 9: Guaranteed by design. Not production tested. Note 10: Measurement bandwidth for THD+N is 20Hz to 20kHz. Note 11: Power-up and shutdown times are for the output to reach 90% of full scale with CBIAS = 1F.
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3
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
Typical Operating Characteristics
(Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 5V AV = 2V/V RL = 16 POUT = 10mW 0.1 THD+N (%) THD+N (%)
MAX4366 toc01
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 5V AV = 3V/V RL = 16 POUT = 10mW 0.1 THD+N (%)
MAX4366 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc03
1
1
1 POUT = 10mW 0.1
0.01 POUT = 60mW
POUT = 25mW
POUT = 25mW 0.01 POUT = 60mW
POUT = 25mW 0.01 POUT = 60mW VCC = 5V AV = 4V/V RL = 16
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 5V AV = 3V/V RL = 32 0.1 THD+N (%)
MAX4366 toc06
1
1 VCC = 5V AV = 2V/V RL = 32 0.1 THD+N (%)
1
POUT = 10mW 0.1 THD+N (%) POUT = 60mW POUT = 25mW
POUT = 50mW 0.01 POUT = 75mW
POUT = 50mW 0.01 POUT = 75mW POUT = 120mW 0.001
0.01 VCC = 5V AV = 20V/V RL = 16 0.001 10 100 1k FREQUENCY (Hz) 10k 100k
POUT = 120mW 0.001 10 100 1k FREQUENCY (Hz) 10k 100k
10
100
1k FREQUENCY (Hz)
10k
100k
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc07
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc08
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 3V AV = 2V/V RL = 16 0.1 THD+N (%) POUT = 10mW
MAX4366 toc09
1 VCC = 5V AV = 4V/V RL = 32 0.1 THD+N (%) POUT = 50mW POUT = 75mW
1 POUT = 50mW
1
0.1 THD+N (%) POUT = 75mW
POUT = 120mW 0.01
0.01 POUT = 120mW
0.01 VCC = 5V AV = 20V/V RL = 32 POUT = 60mW
POUT = 25mW
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
4
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330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
Typical Operating Characteristics (continued)
(Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc10
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc11
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc12
1 VCC = 3V AV = 3V/V RL = 16 0.1 THD+N (%) POUT = 10mW
1 POUT = 10mW 0.1 THD+N (%) POUT = 25mW
1
POUT = 60mW 0.1 THD+N (%) POUT = 10mW POUT = 25mW
POUT = 60mW 0.01 VCC = 3V AV = 4V/V RL = 16
0.01
POUT = 25mW POUT = 60mW
0.01 VCC = 3V AV = 20V/V RL = 16 0.001 10 100 1k FREQUENCY (Hz) 10k 100k 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc13
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc14
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 3V AV = 4V/V RL = 32
MAX4366 toc15
1 VCC = 3V AV = 2V/V RL = 32
1 VCC = 3V AV = 3V/V RL = 32 0.1 THD+N (%) POUT = 10mW
1
POUT = 10mW 0.1 THD+N (%) POUT = 25mW 0.01 POUT = 50mW
POUT = 10mW 0.1 THD+N (%) POUT = 25mW
POUT = 25mW
0.01 POUT = 50mW
0.01
POUT = 50mW
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4366 toc16
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4366 toc17
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4366 toc18
1 POUT = 10mW POUT = 25mW 0.1 THD+N (%)
100
100
10
f = 10kHz
10
THD+N (%)
POUT = 50mW
1 f = 1kHz
THD+N (%)
1
f = 10kHz
0.1
0.1
0.01 VCC = 3V AV = 20V/V RL = 32 0.001 10 100 1k FREQUENCY (Hz) 10k 100k 0.01 VCC = 5V AV = 2V/V RL = 16 0 100 200 300 400 0.01 f = 1kHz VCC = 5V AV = 4V/V RL = 16 300 400
