19-3049; Rev 2; 10/07 KIT ATION EVALU LE B A IL A AV 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown The MAX9722A/MAX9722B stereo headphone amplifiers are designed for portable equipment where board space is at a premium. The MAX9722A/MAX9722B use a unique, patented DirectDrive architecture to produce a ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors, which saves cost, board space, and component height. Additionally, the gain of the amplifier is set internally (-2V/V, MAX9722B) or adjusted externally (MAX9722A). The MAX9722A/MAX9722B deliver up to 70mW per channel into a 16Ω load or 130mW into a 32Ω load and have low 0.009% THD+N. An 80dB at 217Hz power-supply rejection ratio (PSRR) allows these devices to operate from noisy digital supplies without an additional linear regulator. The MAX9722A/MAX9722B include ±8kV ESD protection on the headphone outputs. Comprehensive anticlick-and-pop circuitry suppresses audible clicks and pops on startup and shutdown. A low-power shutdown mode reduces the supply current to 0.1µA. The MAX9722A/MAX9722B operate from a single 2.4V to 5.5V supply, consume only 5.5mA of supply current, feature short-circuit and thermal-overload protection, and are specified over the extended -40°C to +85°C temperature range. The devices are available in tiny 16-pin thin QFN (3mm ✕ 3mm ✕ 0.8mm) and 16-pin TSSOP packages. Applications Notebook and Desktop PCs Smart Phones MP3 Players Portable Audio Equipment ♦ 2.4V to 5.5V Single-Supply Operation ♦ High PSRR (80dB at 217Hz) Eliminates LDO ♦ No Bulky DC-Blocking Capacitors Required ♦ Ground-Referenced Outputs Eliminate DC Bias Voltage on Headphone Ground Pin ♦ No Degradation of Low-Frequency Response Due to Output Capacitors ♦ Differential Inputs for Enhanced Noise Cancellation ♦ Adjustable Gain (MAX9722A) or Fixed -2V/V Gain (MAX9722B) ♦ 130mW per Channel into 32Ω ♦ Low 0.009% THD+N ♦ Integrated Click-and-Pop Suppression ♦ Low Quiescent Current (5.5mA) ♦ Short-Circuit and Thermal-Overload Protection ♦ ±8kV ESD-Protected Amplifier Outputs (Human Body Model) ♦ Available in a Space-Saving 16-Pin Thin QFN (3mm ✕ 3mm ✕ 0.8mm) Package Simplified Diagram PDAs Flat-Panel Monitors Cellular Phones Ordering Information PART Features PIN-PACKAGE TOP MARK PKG CODE SHDN MAX9722AETE 16 Thin QFN-EP* (3mm ✕ 3mm ✕ 0.8mm) MAX9722AEUE 16 TSSOP MAX9722BETE 16 Thin QFN-EP* (3mm ✕ 3mm ✕ 0.8mm) MAX9722BEUE 16 TSSOP AAX T1633-5 — U16-1 AAY T1633-5 — U16-1 Note: All devices are specified over the -40°C to +85°C operating temperature range. *EP = Exposed paddle. DirectDrive OUTPUTS ELIMINATE DC-BLOCKING CAPACITORS. LEFT AUDIO INPUT RIGHT AUDIO INPUT MAX9722B FIXED GAIN ELIMINATES EXTERNAL RESISTOR NETWORK. Pin Configurations and Typical Operating Circuit appear at end of data sheet. ________________________________________________________________ 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 MAX9722A/MAX9722B General Description MAX9722A/MAX9722B 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown ABSOLUTE MAXIMUM RATINGS PVSS to SVSS ............................................................................0V Output Short Circuit to GND.......................................Continuous Continuous Power Dissipation (TA = +70°C) 16-Pin Thin QFN (derate 14.7mW/°C above +70°C)....1176mW 16-Pin TSSOP (derate 9.4mW/°C above +70°C) .........755mW Junction Temperature ......................................................+150°C Operating Temperature Range............................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C PGND to SGND .....................................................-0.3V to +0.3V PVDD and SVDD to PGND or SGND .........................-0.3V to +6V PVSS and SVSS to PGND..........................................+0.3V to -6V IN_ to SGND ................................(SVSS - 0.3V) to (SVDD + 0.3V) OUT_ to PGND ......................................................-3.0V to +3.0V SHDN to SGND..........................(SGND - 0.3V) to (SVDD + 0.3V) C1P to PGND ...........................................-0.3V to (PVDD + 0.3V) C1N to PGND............................................(SVSS - 0.3V) to +0.3V PVDD to SVDD ...........................................................................0V 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 (PVDD = SVDD = +5V, PGND = SGND = 0V, SHDN = SVDD, C1 = C2 = 1µF, RL = ∞, resistive load referenced to ground, for MAX9722A gain = -1V/V (RIN = RF = 10kΩ), for MAX9722B gain = -2V/V (internally set), TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS GENERAL Supply Voltage Range VDD Guaranteed by PSRR test 5.5 V Quiescent Supply Current IDD RL = ∞ 5.5 13 mA Shutdown Supply Current ISHDN SHDN = SGND 0.1 2 µA 0.8 V +1 µA SHDN Input Logic High VIH SHDN Input Logic Low VIL 2 SHDN Input Leakage Current SHDN to Full Operation Time 2.4 -1 tSON V +0.05 80 µs AMPLIFIERS Voltage Gain AV Gain Matching Input Offset Voltage VIS IBIAS Input Impedance RIN Input Common-Mode Voltage Range VCM Power-Supply Rejection Ratio (Note 3) CMRR PSRR Output Power POUT Output Voltage VOUT Output Impedance in Shutdown 2 -1.98 -2 -2.02 ±2 MAX9722B, between the right and left channels Input Bias Current Common-Mode Rejection Ratio MAX9722B (Note 2) % Between IN_+ and IN_-, AC-coupled (MAX9722A) ±0.5 ±2.5 Between IN_+ and IN_-, AC-coupled (MAX9722B) ±1.5 ±5 IN_+ and IN_MAX9722B, measured at IN_ 50 10 14.4 -0.5 Input referred, MAX9722A, TA = +25°C -60 -70 DC, VDD = 2.4V to 5.5V, input referred -80 -90 f = 217Hz, 100mVP-P ripple, input referred -80 f = 10kHz, 100mVP-P ripple, input referred -50 RL = 16Ω, THD+N = 1%, TA = +25°C RL = 32Ω, THD+N = 1%, TA = +25°C RL = 1kΩ 60 70 