19-2338; Rev 5; 6/08 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown 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 TDFN and 8-bump UCSPTM chip-scale packages. Features Drives 330mW into 32 (200mW into 16) 0.02% THD+N at 1kHz (120mW into 32) Internal Bridged Configuration No Output-Coupling Capacitors 2.3V to 5.5V Single-Supply Operation 2mA Supply Current Low-Power Shutdown Mode Clickless Power-Up and Shutdown Thermal Overload Protection Available in TDFN and UCSP Packages Ordering Information Applications Cellular Phones Two-Way Radios PDAs Headphones Headsets General-Purpose Audio PART TEMP RANGE PIN/BUMPPACKAGE TOP MARK MAX4366EBL-T -40C to +85C 8 UCSP AAK MAX4366ETA+T -40C to +85C 8 TDFN-EP* +AFZ *EP = Exposed pad. +Denotes a lead-free package. Ordering Information continued at end of data sheet. Selector Guide and Functional Diagrams appear at end of data sheet. Typical Operating Circuit Pin Configurations TOP VIEW (BUMP SIDE DOWN) VCC 1 2 3 IN- OUT+ IN+ VCC A CLICKLESS/POPLESS SHUTDOWNCONTROL SHDN BIAS OUTB GND MAX4366 MAX4367 MAX4368 VCC IN+ C BIAS OUT- SHDN UCSP AUDIO INPUT OUT+ IN- MAX4367 MAX4368 GND Pin Configurations continued at end of data sheet. UCSP is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX4366/MAX4367/MAX4368 General Description MAX4366/MAX4367/MAX4368 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown ABSOLUTE MAXIMUM RATINGS 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 VCC to GND ..............................................................-0.3V to +6V IN+, IN-, BIAS, SHDN to GND....................-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 TDFN (derate 24.4mWC above +70C) ...........1951mW 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 SYMBOL CONDITIONS VCC Inferred from PSRR test ICC (Note 4) SHDN = VCC ISHDN VIH MIN VBIAS VOS AV Input Common-Mode Range VCM Differential Input Resistance RIN(DIFF) Input Resistance VCC/2 - 5% (Note 5) MAX4367, IN- = open (Note 6) mA A 5 15 5 15 7.5 15 100 V mV dB V/V VCC 1.0 0.3 V MAX4366, VIN+ - VIN- = 10mV 500 k VIN- = 0V to VCC (MAX4367/MAX4368) 20 k TA = +25C 70 TA = TMIN to TMAX 66 Common-Mode Rejection Ratio CMRR 0V VCM VCC - 1.0V (MAX4366) (Note 7) 2.7V VCC 5.5V, 0.6V VOUT VCC - 0.6V f = 1kHz, THD+N <1% (Note 8) 80 80 87 dB dB 125 mA 2.3V VCC 2.7V, 0.6V VOUT VCC - 0.6V PO 5 3 VCC = 2.3V to 5.5V IOUT VCC/2 + 5% 2 V nA VCC/2 MAX4368 (internally set) PSRR 2 4.3 100 MAX4367 (internally set) Power-Supply Rejection Ratio Output Power 2 35 -400 MAX4366 (open loop) Output Source/Sink Current V 0.8 MAX4368, IN- = open Differential Voltage Gain UNITS 5.5 1.8 MAX4366, RIN = Output Offset Voltage MAX VIL SHDN Input Bias Current Common-Mode Bias Voltage TYP 2.3 115 RL = 16 60 200 RL = 32 120 330 mW _______________________________________________________________________________________ 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown (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 SYMBOL THD+N Noise CONDITIONS AV = -2V/V, f = 1kHz (MAX4366) (Notes 9 and 10) ISC TYP PO = 60mW, RL = 16 0.04 PO = 120mW, RL = 32 0.02 MAX UNITS % f = 10kHz, referred to input Short-Circuit Current MIN 20 To VCC 185 To GND 215 0.15 nV/Hz mA Thermal Shutdown Threshold 