0.001 OUTPUT POWER (mW)
0.001 0 100 200 OUTPUT POWER (mW)
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5
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
Typical Operating Characteristics (continued)
(Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4366 toc19
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4366 toc20
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
VCC = 3V AV = 2V/V RL = 16
MAX4366 toc21
100 VCC = 5V AV = 2V/V RL = 32
100
100
10
10
10
THD+N (%)
THD+N (%)
1
1 f = 10kHz 0.1
THD+N (%)
1 f = 10kHz
0.1 f = 1kHz 0.01
f = 10kHz
0.1
0.01
f = 1kHz
VCC = 5V AV = 4V/V RL = 32 200 300 400
0.01 f = 1kHz 0.001 0 75 150 225 300
0.001 0 100 200 300 400 OUTPUT POWER (mW)
0.001 0 100 OUTPUT POWER (mW)
OUTPUT POWER (mW)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4366 toc22
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4366 toc23
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX4366 toc24
100
100 VCC = 3V AV = 2V/V RL = 32
100 f = 10kHz
10
10
f = 10kHz
10
THD+N (%)
THD+N (%)
1 f = 10kHz 0.1
1
THD+N (%)
1
0.1
0.1
0.01
f = 1kHz
VCC = 3V AV = 4V/V RL = 16 225 300
0.01 f = 1kHz 0.001
0.01
f = 1kHz
VCC = 3V AV = 4V/V RL = 32 150 225 300
0.001 0 75 150 OUTPUT POWER (mW)
0.001 0 75 150 225 300 0 75 OUTPUT POWER (mW) OUTPUT POWER (mW)
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4366 toc25
OUTPUT POWER vs. SUPPLY VOLTAGE
RL = 16 500 OUTPUT POWER (mW) 400 300 200 THD+N = 1% 100 0 THD+N = 10%
MAX4366 toc26
500 RL = 32 400 OUTPUT POWER (mW) THD+N = 10%
600
300
200
THD+N = 1%
100
0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V)
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
6
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330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
Typical Operating Characteristics (continued)
(Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.)
OUTPUT POWER vs. LOAD
MAX4366 toc27
OUTPUT POWER vs. LOAD
THD+N = 10% AV = 20V/V
MAX4366 toc28
450 400 350 OUTPUT POWER (mW) 300 250 200 150 100 50 0 10 100 1k VCC = 5V f = 1kHz THD+N = 1% AV = 2V/V THD+N = 10% AV = 20V/V
250
200 OUTPUT POWER (mW)
150 THD+N = 1% AV = 2V/V VCC = 3V f = 1kHz
100
50
0 10k 10 100 1k 10k LOAD RESISTANCE () LOAD RESISTANCE ()
POWER DISSIPATION vs. OUTPUT POWER
MAX4366 toc29
POWER DISSIPATION vs. OUTPUT POWER
VCC = 3V AV = 2V/V RL = 16 100
MAX4366 toc30
500 VCC = 5V AV = 2V/V POWER DISSIPATION (mW) 400 RL = 16 300
200
POWER DISSIPATION (mW)
150
200 RL = 32
100
50
RL = 32
0 0 50 100 150 200 OUTPUT POWER (mW)
0 0 20 40 60 80 100 OUTPUT POWER (mW)
POWER DISSIPATION vs. OUTPUT POWER
VCC = 5V AV = 2V/V SINGLE ENDED 150 RL = 16 100
MAX4366 toc31
GAIN AND PHASE vs. FREQUENCY
80 60 40 20 0 -20 -40 -60 -80 -100 -120 -140 -160 -180 100
MAX4366 toc32
200
GAIN
POWER DISSIPATION (mW)
GAIN (dB)/PHASE (deg)
PHASE VCC = 5V AV = 1000V/V SINGLE ENDED NO LOAD 1k 10k 100k 1M 10M 100M
50 RL = 32 0 0 10 20 30 40 50 OUTPUT POWER (mW)
FREQUENCY (Hz)
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330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
Typical Operating Characteristics (continued)
(Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.)