130 V/V mV nA 20 kΩ +0.7 V dB dB mW 2 VRMS 10 kΩ _______________________________________________________________________________________ 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown (PVDD = SVDD = +5V, PGND = SGND = 0V, SHDN = SVDD, C1 = C2 = 1µF, RL = ∞, resistive load referenced to ground, for MAX9722A gain = -1V/V (RIN = RF = 10kΩ), for MAX9722B gain = -2V/V (internally set), TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL Total Harmonic Distortion Plus Noise (Note 4) THD+N Signal-to-Noise Ratio SNR Noise Vn Slew Rate SR Maximum Capacitive Load CL Charge-Pump Oscillator Frequency CONDITIONS MIN TYP RL = 16Ω, POUT = 55mW, f = 1kHz 0.03 RL = 32Ω, POUT = 125mW, f = 1kHz 0.009 RL = 32Ω, POUT = 20mW, f = 22Hz to 22kHz fOSC 505 UNITS % 100 dB 6 µVRMS 0.5 V/µs 200 pF 22Hz to 22kHz bandwidth, input AC grounded No sustained oscillation MAX 600 800 kHz Crosstalk RL = 32Ω, VIN = 200mVP-P, f = 10kHz, AV = 1 78 dB ESD Protection Human Body Model (OUTR and OUTL) ±8 kV Thermal-Shutdown Threshold 145 °C Thermal-Shutdown Hysteresis 5 °C Note 1: Note 2: Note 3: Note 4: All specifications are 100% tested at TA = +25°C; temperature limits are guaranteed by design. Gain for the MAX9722A is adjustable. The amplifier inputs are AC-coupled to ground through CIN_. Measurement bandwidth is 22Hz to 22kHz. Typical Operating Characteristics (MAX9722A, PVDD = SVDD = +5V, PGND = SGND = 0V, SHDN = SVDD, C1 = C2 = 1µF, RL = ∞, gain = -1V/V, single-ended input, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.) 0.01 0.1 0.01 POUT = 40mW 1k FREQUENCY (Hz) 0.1 MAX9722 toc03 POUT = 60mW 0.01 0.001 0.0001 0.0001 100 1 POUT = 5mW POUT = 20mW 0.001 0.0001 10 VDD = 5V AV = -1V/V RL = 16Ω POUT = 40mW POUT = 30mW 0.001 1 10 POUT = 5mW POUT = 15mW 0.1 VDD = 3V AV = -1V/V RL = 32Ω THD+N (%) POUT = 5mW 10 THD+N (%) THD+N (%) 1 VDD = 3V AV = -1V/V RL = 16Ω MAX9722 toc01 10 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX9722 toc02 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 10k 100k 10 100 1k FREQUENCY (Hz) 10k 100k 10 100 1k 10k 100k FREQUENCY (Hz) _______________________________________________________________________________________ 3 MAX9722A/MAX9722B ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (MAX9722A, PVDD = SVDD = +5V, PGND = SGND = 0V, SHDN = SVDD, C1 = C2 = 1µF, RL = ∞, gain = -1V/V, single-ended input, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.) 0.01 VDD = 5V AV = -1V/V RL = 32Ω 1 THD+N (%) POUT = 20mW 10 1 POUT = 5mW 0.1 POUT = 20mW 0.01 POUT = 5mW 0.1 POUT = 20mW 0.01 POUT = 40mW 0.001 0.0001 1k 10k 100k 0.0001 100 10 1k 10k 100k TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 10 f = 1kHz f = 1kHz 0.1 0.01 VDD = 3V AV = -1V/V RL = 16Ω f = 20Hz 0.001 0.0001 10 20 30 40 50 60 0.01 0.001 VDD = 3V AV = -1V/V RL = 32Ω f = 20Hz 0.0001 70 0 10 20 30 40 50 60 70 f = 20Hz 0.001 VDD = 5V AV = -1V/V RL = 16Ω 0.0001 80 0 10 20 30 40 50 60 70 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 THD+N (%) 1 f = 1kHz 0.1 1 f = 10kHz f = 1kHz 0.1 0.01 0.01 f = 20Hz 0.001 20 30 40 50 OUTPUT POWER (mW) 60 70 f = 1kHz 0.1 0.001 f = 20Hz 0.0001 10 f = 10kHz 0.01 0.001 0.0001 VDD = 5V AV = -2V/V RL = 32Ω 10 THD+N (%) f = 10kHz VDD = 5V AV = -1V/V RL = 32Ω 10 100 MAX9722 toc11 MAX9722 toc10 100 MAX9722 toc12 OUTPUT POWER (mW) VDD = 5V AV = -2V/V RL = 16Ω 0 f = 10kHz 1 f = 10kHz 0.1 0.01 10 THD+N (%) THD+N (%) f = 1kHz 100 MAX9722 toc08 100 MAX9722 toc07 f = 10kHz 0.1 1 100k TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 1 10 10k FREQUENCY (Hz) 1 100 1k FREQUENCY (Hz) 10 0 100 10 FREQUENCY (Hz) 100 THD+N (%) 0.001 0.0001 100 10 4 POUT = 80mW POUT = 80mW 0.001 VDD = 5V AV = -2V/V RL = 32Ω MAX9722 toc09 0.1 10 THD+N (%) POUT = 5mW 1 THD+N (%) VDD = 5V AV = -2V/V RL = 16Ω MAX9722 toc04 10 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX9722 toc06 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX9722 toc05 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY THD+N (%) MAX9722A/MAX9722B 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown f = 20Hz 0.0001 0 20 40 60 80 100 OUTPUT POWER (mW) 120 140 0 20 40 60 80 100 OUTPUT POWER (mW) _______________________________________________________________________________________ 120 140 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown (MAX9722A, PVDD = SVDD = +5V, PGND = SGND = 0V, SHDN = SVDD, C1 = C2 = 1µF, RL = ∞, gain = -1V/V, single-ended input, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.) 1 f = 1kHz THD+N (%) 0.1 0.01 90 80 RL = 16Ω 0.1 0.01 RL = 32Ω 0.001 20 30 40 50 60 -0.5 -0.1 0.1 0.3 2.4 0.5 2.6 2.8 3.0 3.2 THD+N = 1% 100 80 60 f = 1kHz RL = 32Ω 20 0 70 THD+N = 10% 60 50 THD+N = 1% 40 30 160 3.4 3.9 4.4 140 THD+N = 1% 100 80 60 40 10 20 4.9 THD+N = 10% 120 20 0 0 2.9 VDD = 5V f = 1kHz AV = -1V/V 180 OUTPUT POWER (mW) 80 200 MAX9722 toc17 MAX9722 toc16 THD+N = 10% 140 VDD = 3V f = 1kHz AV = -1V/V 90 MAX9722 toc18 OUTPUT POWER vs. LOAD RESISTANCE 100 10 100 10 1000 1000 100 SUPPLY VOLTAGE (V) LOAD RESISTANCE (Ω) LOAD RESISTANCE (Ω) POWER DISSIPATION vs. OUTPUT POWER POWER DISSIPATION vs. OUTPUT POWER POWER-SUPPLY REJECTION RATIO vs. FREQUENCY RL = 16Ω 150 100 RL = 32Ω 0 -20 -30 400 RL = 16Ω 300 RL = 32Ω 200 50 100 0 0 VDD = 3V AV = -1V/V RL = 32Ω -10 PSRR (dB) 200 VDD = 5V f = 1kHz POUT = PL + PR 500 POWER DISSIPATION (mW) VDD = 3V f = 1kHz POUT = PL + PR MAX9722 toc20 600 MAX9722 toc19 300 3.6 3.4 OUTPUT POWER vs. LOAD RESISTANCE 40 POWER DISSIPATION (mW) -0.3 OUTPUT POWER vs. SUPPLY VOLTAGE OUTPUT POWER (mW) OUTPUT POWER (mW) 70 SUPPLY VOLTAGE (V) 160 250 f = 1kHz RL = 16Ω COMMON-MODE VOLTAGE (V) 180 2.4 30 OUTPUT POWER (mW) 200 120 40 0 0.0001 10 THD+N = 1% 50 10 0.0001 0 60 