165 C Thermal Shutdown Hysteresis 10 C tPU 60 ms tSHDN 20 ms tENABLE 60 ms Power-Up Time Shutdown Time Enable Time from Shutdown 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. _______________________________________________________________________________________ 3 MAX4366/MAX4367/MAX4368 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 1 VCC = 5V AV = 3V/V RL = 16 POUT = 10mW 1 POUT = 10mW POUT = 10mW 0.1 THD+N (%) POUT = 25mW THD+N (%) 0.1 THD+N (%) 0.1 0.01 POUT = 25mW 0.01 VCC = 5V AV = 4V/V RL = 16 0.001 0.001 100 POUT = 25mW POUT = 60mW 0.01 POUT = 60mW POUT = 60mW 10 1k 10k 0.001 10 100k 100 1k 10k 100k 10 100 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY VCC = 5V AV = 2V/V RL = 32 POUT = 10mW 0.1 0.1 THD+N (%) POUT = 25mW THD+N (%) VCC = 5V AV = 3V/V RL = 32 POUT = 60mW 0.01 THD+N (%) 0.1 1 MAX4366 toc05 MAX4366 toc04 1 POUT = 50mW 0.01 VCC = 5V AV = 20V/V RL = 16 POUT = 75mW POUT = 120mW POUT = 120mW 0.001 10 100 1k 10k POUT = 50mW 0.01 POUT = 75mW 0.001 100k MAX4366 toc06 FREQUENCY (Hz) 1 0.001 10 100 1k 10k 100k 10 100 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY POUT = 50mW POUT = 50mW VCC = 3V AV = 2V/V RL = 16 0.1 0.1 POUT = 75mW 0.01 POUT = 120mW POUT = 10mW THD+N (%) THD+N (%) 0.1 1 MAX4366 toc08 1 MAX4366 toc07 VCC = 5V AV = 4V/V RL = 32 POUT = 75mW 0.01 POUT = 25mW 0.01 POUT = 120mW POUT = 60mW VCC = 5V AV = 20V/V RL = 32 0.001 0.001 10 100 1k FREQUENCY (Hz) 10k 100k MAX4366 toc09 FREQUENCY (Hz) 1 4 MAX4366 toc03 VCC = 5V AV = 2V/V RL = 16 MAX4366 toc01 1 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX4366 toc02 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY THD+N (%) MAX4366/MAX4367/MAX4368 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown 0.001 10 100 1k FREQUENCY (Hz) 10k 100k 10 100 1k FREQUENCY (Hz) _______________________________________________________________________________________ 10k 100k 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown POUT = 25mW 0.01 MAX4366 toc12 1 POUT = 60mW POUT = 25mW 0.1 POUT = 10mW THD+N (%) THD+N (%) THD+N (%) POUT = 10mW 0.1 POUT = 10mW 0.1 1 MAX4366 toc11 VCC = 3V AV = 3V/V RL = 16 MAX4366 toc10 1 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY POUT = 60mW POUT = 25mW 0.01 0.01 POUT = 60mW VCC = 3V AV = 20V/V RL = 16 VCC = 3V AV = 4V/V RL = 16 0.001 0.001 0.001 10 100 1k 10k 10 100k 100 1k 10k 10 100k 100 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY VCC = 3V AV = 3V/V RL = 32 0.1 POUT = 25mW 0.01 0.01 0.01 0.001 0.001 0.001 100 POUT = 50mW POUT = 50mW POUT = 50mW 10 POUT = 25mW THD+N (%) THD+N (%) THD+N (%) POUT = 25mW VCC = 3V AV = 4V/V RL = 32 POUT = 10mW POUT = 10mW 0.1 0.1 1 MAX4366 toc15 1 MAX4366 toc14 POUT = 10mW VCC = 3V AV = 2V/V RL = 32 MAX4366 toc13 1 1k 10k 10 100k 100 1k 10k 10 100k 100 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER THD+N (%) 0.1 POUT = 50mW f = 10kHz 1 f = 1kHz 0.1 MAX4366 toc18 10 10 THD+N (%) POUT = 25mW 100 MAX4366 toc17 POUT = 10mW THD+N (%) 100 MAX4366 toc16 1 1 f = 10kHz 0.1 0.01 VCC = 5V AV = 2V/V RL = 16 0.01 VCC = 3V AV = 20V/V RL = 32 0.01 0.001 0.001 10 100 1k FREQUENCY (Hz) 10k 100k VCC = 5V AV = 4V/V RL = 16 f = 1kHz 0.001 0 100 200 300 OUTPUT POWER (mW) 400 0 100 200 300 