DIFFERENTIAL POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
-10 -20 PSRR (dB) -30 -40 -50 -60 -70 -80 10 100 1k 10k 100k 1M FREQUENCY (Hz) VCC = 5V 0 0 1 2 3 4 5 SUPPLY VOLTAGE (V) VCC = 3V
MAX4366 toc33
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4366 toc34
0
2.5
2.0 SUPPLY CURRENT (mA)
1.5
1.0
0.5
SUPPLY CURRENT vs. TEMPERATURE
MAX4366 toc35
SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
40 35 30 25 20 15 10 5
MAX4366 toc36
3.0 2.5 SUPPLY CURRENT (mA) 2.0 1.5 1.0 0.5 0 -40 -15 10 35 60 VCC = 5V VCC = 3V
45 SHUTDOWN SUPPLY CURRENT (A)
0 85 0 1 2 3 4 5 TEMPERATURE (C) SUPPLY VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE
45 40 SUPPLY CURRENT (A) 35 30 25 20 15 10 5 0 -40 -15 10 35 60 85 TEMPERATURE (C) VCC = 3V VCC = 5V
MAX4366 toc37
50
8
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330mW, Ultra-Small, Audio Power Amplifiers with Shutdown
Pin Description
PIN/BUMP SOT23/MAX/ QFN 1 2 3 4 5 6 7 8 NAME UCSP C3 C1 A3 A1 A2 B3 B1 C2 SHDN BIAS IN+ INOUT+ VCC GND OUTActive-High Shutdown. Connect SHDN to GND for normal operation. DC Bias Bypass. See BIAS Capacitor section for capacitor selection. Connect CBIAS capacitor from BIAS to GND. Noninverting Input Inverting Input Bridged Amplifier Positive Output Power Supply Ground Bridged Amplifier Negative Output FUNCTION
MAX4366/MAX4367/MAX4368
Detailed Description
The MAX4366/MAX4367/MAX4368 bridged audio power amplifiers can deliver 330mW into a 32 load, or 200mW into a 16 load, while operating from a single 5V supply. These devices consist of two high-outputcurrent op amps configured as a bridge-tied load (BTL) amplifier (see Functional Diagram). The closed-loop gain of the input op amp sets the single-ended gain of the device. Two external resistors set the gain of the MAX4366 (see Gain-Setting Resistors section). The MAX4367/MAX4368 feature internally fixed gains of 2V/V and 3V/V, respectively. The output of the first amplifier serves as the input to the second amplifier, which is configured as an inverting unity-gain follower in all three devices. This results in two outputs, identical in magnitude, but 180 out of phase.
+1 OUT+
RL
2 x OUT
-1
OUT-
Figure 1. Bridge-Tied Load Configuration
high disables the device's bias circuitry and drives OUT+, OUT-, and BIAS to GND. Connect SHDN to GND for normal operation.
BIAS
The MAX4366/MAX4367/MAX4368 feature an internally generated common-mode bias voltage of VCC/2 referenced to GND. BIAS provides both click-and-pop suppression and the DC bias level for the audio signal. BIAS is internally connected to the noninverting input of one amplifier, and should be connected to the noninverting input of the other amplifier for proper signal biasing (Typical Application Circuit). Choose the value of the bypass capacitor as described in the BIAS Capacitor section.
Applications Information
Bridge-Tied Load
The MAX4366/MAX4367/MAX4368 are designed to drive a load differentially, a configuration referred to as bridge-tied load (BTL). The BTL configuration (Figure 1) offers advantages over the single-ended configuration, where one side of the load is connected to ground. Driving the load differentially doubles the output voltage compared to a single-ended amplifier under similar conditions. The differential gain of the device is twice the closed-loop gain of the input amplifier. The effective gain of the MAX4366 is given by: A VD = 2 x RF RIN
Shutdown
The MAX4366/MAX4367/MAX4368 feature a 35A, lowpower shutdown mode that reduces quiescent current consumption and extends battery life. Pulling SHDN
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330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
The effective gains of the MAX4367 and MAX4368 are AVD = 2V/V and AVD = 3V/V respectively. Substituting 2 x VOUT(P-P) for VOUT(P-P) into the following equations yields four times the output power due to doubling of the output voltage. VRMS = VOUT(P-P) 22 In single-ended mode, the load must be capacitively coupled to the device output to block the half-supply DC voltage from the load (see Output Coupling Capacitor section). Leave the unused output floating.
Power Dissipation
Under normal operating conditions, linear power amplifiers like the MAX4366/MAX4367/MAX4368 can dissipate a significant amount of power. The maximum power dissipation for each package is given in the Absolute Maximum Ratings section under Continuous Power Dissipation or can be calculated by the following equation: PDISS(MAX) = TJ(MAX) - TA JA
2 V POUT = RMS RL
Since the differential outputs are biased at midsupply, there is no net DC voltage across the load. This eliminates the need for DC-blocking capacitors required for single-ended amplifiers. These capacitors can be large, expensive, consume board space, and degrade low-frequency performance.
where TJ(MAX) is +150C and TA is the reciprocal of the derating factor in C/W as specified in the Absolute
5 COUT RL
Single-Ended Configuration
The MAX4366/MAX4367/MAX4368 can be used as single-ended amplifiers (Figure 2). The gain of the device in single-ended mode is 1/2 the gain in BTL configuration and the output power is reduced by a factor of 4. The single-ended gains of the MAX4367 and MAX4368 are 1V/V and 1.5V/V, respectively. Set the MAX4366 gain according to the Gain-Setting Resistors section.