20 0.001 f = 20Hz THD+N = 10% 70 MAX9722 toc21 THD+N (%) 1 10 100 MAX9722 toc15 f = 10kHz VDD = 5V AV = -1V/V f = 1kHz DIFFERENTIAL OUTPUT POWER (mW) 10 100 MAX9722 toc14 VDD = 5V AV = -1V/V RL = 16Ω DIFFERENTIAL MAX9722 toc13 100 OUTPUT POWER vs. SUPPLY VOLTAGE TOTAL HARMONIC DISTORTION PLUS NOISE vs. COMMON-MODE VOLTAGE TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER -40 -50 RIGHT -60 -70 LEFT -80 -90 0 10 20 30 40 50 OUTPUT POWER (mW) 60 70 -100 0 20 40 60 OUTPUT POWER (mW) 80 100 10 100 1k 10k 100k FREQUENCY (Hz) _______________________________________________________________________________________ 5 MAX9722A/MAX9722B Typical Operating Characteristics (continued) Typical Operating Characteristics (continued) (MAX9722A, PVDD = SVDD = +5V, PGND = SGND = 0V, SHDN = SVDD, C1 = C2 = 1µF, RL = ∞, gain = -1V/V, single-ended input, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.) CROSSTALK vs. FREQUENCY -20 -40 -50 -60 -70 -40 -50 -60 -20 RIGHT TO LEFT -70 RIGHT -80 -80 -90 -90 LEFT 10k 100 1k 100k 10k FREQUENCY (Hz) GAIN FLATNESS vs. FREQUENCY CHARGE-PUMP OUTPUT RESISTANCE vs. SUPPLY VOLTAGE 10 1 0 -1 -2 8 100 1k OUTPUT POWER vs. LOAD RESISTANCE 60 C1 = C2 = 2.2µF 50 7 6 5 4 3 40 30 C1 = C2 = 1µF C1 = C2 = 0.68µF C1 = C2 = 0.47µF 20 10 100 1k 10k 100k 2.4 2.8 3.2 3.6 4.0 4.4 4.8 5.2 10 5.6 20 30 SUPPLY VOLTAGE (V) LOAD RESISTANCE (Ω) OUTPUT SPECTRUM vs. FREQUENCY SUPPLY CURRENT vs. SUPPLY VOLTAGE SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE -30 -40 -50 -60 -70 5 4 3 1 10 FREQUENCY (kHz) 15 20 16 14 12 10 8 6 2 0 0 5 18 4 -80 -100 MAX9722 toc30 MAX9722 toc29 6 2 -90 20 SUPPLY CURRENT (nA) -20 7 SUPPLY CURRENT (mA) -10 8 MAX9722 toc28 VDD = 5V RL = 32Ω VOUT = 1mVRMS f = 1kHz AV = -1V/V 0 50 40 FREQUENCY (Hz) 10 0 VDD = 3V f = 1kHz AV = -1V/V THD+N = 1% 0 0 10 100k 10k 1 -4 6 LEFT TO RIGHT 10 2 -3 RIGHT TO LEFT FREQUENCY (Hz) VIN = GND IPVSS = 10mA C1 = C2 = 2.2µF NO LOAD 9 OUTPUT RESISTANCE (Ω) 2 -60 -90 FREQUENCY (Hz) VDD = 5V AV = -1V/V RL = 32Ω 3 10 100k -50 -100 OUTPUT POWER (mW) 1k -40 -80 LEFT TO RIGHT MAX9722 toc26 4 100 MAX9722 toc25 10 -30 -70 -100 -100 GAIN (dB) -30 VDD = 5V AV = -1V/V VIN = 200mVP-P RL = 32Ω -10 MAX9722 toc27 CROSSTALK (dB) PSRR (dB) -30 VDD = 3V AV = -1V/V VIN = 200mVP-P RL = 32Ω -10 CROSSTALK (dB) -20 CROSSTALK vs. FREQUENCY 0 MAX9722 toc23 VDD = 5V AV = -1V/V RL = 32Ω -10 0 MAX9722 toc22 0 MAX9722 toc24 POWER-SUPPLY REJECTION RATIO vs. FREQUENCY OUTPUT (dBc) MAX9722A/MAX9722B 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown 0 1 2 3 4 SUPPLY VOLTAGE (V) 5 0 1 2 3 4 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown (MAX9722A, PVDD = SVDD = +5V, PGND = SGND = 0V, SHDN = SVDD, C1 = C2 = 1µF, RL = ∞, gain = -1V/V, single-ended input, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.) EXIT SHUTDOWN TRANSIENT POWER-UP/DOWN TRANSIENT SHUTDOWN TRANSIENT MAX9722 toc31 MAX9722 toc33 MAX9722 toc32 SHDN 2V/div SHDN 2V/div VDD 2V/div OUT 500mV/div OUT 500mV/div OUT 5mV/div 200µs/div 20ms/div 400µs/div Pin Description PIN THIN QFN TSSOP 1 3 NAME FUNCTION PVDD Charge-Pump Power Supply. Powers charge-pump inverter, charge-pump logic, and oscillator. Connect to positive supply (2.4V to 5.5V). Bypass with a 1µF capacitor to PGND as close to the pin as possible. 2 4 C1P Flying Capacitor Positive Terminal 3 5 PGND Power Ground. Connect to ground. 4 6 C1N Flying Capacitor Negative Terminal Charge-Pump Output. Connect to SVSS. 5 7 PVSS 6 8 SGND Signal Ground. Connect to ground. 7 9 INR+ Noninverting Right-Channel Audio Input 8 10 INR- Inverting Right-Channel Audio Input 9, 13 11, 15 SVDD Amplifier Positive Power Supply. Connect to positive supply (2.4V to 5.5V). Bypass with a 1µF capacitor to SGND as close to the pin as possible. 10 12 OUTR Right-Channel Output 11 13 SVSS Amplifier Negative Power Supply. Connect to PVSS. 12 14 OUTL 14 16 INL- Inverting Left-Channel Audio Input 15 1 INL+ Noninverting Left-Channel Audio Input 16 2 SHDN Active-Low Shutdown Input — — EP Left-Channel Output Exposed Paddle. The exposed paddle can be either connected to PVSS or a small electrically isolated copper plane. Do not connect to PGND, SGND, PVDD, or SVDD. _______________________________________________________________________________________ 7 MAX9722A/MAX9722B Typical Operating Characteristics (continued) MAX9722A/MAX9722B 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown Detailed Description The MAX9722A/MAX9722B stereo headphone amplifiers feature Maxim’s patented DirectDrive architecture, eliminating the large output-coupling capacitors required by conventional single-supply headphone amplifiers. The devices consist of two class AB headphone amplifiers, undervoltage lockout (UVLO)/shutdown control, charge pump, and comprehensive click-and-pop suppression circuitry (see Typical Application Circuit). The charge pump inverts the positive supply (PVDD), creating a negative supply (PVSS). The headphone amplifiers operate from these bipolar supplies with their outputs biased about GND (Figure 1). The benefit of this GND bias is that the amplifier outputs do not have a DC component, typically V DD /2. The large DC-blocking capacitors required with conventional headphone amplifiers are unnecessary, thus conserving board space, reducing system cost, and improving frequency response. The device features an undervoltage lockout that prevents operation from an insufficient power supply and clickand-pop suppression that eliminates audible transients on startup and shutdown. Additionally, the MAX9722A/ MAX9722B feature thermal-overload and short-circuit protection and can withstand ±8kV ESD strikes at the output pins. VDD VOUT VDD/2 GND CONVENTIONAL