MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown General Description Features The MAX4364/MAX4365 bridged outputs eliminate the need for output-coupling capacitors, minimizing external component count. The MAX4364/MAX4365 also include internal DC bias generation, clickless operation, shortcircuit and thermal-overload protection. Both devices are unity-gain stable, with the gain set by two external resistors. Ordering Information 1.4W into 8 Load (MAX4364) 1W into 8 Load (MAX4365) 0.04% THD+N at 1kHz 68dB PSRR at 217Hz 2.7V to 5.5V Single-Supply Operation 5mA Supply Current Low-Power, 10nA Shutdown Mode Pin Compatible with the LM4861/LM4862/LM4864 (MAX4364) Clickless Power-Up and Shutdown Thermal-Overload and Short-Circuit Protection Available in TDFN, MAX, and SO Packages The MAX4364/MAX4365 are bridged audio power amplifiers intended for portable audio devices with internal speakers. The MAX4364 is capable of delivering 1.4W from a single 5V supply and 500mW from a single 3V supply into an 8 load. The MAX4365 is capable of delivering 1W from a single 5V supply and 450mW from a single 3V supply into an 8 load. The MAX4364/MAX4365 feature 0.04% THD+N at 1kHz, 68dB PSRR at 217Hz, and only 10nA of supply current in shutdown mode. The MAX4364 is available in a small 8-pin SO package. The MAX4365 is available in tiny 8-pin TDFN (3mm x 3mm x 0.8mm) and MAX(R) packages. PART Applications Cellular Phones PDAs Two-Way Radios General-Purpose Audio TEMP RANGE PIN-PACKAGE MAX4364ESA/V+T -40C to +85C 8 SO -- MAX4365EUA+ -40C to +85C 8 MAX -- MAX4365ETA+ -40C to +85C 8 TDFN-EP* *EP = Exposed pad. +Denotes a lead(Pb)-free/RoHS-compliant package. /V denotes an automotive qualified part. T = Tape and reel. Pin Configurations appear at end of data sheet. Typical Application Circuit/Functional Diagram VCC 6 VCC 50k CLICKLESS/POPLESS SHDN 1 SHUTDOWN CONTROL 2 BIAS OUT- 8 CBIAS 50k 10k 3 IN+ AUDIO INPUT CIN 10k OUT+ 5 RIN 4 IN- MAX4364 RF MAX is a registered trademark of Maxim Integrated Products, Inc. 19-2387; Rev 5; 6/17 TOP MARK GND 7 ACD MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Absolute Maximum Ratings VCC, OUT_ to GND..................................................-0.3V to +6V IN+, IN-, BIAS, SHDN to GND.................. -0.3V to (VCC + 0.3V) Output Short Circuit (OUT+ to OUT-) (Note 1)..........Continuous Continuous Power Dissipation (TA = +70C) 8-Pin MAX (derate 4.8mW/C above +70C).............388mW 8-Pin TDFN (derate 24.4mW/C above +70C).........1951mW 8-Pin SO (derate 7.8mW/C above +70C)..................623mW Junction Temperature.......................................................+150C Operating Temperature Range............................ -40C to +85C Storage Temperature Range............................. -65C to +150C Lead Temperature (soldering, 10s).................................. +300C Soldering Temperature (reflow) .......................................+260C Note 1: Continuous power dissipation must also be observed. 