OUT+
MAX4367
OUT8
Figure 2. MAX4367 Single-Ended Configuration
VCC
6 VCC 50k 2 BIAS OUTCBIAS 50k 8 CLICKLESS/ POPLESS SHUTDOWN CONTROL SHDN 1
3
IN+
10k 10k OUT+ 5
CIN AUDIO INPUT
RIN
4
INMAX4366 GND 7
RF
Figure 3. MAX4366 Typical Application Circuit 10 ______________________________________________________________________________________
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
VCC
6 VCC 50k 2 BIAS OUTCBIAS 50k 8 CLICKLESS/ POPLESS SHUTDOWN CONTROL SHDN 1
3
IN+
10k 10k OUT+ 5
CIN AUDIO INPUT
4
IN-
RIN RF MAX4367 MAX4368 7
GND
MAX4367: RIN = RF = 20k MAX4368: RIN = 20k, RF = 30k PIN NUMBERS REFER TO SOT23, QFN, AND MAX PACKAGES
Figure 4. MAX4367/MAX4368 Typical Application Circuit
Maximum Ratings section. For example, JA of a MAX package is 222C/W. The increase in power delivered by the BTL configuration directly results in an increase in internal power dissipation over the single-ended configuration. If the power dissipation exceeds the maximum allowed for a given package, either reduce V CC , increase load impedance, decrease the ambient temperature, or add heat sinking to the device. Large output, supply, and ground traces improve the maximum power dissipation in the package. Thermal overload protection limits total power dissipation in the MAX4366/MAX4367/MAX4368. When the junction temperature exceeds +165C, the thermal protection circuitry disables the amplifier output stage. The amplifiers are re-enabled once the junction temperature cools by +10C. This results in a pulsing output under continuous thermal overload conditions avoiding damage to the port.
Component Selection
Gain-Setting Resistors External feedback components set the gain of the MAX4366. Resistors RF and RIN (Figure 3) set the gain of the input amplifier as follows: R A VD = 2 F RIN The gain of the device in a single-ended configuration is half the gain of the BTL case. Choose RF between 10k and 50k. The gains of the MAX4367/MAX4368 are set internally (Figure 4). Input Filter The input capacitor (CIN), in conjunction with RIN 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: -3dB = 1 2RINCIN
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11
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
Choose RIN according to the Gain-Setting Resistors section. Choose the CIN such that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the low-frequency response of the system. Other considerations when designing the input filter include the constraints of the overall system, the actual frequency band of interest and click-and-pop suppression. Although high-fidelity audio calls for a flat-gain response between 20Hz and 20kHz, portable voicereproduction devices such as cellular phones and twoway radios need only concentrate on the frequency range of the spoken human voice (typically 300Hz to 3.5kHz). In addition, speakers used in portable devices typically have a poor response below 150Hz. Taking these two factors into consideration, the input filter may not need to be designed for a 20Hz to 20kHz response, saving both board space and cost due to the use of smaller capacitors. BIAS Capacitor The BIAS bypass capacitor, CBIAS improves powersupply rejection ratio and THD+N by reducing powersupply noise at the common-mode bias node, and serves as the primary click-and-pop suppression mechanism. CBIAS is fed from an internal 25k source, and controls the rate at which the common-mode bias voltage rises at startup and falls during shutdown. For optimum click-and-pop suppression, ensure that the input capacitor (CIN) is fully charged (ten time constants) before CBIAS. The value of CBIAS for best clickand-pop suppression is given by: C R CBIAS 10 IN IN 25k In addition, a larger CBIAS value yields higher PSRR, especially in single-ended applications. Output-Coupling Capacitor The MAX4366/MAX4367/MAX4368 require output-coupling capacitors only when configured as a singleended amplifier. The output capacitor blocks the DC component of the amplifier output, preventing DC current flowing to the load. The output capacitor and the load impedance form a highpass filter with the -3dB point determined by: -3dB = 1 2RLCOUT
TIP (SIGNAL)
SLEEVE (GND)
Figure 5. Typical 2-Wire Headphone Plug
In addition to click-and-pop suppression and frequency band considerations, the load impedance is another concern when choosing COUT. Load impedance can vary, changing the -3dB point of the output filter. A lower impedance increases the corner frequency, degrading low-frequency response. Select COUT such that the worst-case load/COUT combination yields an adequate response. Clickless/Popless Operation Proper selection of AC-coupling capacitors and CBIAS achieves clickless/popless shutdown and startup. The value of CBIAS determines the rate at which the mid-rail bias voltage rises on startup and falls when entering shutdown. The size of the input capacitor also affects clickless/popless operation. On startup, CIN is charged to its quiescent DC voltage through the feedback resistor (RF) from the output. This current creates a voltage transient at the amplifier's output, which can result in an audible pop. Minimizing the size of CIN reduces this effect, improving click-and-pop suppression. Supply Bypassing Proper supply bypassing ensures low-noise, low-distortion performance. Place a 0.1F ceramic capacitor in parallel with a 10F capacitor from VCC to GND. Locate the bypass capacitors as close to the device as possible.