400 OUTPUT POWER (mW) _______________________________________________________________________________________ 5 MAX4366/MAX4367/MAX4368 Typical Operating Characteristics (continued) (Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.) Typical Operating Characteristics (continued) (Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.) f = 10kHz f = 1kHz 0.01 1 f = 10kHz 0.1 0.01 0.001 VCC = 5V AV = 4V/V RL = 32 f = 1kHz 100 200 400 300 VCC = 3V AV = 2V/V RL = 16 10 1 f = 10kHz 0.1 0.01 f = 1kHz 0.001 0.001 0 0 100 200 75 0 400 300 150 225 300 OUTPUT POWER (mW) OUTPUT POWER (mW) OUTPUT POWER (mW) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER f = 10kHz 0.1 VCC = 3V AV = 4V/V RL = 16 f = 10kHz 1 0.1 150 300 225 75 150 0 300 225 MAX4366 toc24 75 OUTPUT POWER vs. SUPPLY VOLTAGE RL = 16 500 OUTPUT POWER (mW) THD+N = 10% 300 THD+N = 1% 200 225 OUTPUT POWER vs. SUPPLY VOLTAGE 600 MAX4366 toc25 RL = 32 150 OUTPUT POWER (mW) OUTPUT POWER (mW) 500 OUTPUT POWER (mW) VCC = 3V AV = 4V/V RL = 32 f = 1kHz 0.001 0 OUTPUT POWER (mW) 400 0.1 f = 1kHz 0.001 75 1 0.01 0.01 0.001 0 f = 10kHz 10 MAX4366 toc26 f = 1kHz VCC = 3V AV = 2V/V RL = 32 THD+N (%) 1 0.01 10 THD+N (%) 10 100 MAX4366 toc23 100 MAX4366 toc22 100 400 THD+N = 10% 300 200 THD+N = 1% 100 100 0 0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 6 100 THD+N (%) 1 0.1 10 THD+N (%) THD+N (%) 10 100 MAX4366 toc20 VCC = 5V AV = 2V/V RL = 32 MAX4366 toc19 100 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER MAX4366 toc21 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER THD+N (%) MAX4366/MAX4367/MAX4368 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown 5.0 5.5 2.5 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5.5 300 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown OUTPUT POWER vs. LOAD OUTPUT POWER vs. LOAD 250 THD+N = 1% AV = 2V/V 200 150 VCC = 5V f = 1kHz 100 50 150 THD+N = 1% AV = 2V/V 100 VCC = 3V f = 1kHz 50 0 0 100 10 10k 1k 100 MAX4366 toc29 200 400 POWER DISSIPATION (mW) POWER DISSIPATION (mW) VCC = 5V AV = 2V/V RL = 16 300 200 RL = 32 VCC = 3V AV = 2V/V 150 RL = 16 100 50 RL = 32 0 0 0 50 100 150 0 200 20 POWER DISSIPATION vs. OUTPUT POWER VCC = 5V AV = 2V/V SINGLE ENDED GAIN (dB)/PHASE (deg) 150 RL = 16 100 50 RL = 32 0 10 20 30 OUTPUT POWER (mW) 60 80 100 GAIN AND PHASE vs. FREQUENCY MAX4366 toc31 200 0 40 OUTPUT POWER (mW) OUTPUT POWER (mW) POWER DISSIPATION (mW) 10k POWER DISSIPATION vs. OUTPUT POWER POWER DISSIPATION vs. OUTPUT POWER 500 100 1k LOAD RESISTANCE () LOAD RESISTANCE () MAX4366 toc30 10 40 50 80 60 40 20 0 -20 -40 -60 -80 -100 -120 -140 -160 -180 MAX4366 toc32 OUTPUT POWER (mW) 300 THD+N = 10% AV = 20V/V 200 OUTPUT POWER (mW) THD+N = 10% AV = 20V/V 350 MAX4366 toc28 400 250 MAX4366 toc27 450 GAIN PHASE VCC = 5V AV = 1000V/V SINGLE ENDED NO LOAD 100 1k 10k 100k 1M 10M 100M FREQUENCY (Hz) _______________________________________________________________________________________ 7 MAX4366/MAX4367/MAX4368 Typical Operating Characteristics (continued) (Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.) Typical Operating Characteristics (continued) (Bridge-Tied Load, THD+N Bandwidth = 22Hz to 22kHz, CBIAS = 1F.) DIFFERENTIAL POWER-SUPPLY REJECTION RATIO