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. Package Thermal Characteristics (Note 2) MAX Junction-to-Ambient Thermal Resistance (JA)......206.3C/W Junction-to-Case Thermal Resistance (JC)................42C/W TDFN Junction-to-Ambient Thermal Resistance (JA)...........41C/W Junction-to-Case Thermal Resistance (JC)..................8C/W SO Junction-to-Ambient Thermal Resistance (JA)......128.4C/W Junction-to-Case Thermal Resistance (JC)................36C/W Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Electrical Characteristics--5V (VCC = 5V, RL = , CBIAS = 1F to GND, VSHDN = VGND, TA = +25C, unless otherwise noted.) (Note 3) PARAMETER Supply Voltage Range SYMBOL VCC CONDITIONS Inferred from PSRR test MIN 2.7 MAX4364 Supply Current ICC (Note 4) TYP 7 MAX4364, TA = TMIN to TMAX ISHDN VIH SHDN Threshold VIL Common-Mode Bias Voltage Output Offset Voltage Power-Supply Rejection Ratio Output Power www.maximintegrated.com VBIAS VOS PSRR POUT UNITS 5.5 V 13 17 MAX4365 5 MAX4365, TA = TMIN to TMAX Shutdown Supply Current MAX 8 11 VSHDN = VCC 0.01 TA = +25C VCC x 0.7 TA = -40C to +85C (Note 5) VCC x 0.7 4 TA = +25C VCC x 0.3 TA = -40C to +85C (Note 5) VCC x 0.3 (Note 6) mA A V VCC/2 5% VCC/2 VCC/2 + 5% V 1 10 mV 55 75 IN- = OUT+, IN+ = BIAS (Note 7) VCC = 2.7V to 5.5V DC VRIPPLE = 200mVP-P, RL = 8 217Hz 68 1kHz 58 RL = 8, THD+N = 1%, fIN = 1kHz (Note 8) MAX4364 1200 1400 MAX4365 800 1000 dB mW Maxim Integrated 2 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Electrical Characteristics--5V (continued) (VCC = 5V, RL = , CBIAS = 1F to GND, VSHDN = VGND, TA = +25C, unless otherwise noted.) (Note 3) PARAMETER Total Harmonic Distortion Plus Noise SYMBOL THD+N Noise Short-Circuit Current ISC CONDITIONS AV = -2V/V, RL = 8, fIN = 1kHz (Notes 5, 9) MIN TYP MAX4364, POUT = 1W 0.04 MAX4365, POUT = 750mW 0.1 MAX UNITS % fIN = 10kHz, BW = 22Hz to 22kHz 12 VRMS OUT+ to OUT- (Note 10) 600 mA Thermal Shutdown Threshold 160 oC Thermal Shutdown Hysteresis 15 oC Power-Up Time tPU Shutdown Time tSHDN Enable Time from Shutdown tENABLE TA = +25C 50 CBIAS = 0.22F, TA = -40C to +85C (Note 5) 14 35 ms 10 s TA = +25C 50 CBIAS = 0.22F, TA = -40C to +85C (Note 5) 12 35 TYP MAX ms Electrical Characteristics--3V (VCC = 3V, RL = , CBIAS = 1F to GND, VSHDN = VGND, TA = +25C, unless otherwise noted.) (Note 3) PARAMETER Supply Current SYMBOL ICC CONDITIONS (Note 4) Shutdown Supply Current ISHDN VSHDN = VCC Output Power POUT RL = 8, THD+N = 1%, fIN = 1kHz (Note 8) Total Harmonic Distortion Plus Noise THD + N MIN MAX4364 6 MAX4365 4.5 UNITS mA 10 MAX4364 400 500 MAX4365 350 450 MAX4364, AV = -2V/V, RL = 8, POUT = 400mW fIN = 1kHz (Notes 5, 9) MAX4365, POUT = 400mW nA mW 0.05 % 0.08 Note 3: Note 4: Note Note Note Note Note Note All specifications are 100% tested at TA = +25C. 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. 5: Guaranteed by design, not production tested. 6: Common-mode bias voltage is the voltage on BIAS and is nominally VCC/2. 7: Maximum differential-output offset voltage is tested in a unity-gain configuration. VOS = VOUT+ - VOUT-. 8: Output power is specified by a combination of a functional output-current test, and characterization analysis. 9: Measurement bandwidth for THD+N is 22Hz to 22kHz. 10: Extended short-circuit conditions result in a pulsed output. www.maximintegrated.com Maxim Integrated 3 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Typical Operating Characteristics (VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.) THD+N (%) 1 0.25W 0.1 0.25W 1k 10k 100 100 1k 10k MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY VCC = 3V AV = 4V/V RL = 8 100 1k VCC = 3V AV = 20V/V RL = 8 THD+N (%) 1 0.25W 0.1 0 10 MAX4364 toc05 10 0.25W 1 0.25W 0.1 0.4W 0.4W 0.01 10k 0 100 1k 0.01 10k 0 100 1k 10k FREQUENCY (Hz) FREQUENCY (Hz) MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 20kHz 20Hz 0.1 1kHz 0 40 20kHz 1 20Hz 0.1 1kHz 0.01 