DRIVER-BIASING SCHEME +VDD OR 3V VOUT GND -VDD OR -3V Differential Input The MAX9722 can be configured as a differential input amplifier (Figure 2), making it compatible with many CODECs. A differential input offers improved noise immunity over a single-ended input. In devices such as cellular phones, high-frequency signals from the RF transmitter can couple into the amplifier’s input traces. The signals appear at the amplifier’s inputs as common-mode noise. A differential input amplifier amplifies the difference of the two inputs, and signals common to both inputs are cancelled. Configured differentially, the gain of the MAX9722 is set by: AV = RF1/RIN1 RIN1 must be equal to RIN2, and RF1 must be equal to RF2. The common-mode rejection ratio (CMRR) is limited by the external resistor matching. For example, the worstcase variation of 1% tolerant resistors results in 40dB CMRR, while 0.1% resistors result in 60dB CMRR. For best matching, use resistor arrays. The RIN1 and RF1 of the MAX9722B are internal, set R IN2 = 15kΩ and R F2 = 30kΩ. However, for best results, use the MAX9722A. 8 DirectDrive BIASING SCHEME Figure 1. Conventional Driver Output Waveform vs. MAX9722A/ MAX9722B Output Waveform RF1* RIN1* INOUT RIN2 IN+ RF2 RIN1 = RIN2, RF1 = RF2 *RIN1 AND RF1 ARE INTERNAL FOR MAX9722B. Figure 2. Differential Input Configuration _______________________________________________________________________________________ 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown Low-Frequency Response In addition to the cost and size disadvantages of the DCblocking capacitors required by conventional head- MAX9722A/MAX9722B DirectDrive Conventional single-supply headphone amplifiers have their outputs biased about a nominal DC voltage (typically half the supply) for maximum dynamic range. Large coupling capacitors are needed to block this DC bias from the headphone. Without these capacitors, a significant amount of DC current flows to the headphone, resulting in unnecessary power dissipation and possible damage to both the headphone and the headphone amplifier. Maxim’s patented DirectDrive architecture uses a charge pump to create an internal negative supply voltage, allowing the MAX9722A/MAX9722B outputs to be biased about GND. With no DC component, there is no need for the large DC-blocking capacitors. Instead of two large (220µF, typ) tantalum capacitors, the MAX9722A/MAX9722B charge pump requires two small ceramic capacitors, conserving board space, reducing cost, and improving the frequency response of the headphone amplifier. See the Output Power vs. Load Resistance graph in the Typical Operating Characteristics for details of the possible capacitor sizes. There is a low DC voltage on the amplifier outputs due to amplifier offset. However, the offset of the MAX9722A is typically 0.5mV, which, when combined with a 32Ω load, results in less than 15.6µA of DC current flow to the headphones. Previous attempts to eliminate the output-coupling capacitors involved biasing the headphone return (sleeve) to the DC-bias voltage of the headphone amplifiers. This method raises some issues: • The sleeve is typically grounded to the chassis. Using this biasing approach, the sleeve must be isolated from system ground, complicating product design. • During an ESD strike, the amplifier’s ESD structures are the only path to system ground. Thus, the amplifier must be able to withstand the full ESD strike. • When using the headphone jack as a line out to other equipment, the bias voltage on the sleeve may conflict with the ground potential from other equipment, resulting in possible damage to the amplifiers. • When using a combination microphone and speaker headset, the microphone typically requires a GND reference. The amplifier DC bias on the sleeve conflicts with the microphone requirements (Figure 3). MICROPHONE BIAS MICROPHONE AMPLIFIER MICROPHONE AMPLIFIER OUTPUT AUDIO INPUT MAX9722 AUDIO INPUT HEADPHONE DRIVER Figure 3. Earbud Speaker/Microphone Combination Headset Configuration phone amplifiers, these capacitors limit the amplifier’s low-frequency response and can distort the audio signal: 1) The impedance of the headphone load and the DCblocking capacitor form a highpass filter with the -3dB point set by: f-3dB = 1 2πRLCOUT where R L is the impedance of the headphone and COUT is the value of the DC-blocking capacitor. The highpass filter is required by conventional singleended, single power-supply headphone amplifiers to block the midrail DC-bias component of the audio signal from the headphones. The drawback to the filter is that it can attenuate low-frequency signals. Larger values of COUT reduce this effect but result in physically larger, more expensive capacitors. Figure 4 shows the relationship between the size of COUT and the resulting low-frequency attenuation. Note that the -3dB point for a 16Ω headphone with a 100µF blocking capacitor is 100Hz, well within the normal audio band, resulting in low-frequency attenuation of the reproduced signal. _______________________________________________________________________________________ 9 ADDITIONAL THD+N DUE TO DC-BLOCKING CAPACITORS LOW-FREQUENCY ROLLOFF (RL = 16Ω) 0 10 -3 DirectDrive -6 -9 1 330µF -12 THD+N (%) ATTENUATION (dB) MAX9722A/MAX9722B 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown 220µF -15 100µF -18 0.1 TANTALUM 0.01 33µF -21 -24 0.001 ALUM/ELEC -27 -30 0.0001 10 100 1k 10k 100k FREQUENCY (Hz) Figure 4. Low-Frequency Attenuation for Common DC-Blocking Capacitor Values 2) The voltage coefficient of the DC-blocking capacitor contributes distortion to the reproduced audio signal as the capacitance value varies and