19-4981; Rev 2; 3/11 TION KIT EVALUA BLE AVAILA Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier The MAX97200 is a 45mW Class H headphone amplifier that runs from a single low 1.8V supply voltage and employs Maxim’s second-generation DirectDrive technology. The MAX97200 features a Dual ModeK internal charge pump to generate the power rails for the amplifier. The charge-pump output can be QPVIN/2 or QPVIN depending on the amplitude of the output signal. When the output voltage is low, the power-supply voltage is QPVIN/2. When the output signal demands larger output voltage, the charge pump switches modes so that a greater power-supply voltage is realized and more output power can be delivered to the load. Second-generation DirectDrive technology improves power consumption when compared to first-generation DirectDrive amplifiers. The MAX97200 can be powered from a regulated 1.8V and have similar power consumption to a traditional DirectDrive amplifier that is powered from 0.9V. Maxim’s DirectDrive architecture uses an inverting charge pump to derive a negative voltage supply. The headphone amplifier is powered between the positive supply and the generated negative rail. This scheme allows the audio output signal to be biased about ground, eliminating the need for large DC-blocking capacitors between the amplifier output and the headphone load. Features S Second-Generation DirectDrive Technology S Dynamic, Class H, Dual Mode Charge Pump S Low Voltage Operation, VPVIN = 1.8V S Low Quiescent Current, 1.15mA (typ) at VPVIN = 1.8V S Eliminates Large Output DC-Blocking Capacitors S Industry-Leading Click-and-Pop Performance S High-Fidelity, SNR 105dB (5.6µV Output Noise) S Output Power 34mW into 32I (THD+N 1%) S Output Power 45mW into 16I (THD+N 10%) S Tiny, 12-Bump, 1.27mm x 1.65mm (0.4mm Lead Pitch) WLP Package Ordering Information/ Selector Guide PART GAIN (dB) MAX97200AEWC+ 3 12 WLP ABF MAX97200BEWC+ 0 12 WLP ABG +Denotes a lead(Pb)-free and RoHS-compliant package. Typical Operating Circuit The MAX97200 is available in a tiny, 12-bump wafer level packaging (WLP 1.27mm x 1.65mm) with a small, 0.4mm lead pitch and specified over the -40NC to +85NC extended temperature range. MAX97200 LEFT AUDIO INPUT Applications Smartphones APPLICATIONS PROCESSOR LEFT AUDIO OUTPUT SHDN RIGHT AUDIO INPUT RIGHT AUDIO OUTPUT MP3 Players VoIP Phones TOP MARK Note: All devices operate over the -40°C to +85°C temperature range. Low-output offset voltage provides very good click-andpop performance both into and out of shutdown. High signal-to-noise ratio maintains system fidelity. Cellular Phones PINPACKAGE CHARGE PUMP DirectDrive is a registered trademark of Maxim Integrated Products, Inc. Dual Mode is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX97200 General Description MAX97200 Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier ABSOLUTE MAXIMUM RATINGS PVIN or PVDD to PGND........................................-0.3V to +2.2V GND to PGND.......................................................-0.3V to +0.3V PVSS to PGND......................................................-2.2V to +0.3V OUT_ and IN_ to GND.............. (PVSS - 0.2V) to (PVDD + 0.2V) C1P, C1N....................................................Cap connection only SHDN to GND..........................................................-0.3V to +4V Output Short-Circuit Current......................................Continuous Thermal Limits (Note 1) Multiple Layer PCB Continuous Power Dissipation (TA = +70NC) 12-Bump WLP (derate 13.7mW/NC above +70NC).....1095mW Junction Temperature..................................................+150NC Operating Temperature Range........................... -40NC to +85NC Storage Temperature Range............................. -65NC to +150NC Soldering Temperature (reflow).......................................