200 520 1000 OUTPUT POWER (mW) www.maximintegrated.com 1650 2450 0.001 0 40 100 MAX4364 toc08 10 VCC = 5V AV = 4V/V RL = 8 200 10 THD+N (%) 1 0.01 100 MAX4364 toc07 VCC = 5V AV = 2V/V RL = 8 1000 OUTPUT POWER (mW) 1650 2450 VCC = 3V AV = 2V/V RL = 8 1 20kHz 0.1 0.01 520 MAX4364 toc09 FREQUENCY (Hz) THD+N (%) THD+N (%) 0 MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 0.1 0.001 0.01 10k MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 0.4W 10 1k FREQUENCY (Hz) THD+N (%) THD+N (%) 0 FREQUENCY (Hz) 1 100 0.5W 1W FREQUENCY (Hz) VCC = 3V AV = 2V/V RL = 8 0.01 0.25W 1W 0.01 MAX4364 toc04 10 100 1 0.5W 1W 0 VCC = 5V AV = 20V/V RL = 8 0.1 0.5W 0.01 10 MAX4364 toc06 0.1 1 MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX4364 toc03 VCC = 5V AV = 4V/V RL = 8 THD+N (%) VCC = 5V AV = 2V/V RL = 8 THD+N (%) 10 MAX4364 toc01 10 MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX4364 toc02 MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 0.001 1kHz 0 20 20Hz 190 525 1000 1700 2500 OUTPUT POWER (mW) Maxim Integrated 4 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Typical Operating Characteristics (continued) (VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.) 0.1 1kHz 0.01 200 520 1000 1650 MAX4364 toc12 1800 10% THD+N 1200 4.8 0 5.5 1% THD+N 0 10 20 40 30 50 MAX4364 POWER DISSIPATION vs. OUTPUT POWER MAX4364 POWER DISSIPATION vs. OUTPUT POWER 10% THD+N 400 700 630 10 490 420 350 280 210 VCC = 5V fIN = 1kHz RL = 8 140 70 1% THD+N 0 560 20 40 30 0 50 300 0 600 900 1200 300 270 POWER DISSIPATION (mW) VCC = 3V fIN = 1kHz MAX4364 toc15 MAX4364 OUTPUT POWER vs. LOAD RESISTANCE MAX4364 toc14 LOAD RESISTANCE () 200 240 210 180 150 120 90 VCC = 3V fIN = 1kHz RL = 8 60 30 0 1500 0 100 200 400 300 LOAD RESISTANCE () OUTPUT POWER (mW) OUTPUT POWER (mW) MAX4364 SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX4364 SUPPLY CURRENT vs. TEMPERATURE MAX4364 SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT (mA) 8.0 7.5 7.0 VCC = 5V 9 8 7 6 6.5 2.7 3.4 4.1 4.8 SUPPLY VOLTAGE (V) www.maximintegrated.com 5.5 5 12 500 MAX4364 toc18 10 MAX4364 toc16 8.5 SUPPLY CURRENT (mA) 4.1 2400 SUPPLY VOLTAGE (V) 600 6.0 3.4 2.7 VCC = 5V fIN = 1kHz 600 1% THD+N 10 SUPPLY CURRENT (nA) OUTPUT POWER (mW) 2440 800 9.0 1000 MAX4364 OUTPUT POWER vs. LOAD RESISTANCE OUTPUT POWER (mW) 1000 0 10% THD+N 1500 0 3000 MAX4364 toc17 1200 0 40 2000 500 20Hz POWER DISSIPATION (mW) 0.001 RL = 8 fIN = 1kHz OUTPUT POWER (mW) 20kHz MAX4364 toc13 THD+N (%) 1 OUTPUT POWER (mW) VCC = 3V AV = 4V/V RL = 8 10 2500 MAX4364 toc10 100 MAX4364 OUTPUT POWER vs. SUPPLY VOLTAGE MAX4364 toc11 MAX4364 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 8 6 4 2 -40 -15 10 35 TEMPERATURE (C) 60 85 0 2.7 3.4 4.1 4.8 5.5 SUPPLY VOLTAGE (V) Maxim Integrated 5 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Typical Operating Characteristics (continued) (VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.) 60 40 1 0.25W 0.5W 0.1 -15 10 60 35 0 100 1k 0.25W 0.5W 0.1 0.01 10k 0.75W 0 MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY VCC = 3V AV = 2V/V RL = 8 0.75W 1 VCC = 3V AV = 4V/V RL = 8 THD+N (%) 0.25W 10 MAX4364 toc23 10 THD+N (%) 0.5W 0.25W 0.1 1 0.4W 0.1 0.4W 0 100 1k 0 0.25W 100 1k 0.01 10k 0 100 1k 10k FREQUENCY (Hz) FREQUENCY (Hz) FREQUENCY (Hz) MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 10 MAX4364 toc27 VCC = 5V AV = 2V/V RL = 8 10 100 MAX4364 toc26 100 MAX4364 toc25 VCC = 3V AV = 20V/V RL = 8 VCC = 5V AV = 4V/V RL = 8 20kHz 0.25W 0.1 1 20Hz 0.1 1kHz 0.01 0.4W 100 1k FREQUENCY (Hz) www.maximintegrated.com 10k 0.001 0 200 300 500 700 1000 1300 1600 2000 2400 OUTPUT POWER (mW) THD+N (%) 20kHz 1 THD+N (%) THD+N (%) 0.01 10k 10 0 10k MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 0.1 0.01 1k FREQUENCY (Hz) 1 0.01 100 FREQUENCY (Hz) VCC = 5V AV = 20V/V RL = 8 MAX4364 toc21 1 TEMPERATURE (C) 10 THD+N (%) 0.01 85 MAX4364 toc22 -40 VCC = 5V AV = 4V/V RL = 8 0.75W 20 0 10 THD+N (%) 80 VCC = 5V AV = 2V/V RL = 8 MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX4364 toc20 10 MAX4364 toc19 VCC = 5V THD+N (%) SUPPLY CURRENT (nA) 100 MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX4364 toc24 MAX4364 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE 20Hz 1 0.1 1kHz 0.01 0.001 500 750 1000 1300 1600 2000 2400 OUTPUT POWER (mW) Maxim Integrated 6 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Typical Operating Characteristics (continued) (VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.) THD+N (%) 1 20Hz 20kHz 0.1 0.01 20kHz 1 20Hz 0.1 1kHz 0.01 1kHz 2500 MAX4364 toc29 VCC = 3V AV = 4V/V RL = 8 10 THD+N (%) VCC = 3V AV = 2V/V RL = 8 10 100 MAX4364 toc28 100 MAX4365 OUTPUT POWER vs. SUPPLY VOLTAGE MAX4364 toc30 MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER OUTPUT POWER (mW) MAX4365 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER RL = 8 fIN = 1kHz 2000 10% THD+N 1500 1000 500 1% THD+N 4.8 5.5 MAX4365 POWER DISSIPATION vs. OUTPUT POWER 400 VCC = 3V fIN = 1kHz 1000 800 600 10% THD+N 400 200 0 10 20 30 40 0 50 800 MAX4364 toc33 1200 POWER DISSIPATION (mW) VCC = 5V fIN = 1kHz MAX4364 toc32 MAX4365 OUTPUT POWER vs. LOAD RESISTANCE OUTPUT POWER (mW) 600 400 200 VCC = 5V RL = 8 fIN = 1kHz 1% THD+N 0 10 20 40 30 0 50 0 300 600 900 1200 1500 LOAD RESISTANCE () OUTPUT POWER (mW) MAX4365 POWER DISSIPATION vs. OUTPUT POWER MAX4365 SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX4365 SUPPLY CURRENT vs. TEMPERATURE 200 150 100 VCC = 3V RL = 8 fIN = 1kHz 50 0 100 200 300 OUTPUT POWER (mW) www.maximintegrated.com 400 500 SUPPLY CURRENT (mA) MAX4364 toc34 7 6 5 4 3 7 2.7 3.4 4.1 4.8 SUPPLY VOLTAGE (V) 5.5 MAX4364 toc36 LOAD RESISTANCE () SUPPLY CURRENT (mA) OUTPUT POWER (mW) 4.1 MAX4365 OUTPUT POWER vs. LOAD RESISTANCE 200 POWER DISSIPATION (mW) 3.4 SUPPLY VOLTAGE (V) 600 0 2.7 OUTPUT POWER (mW) 800 250 0 125 200 250 325 400 500 600 725 850 1000 OUTPUT POWER (mW) 1000 0 0 MAX4364 toc35 1200 0 125 200 250 325 400 500 600 725 800 1000 0.001 MAX4364 toc31 0.001 VCC = 5V 6 5 4 3 -40 -15 10 35 60 85 TEMPERATURE (C) Maxim Integrated 7 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Typical Operating Characteristics (continued) (VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25C, unless otherwise noted.) 8 6 4 2 3.4 4.1 4.8 SUPPLY VOLTAGE (V) 50 40 30 20 0 5.5 -40 -15 10 60 35 85 TEMPERATURE (C) GAIN AND PHASE vs. FREQUENCY POWER-SUPPLY REJECTION RATIO vs. FREQUENCY -20 MAX4364 toc40 2.7 RL = 8 VRIPPLE = 200mVP-P -30 -40 PSRR (dB) 80 60 40 20 0 -20 -40 -60 -80 -100 -120 -140 -160 -180 60 10 MAX4364 toc39 GAIN/PHASE (dB/DEGREES) 0 VCC = 5V 70 SUPPLY CURRENT (nA) 10 SUPPLY CURRENT (nA) 80 MAX4364 toc37 12 MAX4365 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE MAX4364 toc38 MAX4365 SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE -50 -60 -70 AV = 1000V/V 10 100 1k 10k 100k 1M 10M -80 10 100 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) Pin Description PIN MAX4364 MAX4365 SO MAX/TDFN 1 7 SHDN Active-High Shutdown. Connect SHDN to GND for normal operation. 