vs. FREQUENCY SUPPLY CURRENT vs. SUPPLY VOLTAGE -10 2.0 SUPPLY CURRENT (mA) -30 VCC = 3V -50 -60 1.0 0.5 VCC = 5V -70 1.5 -80 0 10 100 1k 10k 100k 1M 0 1 2 3 4 FREQUENCY (Hz) SUPPLY VOLTAGE (V) SUPPLY CURRENT vs. TEMPERATURE SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE 45 2.5 2.0 SHUTDOWN SUPPLY CURRENT (A) MAX4366 toc35 3.0 VCC = 5V 1.5 5 VCC = 3V 1.0 0.5 MAX4366 toc36 PSRR (dB) -20 -40 MAX4366 toc34 2.5 MAX4366 toc33 0 SUPPLY CURRENT (mA) 40 35 30 25 20 15 10 5 0 0 -40 -15 10 35 0 85 60 1 2 3 4 5 SUPPLY VOLTAGE (V) TEMPERATURE (C) SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE MAX4366 toc37 50 45 40 SUPPLY CURRENT (A) MAX4366/MAX4367/MAX4368 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown VCC = 5V 35 30 25 VCC = 3V 20 15 10 5 0 -40 -15 10 35 60 85 TEMPERATURE (C) 8 _______________________________________________________________________________________ 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown PIN/BUMP NAME FUNCTION TDFN UCSP 1 C3 SHDN Active-High Shutdown. Connect SHDN to GND for normal operation. 2 C1 BIAS DC Bias Bypass. See BIAS Capacitor section for capacitor selection. Connect CBIAS capacitor from BIAS to GND. 3 A3 IN+ Noninverting Input 4 A1 IN- Inverting Input 5 A2 OUT+ 6 B3 VCC Power Supply 7 B1 GND Ground 8 C2 OUT- EP -- EP Bridged Amplifier Positive Output Bridged Amplifier Negative Output Exposed Paddle. Connect exposed pad to GND. 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. 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. Shutdown The MAX4366/MAX4367/MAX4368 feature a 35A, lowpower shutdown mode that reduces quiescent current consumption and extends battery life. Pulling SHDN OUT+ +1 RL 2 x OUT OUT- -1 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. 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 _______________________________________________________________________________________ 9 MAX4366/MAX4367/MAX4368 Pin Description MAX4366/MAX4367/MAX4368 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown 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. VOUT(P-P) VRMS = 2 2 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. 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 where TJ(MAX) is +150C and TA is the reciprocal of the derating factor in C/W as specified in the Absolute 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+ 5 COUT MAX4367 OUT- 8 Figure 2. MAX4367 Single-Ended Configuration VCC 6 CLICKLESS/ POPLESS SHUTDOWN CONTROL VCC 50k 2 SHDN 1 OUT- 8 BIAS CBIAS 50k 3 IN+ 10k 10k OUT+ 5 CIN RIN AUDIO INPUT 4 INMAX4366 GND 7 RF Figure 3. MAX4366 Typical Application Circuit 10 ______________________________________________________________________________________ RL 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown 6 CLICKLESS/ POPLESS SHUTDOWN CONTROL VCC 50k 2 1 OUT- 8 OUT+ 5 BIAS CBIAS 50k 3 CIN AUDIO INPUT SHDN 4 10k IN+ IN- 10k RIN RF MAX4367 MAX4368 GND 7 MAX4367: RIN = RF = 20k MAX4368: RIN = 20k, RF = 30k PIN NUMBERS REFER TO TDFN PACKAGE. Figure 4. MAX4367/MAX4368 Typical Application Circuit Maximum Ratings section. For example, JA of a TDFN package is 41C/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 part. 