+260NC 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 1) Junction-to-Ambient Thermal Resistance (BJA)...............73NC/W Junction-to-Case Thermal Resistance (BCA)...................30NC/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. ELECTRICAL CHARACTERISTICS (VPVIN = 1.8V, VPGND = VGND = 0V, VSHDN = 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 1.62 1.80 1.98 V 1.48 1.58 V POWER SUPPLY Supply Voltage Range PVIN Guaranteed by PSRR UVLO Rising UVLO Falling 1.36 1.46 V Inputs grounded, TA = +25NC, no load 1.15 16I load, inputs grounded, TA = +25NC 1.16 ISHDN tON VSHDN = 0V, TA = +25NC 0.2 Oscillator Frequency fOSC1 VOUT = 0V, TA = +25NC Oscillator Frequency fOSC2 VOUT = 0.2V, RL = J, fIN = 1kHz 665 kHz Oscillator Frequency fOSC3 VOUT = 0.5V, RL = J, fIN = 1kHz 500 kHz Positive Output Voltage VPVDD Quiescent Supply Current Shutdown Current Turn-On Time IDD 1.7 mA FA 0.6 1 ms 83 88 kHz CHARGE PUMP Negative Output Voltage Output Voltage Threshold VPVSS VTH1 78 VOUT = 0.2V, RL = J PVIN/2 VOUT = 0.5V, RL = J PVIN VOUT = 0.2V, RL = J -PVIN/2 VOUT = 0.5V, RL = J -PVIN RL = J, output voltage at which the charge pump switches modes, VOUT rising, transition from 1/8 to normal frequency QPVIN x 0.08 2 _______________________________________________________________________________________ V V V Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier (VPVIN = 1.8V, VPGND = VGND = 0V, VSHDN = 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC) (Note 2) PARAMETER Output Voltage Threshold SYMBOL CONDITIONS MIN TYP MAX UNITS VTH2 RL = J, output voltage at which the charge pump switches modes, VOUT rising, transition from high-efficiency mode to high-power mode QPVIN x 0.24 V tHOLD Time it takes for the charge pump to transition from high-power mode to high-efficiency mode; RL = J 32 ms tRISE Time it takes for the charge pump to transition from high-efficiency mode to highpower mode (90% of its value); RL = J 20 Fs Charge-Pump Mode Transition Timeouts (Figure 2) AMPLIFIER Voltage Gain AV Maximum Output Voltage MAX97200A 2.75 2.92 3.09 MAX97200B -0.17 0 +0.17 RL = 10kI, THD+N = 1% 1.295 RL = 10kI, THD+N = 10% 1.44 Channel-to-Channel Gain Matching VOS Input Resistance RIN TA = +25NC Q0.1 Output Power PSRR POUT Line Output Voltage Total Harmonic Distortion Plus Noise Output Noise VLINE THD+N VN Signal-to-Noise Ratio Click-and-Pop Level Crosstalk Q0.3 6 10 14 MAX97200B 7.2 12 16.8 62 83 100mVP-P ripple THD+N = 1% fIN = 217Hz 96 fIN = 1kHz 94 fIN = 20kHz 61 RL = 10kI 0.16 RL = 32I 34 RL = 16I 45 1 RL = 10kI RL = 16I, POUT = 0.1mW, fIN = 1kHz (Note 3) 0.02 RL = 16I, POUT = 10mW, fIN = 1kHz (Note 4) 0.003 RL = 10kI, VOUT = 1V, fIN = 1kHz (Note 4) 0.008 mV kI dB mW VRMS % Inputs grounded, A-weighted, MAX97200B 5.6 FV SNR A-weighted, MAX97200B 105 dB VCP RL = 32I, peak voltage, A-weighted, 32 samples/second, MAX97200B XTALK Maximum Capacitive Load dB MAX97200A VPVDD = 1.62V to 1.98V, TA = +25NC Power-Supply Rejection Ratio VPK Q0.1 Total Output Offset Voltage dB Into shutdown 80 Out of shutdown 68 dBV RL = 16I, 1kHz, POUT = 5mW 94 dB 200 pF _______________________________________________________________________________________ 3 MAX97200 ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VPVIN = 1.8V, VPGND = VGND = 0V, VSHDN = 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25NC) (Note 2) PARAMETER SYMBOL DIGITAL INPUT (SHDN) Input High Voltage VIH Input Low Voltage VIL CONDITIONS MIN TYP MAX UNITS 1.4 V 0.4 IIH Input Leakage Current IIL VSHDN = 4V, TA = +25NC -1 +1 VSHDN = 1.8V, TA = +25NC -1 +1 VSHDN = 0V, TA = +25NC -1 +1 V FA Note 2: All specifications are 100% tested at TA = +25NC. Temperature limits are guaranteed by design. Note 3: VPVDD = 0.9V, VPVSS = -0.9V. Note 4: VPVDD = 1.8V, VPVSS = -1.8V. Typical Operating Characteristics (VPVIN = 1.8V, VPGND = VGND = 0V, VSHDN = 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, both channels driven in phase, TA = +25NC, unless otherwise noted.) THD+N vs. OUTPUT POWER 1 0.1 fIN = 100Hz fIN = 100Hz 50 60 0.001 70 20 0.1 POUT = 20mW POUT = 25mW RL = 32I 0.1 POUT = 20mW POUT = 2mW 0.001 1 0 0.5 10 100 1.0 1.5 2.0 2.5 THD+N vs. FREQUENCY 0.01 0.001 FREQUENCY (kHz) 60 VOUT (VRMS) 1 THD+N (%) 1 0.1 50 THD+N vs. FREQUENCY 10 MAX97200 toc04 RL = 16I 0.01 40 10 MAX97200 toc05 THD+N vs. FREQUENCY 0.01 30 POUT (mW) POUT (mW) 10 fIN = 6kHz 0.001 10 0 80 MAX97200 toc06 40 0.01 RL = 10kI 1 THD+N (%) 30 fIN = 100Hz fIN = 6kHz fIN = 6kHz 0.001 20 0.1 fIN = 1kHz 0.01 fIN = 1kHz 10 1 fIN = 1kHz 0.01 0 RL = 10kI 10 THD+N (%) 0.1 RL = 32I 10 THD+N (%) 1 THD+N vs. OUTPUT VOLTAGE 100 MAX97200 toc03 MAX97200 toc01 RL = 16I 10 THD+N (%) 100 MAX97200 toc02 THD+N vs. OUTPUT POWER 100 THD+N (%) MAX97200 Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier 0.1 VOUT = 0.868VRMS VOUT = 1.12VRMS 0.01 POUT = 2mW 0.01 0.1 POUT = 25mW 0.001 1 FREQUENCY (kHz) 10 100 VOUT = 0.316VRMS 0.01 0.1 1 FREQUENCY (kHz) 4 _______________________________________________________________________________________ 10 100 Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier OUTPUT POWER vs. LOAD RESISTANCE 1% THD + N 20 C1 = C2 = C3 = .47µF 40 C1 = C2 = C3 = 2.2µF 30 10 100 1000 MAX97200 toc09 40 100 10 1000 10 1 10,000 100 POWER DISSIPATION vs. OUTPUT POWER SUPPLY CURRENT vs. SUPPLY VOLTAGE SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE 1.15 SUPPLY CURRENT (mA) 70 60 RL = 32I 30 20 1.10 1.05 1.00 0.95 0.90 10 0.85 0 0.80 10 1 RL = J 100 RL = J 0.18 0.16 SUPPLY CURRENT (µA) RL = 16I 0.20 MAX97200 toc11 MAX97200 toc10 1.20 MAX97200 toc12 OUTPUT POWER (mW) 80 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 OUTPUT POWER (mW) SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY CROSSTALK vs. FREQUENCY 5mW 16I CROSSTALK (dB) -40 -60 -80 -100 -120 0.1 1 FREQUENCY (kHz) 10 100 OUTPUT POWER = 5mW RL = 16I IN-BAND OUTPUT SPECTRUM 0 MAX97200 toc15 VRIPPLE = 200mVP-P 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 MAX97200 toc14 MAX97200 toc13 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 -20 0.01 60 LOAD RESISTANCE (I) 90 40 80 LOAD RESISTANCE (I) 100 50 100 0 0 10,000 120 20 f = 1kHz -20 OUTPUT MAGNITUDE (dBV) 1 POWER DISSIPATION (mW) 50 140 10 0 0 C1 = C2 = C3 = 1µF 20 10 PSRR (dB) 60 160 POWER CONSUMPTON (mW) 40 30 70 OUTPUT POWER (mW) 10% THD + N 50 MAX97200 toc08 70 OUTPUT POWER (mW) 80 MAX97200 toc07 80 60 POWER CONSUMPTION vs. OUTPUT POWER OUTPUT POWER vs. LOAD RESISTANCE AND CHARGE-PUMP CAPACITOR -40 -60 -80 -100 -120 -140 -160 -120 20 50 100 200 500 1k 2k FREQUENCY (Hz) 5k 10k 20k 0.01 0.1 1 10 100 FREQUENCY (Hz) _______________________________________________________________________________________ 5 MAX97200 Typical Operating Characteristics (continued) (VPVIN = 1.8V, VPGND = VGND = 0V, VSHDN = 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, both channels driven in phase, TA = +25NC, unless otherwise noted.) MAX97200 Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier Typical Operating Characteristics (continued) (VPVIN = 1.8V, VPGND = VGND = 0V, VSHDN = 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, both channels driven in phase, TA = +25NC, unless otherwise noted.) SUPPLY MODE SWITCHING TURN-ON RESPONSE MAX97200 toc16 MAX97200 toc17 RL = 16I PVDD OUTPUT PVSS SHDN 20ms/div 400µs/div TURN-OFF RESPONSE MAX97200 toc18 OUTPUT SHDN 400µs/div 6 _______________________________________________________________________________________ Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier TOP VIEW MAX97200 1 2 3 4 A OUTR PVSS C1N C1P B OUTL SHDN GND PGND C INL INR PVDD PVIN WLP Pin Description BUMP NAME A1 OUTR Right Amplifier Output FUNCTION A2 PVSS Negative Charge-Pump Output. Connect a 1FF capacitor between PVSS and PGND. A3 C1N Charge-Pump Flying Cap Negative Connection. Connect 1FF capacitor between C1N and C1P. A4 C1P Charge-Pump Flying Cap Positive Connection. Connect 1FF capacitor between C1P and C1N. B1 OUTL Left Amplifier Output B2 SHDN GND Active-Low Shutdown B3 B4 PGND Power Ground. Connect to GND. C1 INL Left Audio Input C2 INR Right Audio Input C3 PVDD Positive Charge-Pump Output. Bypass to PGND with 1FF. C4 PVIN Main Power-Supply Connection. Bypass to PGND with 10FF. Signal Ground. Connect to PGND. _______________________________________________________________________________________ 7 MAX97200 Pin Configuration MAX97200 Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier Detailed Description The MAX97200 is a 