2 1 BIAS DC Bias Bypass. See BIAS Capacitor section for capacitor selection. Connect CBIAS capacitor from BIAS to GND. 3 2 IN+ Noninverting Input 4 4 IN- Inverting Input 5 5 OUT+ 6 6 VCC Power Supply 7 3 GND Ground 8 8 OUT- Bridged Amplifier Negative Output -- -- EP www.maximintegrated.com NAME FUNCTION Bridged Amplifier Positive Output Exposed Pad (TDFN Only). Internally connected to GND. Connect to a large ground plane to maximize thermal performance. Not intended as an electrical connection point. Maxim Integrated 8 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Detailed Description The MAX4364/MAX4365 bridged audio power amplifiers can deliver 1.4W into 8 (MAX4364) or 1W into 8 (MAX4365) while operating from a single 5V supply. These devices consist of two high-output-current op amps configured as a bridge-tied load (BTL) amplifier (see Typical Application Circuit/Functional Diagram). The gain of the device is set by the closed-loop gain of the input op amp. The output of the first amplifier serves as the input to the second amplifier, which is configured as an inverting unity-gain follower in both devices. This results in two outputs, identical in magnitude, but 180 out of phase. BIAS The MAX4364/MAX4365 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 (see Typical Application Circuit/ Functional Diagram). Choose the value of the bypass capacitor as described in the BIAS Capacitor section. Shutdown The MAX4364/MAX4365 feature a 10nA, low-power shutdown mode that reduces quiescent current consumption. Pulling SHDN high disables the device's bias circuitry, the amplifier outputs go high impedance, and BIAS is driven to GND. Connect SHDN to GND for normal operation. Current Limit The MAX4364/MAX4365 feature a current limit that protects the device during output short circuit and overload conditions. When both amplifier outputs are shorted to either VCC or GND, the short-circuit protection is enabled and the amplifier enters a pulsing mode, reducing the average output current to a safe level. The amplifier remains in this mode until the overload or short-circuit condition is removed. Applications Information Bridge-Tied Load The MAX4364/MAX4365 are designed to drive a load differentially in a BTL configuration. 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. Thus, the differential gain of the device is www.maximintegrated.com VOUT(P-P) +1 2 x VOUT(P-P) VOUT(P-P) -1 Figure 1. Bridge-Tied Load Configuration twice the closed-loop gain of the input amplifier. The effective gain is given by: A V D= 2 x RF R IN Substituting 2 VOUT(P-P) into the following equations yields four times the output power due to doubling of the output voltage. VRMS = V O U T (P -P ) PO UT = 2 2 VRMS 2 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 lowfrequency performance. Power Dissipation Under normal operating conditions, the MAX4364/ MAX4365 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: P D IS S P K G (M A X ) = T J(M A X ) - T A JA where TJ(MAX) is +150C, TA is the ambient temperature and JA is the reciprocal of the derating factor in C/W as specified in the Package Thermal Characteristics section. For example, JA of the MAX package is 206.3C/W. Maxim Integrated 9 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown The increase in power delivered by the BTL