the function of the voltage across the capacitor changes. The reactance of the capacitor dominates at frequencies below the -3dB point and the voltage coefficient appears as frequency-dependent distortion. Figure 5 shows the THD+N introduced by two different capacitor dielectric types. Note that below 100Hz, THD+N increases rapidly. The combination of low-frequency attenuation and frequency-dependent distortion compromises audio reproduction in portable audio equipment that emphasizes low-frequency effects such as in multimedia laptops, MP3, CD, and DVD players. By eliminating the DC-blocking capacitors through DirectDrive technology, these capacitor-related deficiencies are eliminated. Charge Pump The MAX9722A/MAX9722B feature a low-noise charge pump. The 600kHz switching frequency is well beyond the audio range and, thus, does not interfere with the audio signals. Also, the 600kHz switching frequency does not interfere with the 450kHz AM transceivers. The switch drivers feature a controlled switching speed that minimizes noise generated by turn-on and turn-off transients. By limiting the switching speed of the charge pump, the di/dt noise caused by the parasitic bond wire and trace inductance is minimized. Although not typically required, additional high-frequency noise attenuation can be achieved by increasing the value of C2 (see Typical Application Circuit). 10 10 100 1k 10k 100k FREQUENCY (Hz) Figure 5. Distortion Contributed by DC-Blocking Capacitors Click-and-Pop Suppression In conventional single-supply audio amplifiers, the output-coupling capacitor is a major contributor of audible clicks and pops. Upon startup, the amplifier charges the coupling capacitor to its bias voltage, typically half the supply. Likewise, on shutdown, the capacitor is discharged to GND. This results in a DC shift across the capacitor, which, in turn, appears as an audible transient at the speaker. Since the MAX9722A/MAX9722B do not require output-coupling capacitors, this problem does not arise. Additionally, the MAX9722A/MAX9722B feature extensive click-and-pop suppression that eliminates any audible transient sources internal to the device. The Power-Up/Down Transient graph in the Typical Operating Characteristics shows that there is minimal DC shift and no spurious transients at the output upon startup or shutdown. In most applications, the output of the preamplifier driving the MAX9722A/MAX9722B has a DC bias of typically half the supply. At startup, the input-coupling capacitor is charged to the preamplifier’s DC-bias voltage through the feedback resistor of the MAX9722A/MAX9722B, resulting in a DC shift across the capacitor and an audible click/pop. Delaying the rise of SHDN 4 to 5 time constants (80ms to 100ms) based on RIN and CIN, relative to the startup of the preamplifier, eliminates this click/pop caused by the input filter. ______________________________________________________________________________________ 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown Power Dissipation Under normal operating conditions, linear power amplifiers 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: PDISSPKG(MAX) = TJ(MAX) - TA θJA where TJ(MAX) is +145°C, TA is the ambient temperature, and θJA is the reciprocal of the derating factor in °C/W as specified in the Absolute Maximum Ratings section. For example, θJA of the thin QFN package is +63.8°C/W, and 99.3°C/W for the TSSOP package. The MAX9722A/MAX9722B have two power dissipation sources: the charge pump and two amplifiers. If power dissipation for a given application exceeds the maximum allowed for a particular package, either reduce SVDD, increase load impedance, decrease the ambient temperature, or add heatsinking 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 MAX9722A/MAX9722B. When the junction temperature exceeds +145°C, the thermal-protection circuitry disables the amplifier output stage. The amplifiers are enabled once the junction temperature cools by 5°C. This results in a pulsing output under continuous thermal-overload conditions. Output Power The device has been specified for the worst-case scenario—when both inputs are in-phase. Under this condition, the amplifiers simultaneously draw current from the charge pump, leading to a slight loss in SVSS headroom. In typical stereo audio applications, the left and right signals have differences in both magnitude and phase, subsequently leading to an increase in the max- fIN = 1kHz RL = 32Ω THD+N = 10% MAX9722 fig06 140 OUTPUT POWER (mW) Applications Information OUTPUT POWER vs. SUPPLY VOLTAGE 160 INPUTS 180° OUT OF PHASE 120 100 80 60 INPUTS IN PHASE 40 20 0 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 SUPPLY VOLTAGE (V) Figure 6. Output Power vs. Supply Voltage With Inputs In/Out of Phase imum attainable output power. Figure 6 shows the two extreme cases for in- and out-of-phase. In reality, the available power lies between these extremes. Powering Other Circuits from a Negative Supply An additional benefit of the MAX9722A/MAX9722B is the internally generated, negative supply voltage (PVSS). This voltage provides the ground-referenced output level. PVSS can, however, be used to power other devices within a design limit current drawn from PVSS to 5mA; exceeding this affects the headphone amplifier operation. A typical application is a negative supply to adjust the contrast of LCD modules. PVSS is roughly proportional to PVDD and is not a regulated voltage. The charge-pump output impedance must be taken into account when powering other devices from PVSS. The charge-pump output impedance plot appears in the Typical Operating Characteristics. For best results, use 