Headphone Applications
The MAX4366/MAX4368 can drive a mono headphone when configured as a single-ended amplifier. Typical 2wire headphone plugs consist of a tip and sleeve. The tip is the signal carrier while the sleeve is the ground connection (Figure 5). Figure 6 shows the device configured to drive headphones. OUT+ is connected to the tip, delivering the signal to the headphone, while OUTremains unconnected.
As with the input capacitor, choose the output capacitor (COUT) such that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the lowfrequency response of the system.
12
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330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
OUT+ OUT+ 5 COUT HEADPHONE JACK
MAX4366 MAX4367 MAX4368
MAX4366 MAX4367 MAX4368
COUT
EARBUD SPEAKER JACK
OUT-
OUT-
8
INTERNAL LOUDSPEAKER
Figure 6. MAX4367 Headphone Application Circuit
Figure 7. Headset with Internal Speaker Application Circuit
tion passes the audio signal unattenuated. Setting the wiper to the lowest position fully attenuates the input. Use the 100k version of the MAX5160.
AUDIO INPUT 3H
MAX5160
W5 4 CIN IN- MAX4367
OUT+
5
Layout Considerations
Good layout improves performance by decreasing the amount of stray capacitance and noise at the amplifier's inputs and outputs. Decrease stray capacitance by minimizing PC board trace lengths, using surfacemount components and placing external components as close to the device as possible.
6L
MAX4368
OUT-
8
UCSP Considerations
Figure 8. MAX4367/MAX5160 Volume Control Circuit
For general UCSP information and PC layout considerations, please refer to the Maxim Application Note: UCSP-A Wafer-Level Chip-Scale Package.
Wireless-Phone Headset Application Many wireless telephones feature an earbud speaker/inline microphone combination for hands-free use. One common solution is to use a BTL amplifier that drives the internal speaker and an earplug jack that mutes the internal speaker by physically disconnecting OUT- when a headset is plugged in (Figure 7). The headset is driven single-endedly, requiring an output-coupling capacitor, COUT, and resulting in a 4x reduction in output power.
Adding Volume Control
The addition of a digital potentiometer provides simple volume control. Figure 8 shows the MAX4367/MAX4368 with the MAX5160 digital potentiometer used as an input attenuator. Connect the high terminal of the MAX5160 to the audio input, the low terminal to ground and the wiper to CIN. Setting the wiper to the top posi-
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13
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
Pin Configurations (continued)
TOP VIEW
Ordering Information (continued)
PART TEMP RANGE PIN/BUMPPACKAGE 8 UCSP-8 8 SOT23-8 8 MAX 8 Thin QFN-EP* 8 UCSP-8 8 SOT23-8 8 MAX 8 Thin QFN-EP* TOP MARK AAL AAIP -- AAB AAM AAIQ -- AAA
MAX4367EBL-T -40C to +85C MAX4367EKA-T -40C to +85C
SHDN 1 BIAS 2 IN+ 3 8 7 OUTGND VCC OUT+
MAX4367EUA MAX4367ETA
-40C to +85C -40C to +85C
MAX4366 MAX4367 MAX4368
6 5
MAX4368EBL-T -40C to +85C MAX4368EKA-T -40C to +85C MAX4368EUA MAX4368ETA -40C to +85C -40C to +85C
IN- 4
SOT23/MAX/THIN QFN
*EP = Exposed paddle.