configuration directly results in an increase in internal power dissipation over the single-ended configuration. The maximum power dissipation for a given VCC and load is given by the following equation: P D IS S P (M A X ) = The MAX4365 TDFN package features an exposed thermal pad on its underside. This pad lowers the thermal resistance of the package by providing a direct heat conduction path from the die to the PC board. Connect the exposed thermal pad to circuit ground by using a large pad, ground plane, or multiple vias to the ground plane. Efficiency The efficiency of the MAX4364/MAX4365 is calculated by taking the ratio of the power delivered to the load to the power consumed from the power supply. Output power is calculated by the following equations: VPEAK 2R L 2 where VPEAK is half the peak-to-peak output voltage. In BTL amplifiers, the supply current waveform is a fullwave rectified sinusoid with the magnitude proportional to the peak output voltage and load. Calculate the supply current and power drawn from the power supply by the following: www.maximintegrated.com PO UT = = P IN 2R L Thermal-overload protection limits total power dissipation in the MAX4364/MAX4365. When the junction temperature exceeds +160C, the thermal protection circuitry disables the amplifier output stage. The amplifiers are enabled once the junction temperature cools by 15C. This results in a pulsing output under continuous thermal overload conditions as the device heats and cools. ICC = The efficiency of the MAX4364/MAX4365 is: 2VCC 2 If the power dissipation for a given application exceeds the maximum allowed for a given package, reduce VCC, increase load impedance, decrease the ambient temperature or add heat sinking to the device. Large output, supply, and ground PC board traces improve the maximum power dissipation in the package. PO UT = 2V P IN = V C C P E A K R L 2VPEAK R L PO U TR L 2 2VCC The device efficiency values in Table 1 are calculated based on the previous equation and do include the effects of quiescent current. Note that efficiency is low at low output-power levels, but remains relatively constant at normal operating, output-power levels. Component Selection Gain-Setting Resistors External feedback components set the gain of both devices. Resistors RF and RIN (see Typical Application Circuit/Functional Diagram) set the gain of the amplifier as follows: A V D= 2 x RF R IN Optimum output offset is achieved when RF = 20k. Vary the gain by changing the value of RIN. When using the MAX4364/MAX4365 in a high-gain configuration (greater than 8V/V), a feedback capacitor may be required to maintain stability (see Figure 2). CF and RF limit the bandwidth of the device, preventing high-frequency oscillations. Ensure that the pole created by CF and RF is not within the frequency band of interest. 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 -3D B = 1 2 R IN C IN Choose RIN according to the Gain-Setting Resistors section. Choose 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 amplifier. Use capacitors whose dielectrics have low-voltage coeffi- Maxim Integrated 10 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown VCC 6 VCC 50k 2 50k 3 AUDIO INPUT SHDN 1 OUT- 8 BIAS CBIAS CIN CLICKLESS/ POPLESS SHUTDOWN CONTROL IN+ 10k 10k OUT+ 5 RIN 4 IN- MAX4364 MAX4365 GND 7 RF CF Figure 2. High-Gain Configuration Table 1. Efficiency in a 5V, 8 BTL System OUTPUT POWER (W) INTERNAL POWER DISSIPATION (W) EFFICIENCY (%) 0.25 0.55 31.4 0.50 0.63 44.4 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. 