1µF charge-pump capacitors. UVLO The MAX9722A/MAX9722B feature an UVLO function that prevents the device from operating if the supply voltage is less than 2.2V (typ). This feature ensures proper operation during brownout conditions and prevents deep battery discharge. Once the supply voltage reaches the UVLO threshold, the MAX9722A/ MAX9722B charge pump is turned on and the amplifiers are powered. ______________________________________________________________________________________ 11 MAX9722A/MAX9722B Shutdown The MAX9722A/MAX9722B feature shutdown control allowing audio signals to be shut down or muted. Driving SHDN low disables the amplifiers and the charge pump, sets the amplifier output impedance to 10kΩ, and reduces the supply current. In shutdown mode, the supply current is reduced to 0.1µA. The charge pump is enabled once SHDN is driven high. MAX9722A/MAX9722B 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown Component Selection Input Filtering The input capacitor (CIN), in conjunction with the input resistor (RIN), forms a highpass filter that removes the DC bias from an incoming signal (see the Typical Application Circuit). The AC-coupling capacitor allows the device 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 2πRINCIN RF LEFT AUDIO INPUT RIN INL- MAX9722A OUTL INL+ INR+ OUTR Choose CIN so f-3dB is well below the lowest frequency of interest. For the MAX9722B, use the value of RIN as given in the Electrical Characteristics table. Setting f-3dB too high affects the device’s low-frequency response. Use capacitors whose dielectrics have low-voltage coefficients, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as ceramics, can result in increased distortion at low frequencies. Charge-Pump Capacitor Selection Use capacitors with an ESR less than 100mΩ for optimum performance. Low-ESR ceramic capacitors minimize the output resistance of the charge pump. For best performance over the extended temperature range, select capacitors with an X7R dielectric. Table 1 lists suggested manufacturers. Flying Capacitor (C1) The value of the flying capacitor (C1) affects the charge pump’s load regulation and output resistance. A C1 value that is too small degrades the device’s ability to provide sufficient current drive, which leads to a loss of output voltage. Increasing the value of C1 improves load regulation and reduces the charge-pump output resistance to an extent. See the Output Power vs. Load Resistance graph in the Typical Operating Characteristics. Above 1µF, the on-resistance of the switches and the ESR of C1 and C2 dominate. Hold Capacitor (C2) The hold capacitor value and ESR directly affect the ripple at PVSS. Increasing the value of C2 reduces output ripple. Likewise, decreasing the ESR of C2 reduces both ripple and output resistance. Lower capacitance values RIGHT AUDIO INPUT RIN INRRF Figure 7. Gain Setting for the MAX9722A can be used in systems with low maximum output power levels. See the Output Power vs. Load Resistance graph in the Typical Operating Characteristics. Power-Supply Bypass Capacitor The power-supply bypass capacitor (C3) lowers the output impedance of the power supply and reduces the impact of the MAX9722A/MAX9722Bs’ charge-pump switching transients. Bypass PVDD with C3, the same value as C1, and place it physically close to the PVDD and PGND pins. Amplifier Gain The gain of the MAX9722B is internally set at -2V/V. All gain-setting resistors are integrated into the device, reducing external component count. The internally set gain, in combination with DirectDrive, results in a headphone amplifier that requires only five tiny 1µF capacitors to complete the amplifier circuit: two for the charge pump, two for audio input coupling, and one for powersupply bypassing (see the Typical Application Circuit). The gain of the MAX9722A amplifier is set externally as shown in Figure 7, the gain is: AV = -RF/RIN Choose feedback resistor values of 10kΩ. Values other than 10kΩ increase output offset voltage due to the input bias current, which, in turn, increases the amount of DC current flow to the load. Table 1. Suggested Capacitor Manufacturers SUPPLIER Murata 770-436-1300 770-436-3030 WEBSITE www.murata.com Taiyo Yuden 800-348-2496 847-925-0899 www.t-yuden.com TDK 847-803-6100 847-390-4405 www.component.tdk.com 12 PHONE FAX ______________________________________________________________________________________ 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown MAX9722A LEFT AUDIO INPUT SHDN R1 RIGHT AUDIO INPUT R2 Common-Mode Noise Rejection Figure 9 shows a theoretical connection between two devices, for example, a notebook computer (transmitter, on the left) and an amplifier (receiver, on the right), Figure 8. Common-Mode Sense Input Eliminates Ground-Loop Noise EXAMPLE CONNECTION: VIN = VAUDIO VAUDIO GND NOISE COMPONENT IN OUTPUT = VNOISE/2 0.1Ω VNOISE 0.1Ω VREF_IN = VNOISE/2 • 0.10Ω RESISTANCE FROM CABLE SCREEN. • 0.10Ω RESISTANCE DUE TO GND CABLING AT RECEIVER. • VNOISE REPRESENTS THE POTENTIAL DIFFERENCE BETWEEN THE TWO GNDS. IMPROVEMENT FROM ADDING MAX9722 WITH SERIES RESISTANCE MAX9722A VIN = VAUDIO + (VNOISE x 0.98) VAUDIO GND NOISE COMPONENT IN OUTPUT = VNOISE /100 0.1Ω RESISTOR IS INSERTED BETWEEN THE JACK SLEEVE AND GND = 9.8Ω 9.8Ω VNOISE 0.1Ω VREF_IN = (VNOISE x 0.99) • 9.8Ω RESISTOR ADDS TO HP CROSSTALK, BUT DIFFERENTIAL SENSING AT THE JACK SLEEVE CORRECTS FOR THIS (ONE CHANNEL ONLY SHOWN). • CURRENT FLOW (IN SIGNAL CABLE SCREEN) DUE TO VNOISE IS GREATLY REDUCED. • NOISE COMPONENT IN THE RECEIVER OUTPUT IS REDUCED BY 34dB OVER THE PREVIOUS EXAMPLE WITH THE VALUES SHOWN. Figure 9. Common-Mode Noise Rejection ______________________________________________________________________________________ 13 MAX9722A/MAX9722B Common-Mode Sense When the headphone jack is used as a line out to interface between other equipment (notebooks, desktops, and stereo receivers), potential differences between the equipment grounds can create ground loops and excessive ground-current flow. The MAX9722A’s INR+ and INL+ inputs are connected together to form a common-mode input that senses and corrects for the difference between the headphone return and device ground (see Figure 8). Connect INR+ and INL+ through a resistive voltage-divider between the headphone jack return and SGND of the device. For optimum commonmode rejection, use the same value resistors for R1 and RF, and R2 and RIN. For the MAX9722B, RIN = 15kΩ and R F = 30kΩ. Improve DC CMRR by adding a capacitor between SGND and R 2 (see the Typical Application Circuit). If ground sensing is not required, connect INR+ and INL+ directly to SGND. It allows the MAX9722A/MAX9722B differential sensing to reduce the GND noise seen by the receiver (amplifier). The other side effect is that the differential headphone jack sensing corrects the headphone crosstalk (from introducing the resistance on the jack GND return). Only one channel is depicted in Figure 9. Figure 9 has some example numbers for resistance, but the audio designer has control over only one series resistance applied to the headphone jack return. Note that this resistance can be bypassed for ESD purposes at frequencies much higher than audio if required. The upper limit for this added resistance is the amount of output swing the headphone amplifier tolerates when driving low-impedance loads. Any headphone return current appears as a voltage across this resistor. Piezoelectric Speaker Amplifier Low-profile piezoelectric speakers can provide quality sound for portable electronics. However, piezoelectric speakers typically require large voltage swings (>8VP-P) across the speaker element to produce usable sound pressure levels. Power sources in portable devices are usually low voltage in nature. Operating from batteries, conventional amplifiers cannot provide sufficient voltage swing to drive a piezoelectric speaker. However, the MAX9722’s DirectDrive architecture can be configured to drive a piezoelectric speaker with up to 12VP-P while operating from a single 5V supply. The stereo MAX9722 features an inverting charge pump that takes the positive +5V supply and creates a negative -5V supply. Each output of the MAX9722 can swing 6VP-P. This may be sufficient to drive a piezoelectric speaker. If a higher output voltage is desired, configuring the MAX9722A as a bridge-tied load (BTL) amplifier (Figure 10) doubles the maximum output swing as seen by the load to 12VP-P. In a BTL configuration, the right channel of the MAX9722 serves as the master amplifier, setting the gain of the device, driving one side of the speaker, and providing signal to the left 14 10kΩ 1µF AUDIO INPUT 10kΩ INR OUTR 10kΩ INL 10kΩ OUTL MAX9722A Figure 10. MAX9722 BTL Configuration TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE 100 MAX9722 fig11 such as the headphone socket used as a line output to a home hi-fi system. In the upper diagram, any difference between the two GND references (represented by VNOISE) causes current to flow through the screen of cable between the two devices. This can cause noise pickup at the receiver due to the potential divider action of the audio screen cable impedance and the GND wiring of the amplifier. Introducing impedance between the jack socket and GND of the notebook helps (as shown in the lower diagram). This has the following effect: Current flow (from GND potential differences) in the cable screen is reduced, which is a safety issue. VDD = 5V AV = -1V/V OUTPUTS DRIVING PIEZOELECTRIC SPEAKER 10 1 THD+N (%) MAX9722A/MAX9722B 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown f = 1kHz 0.1000 0.0100 f = 20Hz 0.0010 f = 100Hz 0.0001 0 2 4 6 8 10 12 14 OUTPUT POWER (mW) Figure 11. MAX9722 THD+N vs. Output Voltage channel. The left channel is configured as a unity-gain follower, inverting the output of the right channel and driving the other leg of the speaker. Use precision resistors to set the gain of the left channel to ensure low distortion and good matching. The MAX9722 was tested with a Panasonic WM-R57A piezoelectric speaker, and the resulting THD+N curves are shown (Figures 11 and 12). Note in both graphs, as frequency increases, the THD+N increases. This is due ______________________________________________________________________________________ 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown MAX9722A/MAX9722B TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX9722 fig12 10 THD+N (%) VDD = 5V AV = -1V/V 1 VOUT(P-P) = 2V OUTPUTS DRIVING PIEZOELECTRIC SPEAKER A 0.1 500mV/div 0.01 0.001 4µs/div 0.0001 10 100 1k 10k 100k FREQUENCY (Hz) Figure 12. MAX9722 THD+N vs. Frequency B to the capacitive nature of the piezoelectric speaker, as frequency increases, the speaker impedance decreases, resulting in a larger current draw from the amplifier. Furthermore, the capacitive nature of the speaker can cause the MAX9722 to become unstable. In these tests, the MAX9722 exhibited instabilities when driving the WM-R57A. A simple inductor/resistor network in series with the speaker isolates the speaker’s capacitance from the amplifier, and ensures the device output sees a resistive load of about 10Ω at high frequency maintaining stability. Although the MAX9722 was not stable with the WM-R57A, a different speaker with different characteristics may result in stable operation, and elimination of the isolation components. Layout and Grounding Proper layout and grounding are essential for optimum performance. Connect PGND and SGND together at a single point on the PC board. Connect all components associated with the charge pump (C2 and C3) to the PGND plane. Connect PVDD and SVDD together at the device. Connect PVSS and SVSS together at the device. Bypassing of both supplies is accomplished by chargepump capacitors C2 and C3 (see the Typical Application Circuit). Place capacitors C2 and C3 as close to the device as possible. Route PGND and all traces that carry switching transients away from SGND and the traces and components in the audio signal path. Refer to the MAX9722 evaluation kit for layout guidelines. 