Selector Guide
PART MAX4366 MAX4367 MAX4368 GAIN External 2V/V 3V/V
14
______________________________________________________________________________________
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown
Functional Diagrams
VCC VCC 50k 50k BIAS 50k OUTSHDN CLICKLESS/ POPLESS SHUTDOWN CONTROL 50k OUT-
MAX4366/MAX4367/MAX4368
MAX4366
BIAS
MAX4367 MAX4368
SHDN
CLICKLESS/ POPLESS SHUTDOWN CONTROL
10k 10k IN+ 10k OUT+ OUT+ IN20k RF* GND *RF = 30k (MAX4368) RF = 20k (MAX4367) GND 10k
IN+
IN-
Chip Information
TRANSISTOR COUNT: 669 PROCESS: Bipolar
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15
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
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.)
SOT23, 8L .EPS
REV.
SEE DETAIL "A" b
C L
e
SYMBOL A A1 A2 b C D E E1 L L2 e e1
MIN 0.90 0.00 0.90 0.28 0.09 2.80 2.60 1.50 0.30
MAX 1.45 0.15 1.30 0.45 0.20 3.00 3.00 1.75 0.60 0.25 BSC.
C L
E
C L
E1
PIN 1 I.D. DOT (SEE NOTE 6) e1 D C
C L
0
0.65 BSC. 1.95 REF. 0 8
L2 A A2 A1
SEATING PLANE C
GAUGE PLANE
L
0
NOTE:
1. ALL DIMENSIONS ARE IN MILLIMETERS. 2. FOOT LENGTH MEASURED FROM LEAD TIP TO UPPER RADIUS OF HEEL OF THE LEAD PARALLEL TO SEATING PLANE C. 3. PACKAGE OUTLINE EXCLUSIVE OF MOLD FLASH & METAL BURR. 4. PACKAGE OUTLINE INCLUSIVE OF SOLDER PLATING. 5. COPLANARITY 4 MILS. MAX. 6. PIN 1 I.D. DOT IS 0.3 MM y MIN. LOCATED ABOVE PIN 1. 7. SOLDER THICKNESS MEASURED AT FLAT SECTION OF LEAD BETWEEN 0.08mm AND 0.15mm FROM LEAD TIP. 8. MEETS JEDEC MO178.
PROPRIETARY INFORMATION TITLE:
DETAIL "A"
PACKAGE OUTLINE, SOT-23, 8L BODY
APPROVAL DOCUMENT CONTROL NO.
21-0078
1 1
D
4X S
8
8
INCHES DIM A A1 A2 b MIN 0.002 0.030 MAX 0.043 0.006 0.037
MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95
y 0.500.1
E
H
0.60.1
c D e E H L
1
1
0.60.1
S
D
BOTTOM VIEW
0.010 0.014 0.005 0.007 0.116 0.120 0.0256 BSC 0.116 0.120 0.188 0.198 0.016 0.026 6 0 0.0207 BSC
0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0 6 0.5250 BSC
TOP VIEW
A2
A1
A
c e b L
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL DOCUMENT CONTROL NO. REV.
21-0036
1 1
J
16
______________________________________________________________________________________
8LUMAXD.EPS
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
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.)
6, 8, &10L, QFN THIN.EPS
PACKAGE OUTLINE, 6, 8 & 10L, QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
21-0137
C
COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40
0.25 MIN 0.20 REF.
PACKAGE VARIATIONS PKG. CODE T633-1 T833-1 T1033-1 N 6 8 10 D2 1.500.10 1.500.10 1.500.10 E2 2.300.10 2.300.10 2.300.10 e 0.95 BSC 0.65 BSC 0.50 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEC MO229 / WEED-3 b 0.400.05 0.300.05 0.250.05 [(N/2)-1] x e 1.90 REF 1.95 REF 2.00 REF
PACKAGE OUTLINE, 6, 8 & 10L, QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
21-0137
C
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17
330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368
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.)
9LUCSP, 3x3.EPS
Note: Bump B2 is not present.
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.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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