0.75 0.63 54.4 BIAS Capacitor 1.00 0.59 62.8 1.25 0.53 70.2 1.40 0.48 74.3 The BIAS bypass capacitor, CBIAS, improves PSRR and THD+N by reducing power-supply noise at the commonmode bias node, and serves as the primary clickandpop 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 click-and-pop suppression is given by: cients, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as ceramics, may result in an increase distortion at low frequencies. 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 www.maximintegrated.com C R C B IA S 1 0 IN IN 2 5k In addition, a larger CBIAS value yields higher PSRR. Maxim Integrated 11 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Clickless/Popless Operation RF Proper selection of AC-coupling capacitors (CIN) and CBIAS achieves clickless/popless shutdown and startup. The value of CBIAS determines the rate at which the midrail 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, optimizing click-and-pop suppression. AUDIO INPUT 1 H MAX5407 OUT+ RIN W 3 MAX4364 INMAX4365 CIN 4 L OUT- Figure 3. MAX4364/MAX4365 and MAX5160 Volume Control Circuit Supply Bypassing passes the audio signal unattenuated. Setting the wiper to the lowest position fully attenuates the input. Proper supply bypassing ensures low-noise, low-distortion performance. Place a 0.1F ceramic capacitor in parallel with a 10F ceramic capacitor from VCC to GND. Locate the bypass capacitors as close to the device as possible. 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 surface-mount components and placing external components as close to the device as possible. Also refer to the Power Dissipation section for heatsinking considerations. Adding Volume Control The addition of a digital potentiometer provides simple volume control. Figure 3 shows the MAX4364/MAX4365 with the MAX5407 log taper digital potentiometer used as an input attenuator. Connect the high terminal of the MAX5407 to the audio input, the low terminal to ground and the wiper to CIN. Setting the wiper to the top position Chip Information PROCESS: BiCMOS Pin Configurations TOP VIEW OUT- SHDN VCC OUT+ SHDN 1 BIAS 2 IN+ IN- + 8 OUT- 7 GND 3 6 VCC 4 5 OUT+ MAX4364 SO BIAS 1 IN+ 2 GND 3 IN- 4 + MAX4365 MAX 8 OUT- 7 SHDN 6 VCC 5 OUT+ 8 7 6 5 MAX4364 MAX4365 EP* + 1 2 3 4 BIAS IN+ GND IN- TDFN *CONNECT EP TO GND. www.maximintegrated.com Maxim Integrated 12 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 8 SO S8+5 21-0041 90-0096 8 MAX U8+1 21-0036 90-0092 8 TDFN T833+2 21-0137 90-0059 www.maximintegrated.com Maxim Integrated 13 MAX4364/MAX4365 1.4W and 1W, Ultra-Small, Audio Power Amplifiers with Shutdown Revision History REVISION NUMBER REVISION DATE PAGES CHANGED 4 5/11 Added EP information to Pin Description; updated Ordering Information and Pin Configurations for lead-free parts; updated specifications in Absolute Maximum Ratings, Package Thermal Characteristics and Electrical Characteristics sections 5 6/17 Changed orderable part number from MAX4364ESA+ to MAX4364ESA/V+T in Ordering Information table DESCRIPTION 1, 2, 3, 8, 9, 12, 13 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated's website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. (c) 2017 Maxim Integrated Products, Inc. 14 Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Maxim Integrated: MAX4364ESA+ MAX4364ESA+T MAX4364ESA/V+ MAX4364ESA/V+T