500mV/div 2µs/div Figure 13. MAX9722 Capacitive-Load Stability Waveform: (a) Falling Edge, (b) Rising Edge 10kΩ AUDIO INPUT 1µF 10kΩ INR 10Ω OUTR 10kΩ 100µH INL 10kΩ OUTL MAX9722A Figure 14. Isolation Network Improves Stability ______________________________________________________________________________________ 15 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown MAX9722A/MAX9722B System Diagram VDD 0.1µF 15kΩ 0.1µF 15kΩ INR VDD PVDD 0.1µF 1µF OUTR- MAX9710 BIAS AUX_IN OUTR+ 1µF SHDN OUT OUTL- 0.1µF 15kΩ MAX4060 BIAS OUTL+ INL VDD 15kΩ CODEC VDD 2.2kΩ 10kΩ 0.1µF IN- IN+ VDD 10kΩ Q IN0.1µF MAX961 Q 100kΩ 100kΩ IN+ 0.1µF INL+ INR+ SHDN 1µF INL- MAX9722B OUTL 1µF VDD OUTR INR- PVSS 1µF PVDD SVDD SVSS C1P CIN 1µF 1µF The thin QFN package features an exposed paddle that improves thermal efficiency of the package. The MAX9722A/MAX9722B do not require additional 16 heatsinking. The exposed paddle can be either connected to PVSS or a small electrically isolated copper plane. Do not connect to PGND, SGND, PVDD, or SVDD. ______________________________________________________________________________________ 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown CIN 1µF 2.4V TO 5.5V LEFT CHANNEL AUDIO IN C3 1µF 1 (3) 9, 13 (11, 15) 16 (2) 14 (16) PVDD SVDD SHDN INL- RF* 30kΩ SVDD RIN* 15kΩ 12 OUTL (14) HEADPHONE JACK UVLO/ SHUTDOWN CONTROL 2 (4) C1P SVSS CHARGE PUMP C1 1µF CLICK-AND-POP SUPPRESSION 4 (6) C1N SVDD SGND OUTR RIN 15kΩ MAX9722A MAX9722B 10 (12) SVSS RF 30kΩ PVSS 5 (7) SVSS PGND 3 (5) 11 (13) SGND 6 (8) INR+ 7 (9) C2 1µF RIGHT CHANNEL AUDIO IN INR8 (10) CIN 1µF *FOR MAX9722A, RIN AND RF ARE EXTERNAL TO THE DEVICE. ( ) FOR TSSOP PACKAGE. ______________________________________________________________________________________ 17 MAX9722A/MAX9722B Typical Application Circuit 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown 3 C1N 4 C1N 6 11 SVDD PVSS 7 10 INR- SGND 8 9 INR+ TSSOP INL- SVDD 14 13 8 PGND 12 OUTR MAX9722A MAX9722B INR- PGND 5 13 SVSS 7 2 MAX9722A MAX9722B INR+ C1P C1P 4 INL+ 1 15 PVDD 14 OUTL 6 15 SVDD PVDD 3 SGND SHDN 2 SHDN 16 INL- 16 INL+ 1 5 TOP VIEW PVSS MAX9722A/MAX9722B Pin Configurations THIN QFN Chip Information TRANSISTOR COUNT: 1100 PROCESS: BiCMOS 18 ______________________________________________________________________________________ 12 OUTL 11 SVSS 10 OUTR 9 SVDD 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown TSSOP4.40mm.EPS PACKAGE OUTLINE, TSSOP 4.40mm BODY 21-0066 I 1 1 ______________________________________________________________________________________ 19 MAX9722A/MAX9722B 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.) 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.) (NE - 1) X e E MARKING 12x16L QFN THIN.EPS MAX9722A/MAX9722B 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown E/2 D2/2 (ND - 1) X e D/2 AAAA e CL D D2 k CL b 0.10 M C A B E2/2 L E2 0.10 C C L C L 0.08 C A A2 A1 L L e e PACKAGE OUTLINE 8, 12, 16L THIN QFN, 3x3x0.8mm 21-0136 20 ______________________________________________________________________________________ I 1 2 5V, Differential Input, DirectDrive, 130mW Stereo Headphone Amplifiers with Shutdown PKG 8L 3x3 12L 3x3 16L 3x3 REF. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. A 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 b 0.25 0.30 0.35 0.20 0.25 0.30 0.20 0.25 0.30 D 2.90 3.00 3.10 2.90 3.00 3.10 2.90 3.00 3.10 E 2.90 3.00 3.10 2.90 3.00 3.10 2.90 3.00 3.10 e L 0.65 BSC. 0.35 N 0.55 0.50 BSC. 0.75 0.45 0.55 0.50 BSC. 0.65 0.30 12 8 0.40 2 3 4 NE 2 3 4 0 A1 k 0.02 0.05 0 0.20 REF 0.25 - 0.02 0.05 0 0.20 REF - 0.25 0.50 16 ND A2 EXPOSED PAD VARIATIONS - - 0.02 0.05 0.20 REF 0.25 - PKG. CODES D2 MIN. NOM. E2 MAX. MIN. NOM. MAX. PIN ID JEDEC TQ833-1 0.25 0.70 1.25 0.25 0.70 1.25 0.35 x 45° WEEC T1233-1 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-1 T1233-3 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-1 T1233-4 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-1 T1633-2 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-2 T1633F-3 0.65 0.80 0.95 0.65 0.80 0.95 0.225 x 45° WEED-2 T1633FH-3 0.65 0.80 0.95 0.65 0.80 0.95 0.225 x 45° WEED-2 T1633-4 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-2 T1633-5 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-2 - NOTES: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. N IS THE TOTAL NUMBER OF TERMINALS. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm FROM TERMINAL TIP. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS . DRAWING CONFORMS TO JEDEC MO220 REVISION C. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY. WARPAGE NOT TO EXCEED 0.10mm. PACKAGE OUTLINE 8, 12, 16L THIN QFN, 3x3x0.8mm 21-0136 I 2 2 Revision History Pages changed at Rev 2: 1, 13, 16, 19, 20, 21 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 ____________________ 21 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX9722A/MAX9722B 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.)