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: f-3dB = 1 2RINCIN ______________________________________________________________________________________ 11 MAX4366/MAX4367/MAX4368 VCC MAX4366/MAX4367/MAX4368 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown 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: f-3dB = 1 2RLCOUT 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 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. ______________________________________________________________________________________ 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown OUT+ MAX4366 MAX4367 MAX4368 5 HEADPHONE JACK COUT OUT- MAX4366 MAX4367 MAX4368 COUT EARBUD SPEAKER JACK OUT- INTERNAL LOUDSPEAKER 8 Figure 6. MAX4367 Headphone Application Circuit Figure 7. Headset with Internal Speaker Application Circuit Adding Volume Control AUDIO INPUT 3 H MAX5160 OUT+ W 5 6 L 4 CIN 5 IN- MAX4367 MAX4368 OUT- 8 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 position passes the audio signal unattenuated. Setting the wiper to the lowest position fully attenuates the input. Use the 100k version of the MAX5160. Layout Considerations Figure 8. MAX4367/MAX5160 Volume Control Circuit 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. 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. UCSP Considerations For general UCSP information and PC layout considerations, please refer to the Maxim Application Note: UCSP-A Wafer-Level Chip-Scale Package. ______________________________________________________________________________________ 13 MAX4366/MAX4367/MAX4368 OUT+ 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown MAX4366/MAX4367/MAX4368 Pin Configurations (continued) TOP VIEW GND VCC OUT+ MAX4367EBL-T -40C to +85C 8 7 6 5 MAX4367ETA+T -40C to +85C PIN/BUMPPACKAGE 8 UCSP 8 TDFN-EP* MAX4368EBL-T -40C to +85C 8 UCSP MAX4368ETA+T -40C to +85C 8 TDFN-EP* TOP MARK AAL +AGA AAM +AGB *EP = Exposed paddle. +Denotes lead-free package. 1 2 3 4 SHDN BIAS IN+ IN- *EXPOSED PAD. CONNECT TO GND. + TEMP RANGE OUT- PART MAX4366 MAX4367 MAX4368 TDFN (3mm x 3mm x 0.8mm) 14 Ordering Information (continued) Selector Guide PART GAIN MAX4366 External MAX4367 2V/V MAX4368 3V/V ______________________________________________________________________________________ 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown VCC VCC 50k 50k MAX4366 MAX4367 MAX4368 BIAS BIAS SHDN CLICKLESS/ POPLESS SHUTDOWN CONTROL OUT- 50k 10k 10k IN+ SHDN OUT- 50k CLICKLESS/ POPLESS SHUTDOWN CONTROL IN+ 10k 10k OUT+ OUT+ IN- IN- 20k R F* GND *RF = 30k (MAX4368) RF = 20k (MAX4367) Package Information Chip Information TRANSISTOR COUNT: 669 PROCESS: BiPOLAR GND For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 8 TDFN T833-2 21-0137 8 UCSP B9-2 21-0093 ______________________________________________________________________________________ 15 MAX4366/MAX4367/MAX4368 Functional Diagrams MAX4366/MAX4367/MAX4368 330mW, Ultra-Small, Audio Power Amplifiers with Shutdown Revision History REVISION NUMBER REVISION DATE 5 6/08 DESCRIPTION Removed SOT23 and MAX packages PAGES CHANGED 1, 2, 9, 11, 14 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 ____________________ 16 (c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.