45mW Class H headphone amplifier that runs from a single low 1.8V supply voltage and employs Maxim’s second-generation DirectDrive technology. Maxim’s DirectDrive architecture uses an inverting charge pump to derive a negative voltage supply. The headphone amplifier is powered between the positive supply and the generated negative rail. This scheme allows the audio output signal to be biased about ground, eliminating the need for large DC blocking capacitors between the amplifier output and the headphone load. Second-generation DirectDrive technology improves power consumption when compared to first-generation DirectDrive amplifiers. The MAX97200 can be powered from a regulated 1.8V supply and have similar power consumption to a traditional DirectDrive amplifier that is powered from 0.9V. The MAX97200 features a dual-mode internal charge pump to generate the power rails for the DirectDrive amplifier. The charge-pump output can be QPVIN/2 or QPVIN depending on the amplitude of the output signal. When the output voltage is low the power-supply voltage is QPVIN/2. When the output signal demands larger output voltage, the charge pump switches modes so that a greater power-supply voltage is realized and more output power can be delivered to the load. DirectDrive Headphone Amplifier Traditional single-supply headphone amplifiers have outputs biased at a nominal DC voltage (typically half the supply). 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 headphone and headphone amplifier. Maxim’s second-generation DirectDrive architecture uses a charge pump to create an internal negative supply voltage. This allows the headphone outputs of the MAX97200 to be biased at GND while operating from a single supply (Figure 1). Without a DC component, there is no need for the large DC-blocking capacitors. Instead of two large (220FF typ) capacitors, the MAX97200 charge pump requires 3 small ceramic capacitors, conserving board space, reducing cost, and improving the frequency response of the headphone amplifier. VOUT VDD VDD / 2 VDD GND CONVENTIONAL DRIVER BIASING SCHEME VOUT +VDD GND 2VDD -VDD DirectDrive BIASING SCHEME Figure 1. Traditional Amplifier vs. MAX97200 DirectDrive Output 8 _______________________________________________________________________________________ Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier High-power mode is similar to Maxim’s traditional DirectDrive architecture and is best suited for loads that require high voltage swing. High-efficiency mode improves power consumption by reducing the powersupply voltage across the amplifier’s output stage by half. The reduced power-supply voltage is good for idle conditions or low-signal level conditions into a headphone. Class H Operation The MAX97200’s internal Class H amplifier uses a class AB output stage with multiple, discrete power supplies. This result’s in two power-supply differentials of 1.8V and 3.6V generated from a single 1.8V external supply. The PVIN/2 power-supply differential is used when the output voltage requirements are low, and the output is below VTH2 as seen in Figure 2. The higher supply differential is used when the output voltage exceeds the high threshold VTH2, maximizing output power and voltage swing. The transition time from high-efficiency mode to high-power mode occurs when the threshold is crossed. VPVDD IN_ VPVSS 10ms/div Figure 2. Inverting and Split Mode Transitions The switch from high-power mode to high-efficiency mode occurs 32ms (typ) after the threshold is crossed. Built-in hysteresis keeps the charge pump from erratic mode switching when the output voltage is near the high and low thresholds. Click-and-Pop Suppression In conventional single-supply audio amplifiers, the output-coupling capacitor contributes significantly to 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. This results in a DC shift across the capacitor, which appears as an audible transient at the speaker. Since the MAX97200 does not require output coupling capacitors, this problem does not arise. Additionally, the MAX97200 features extensive click-and-pop suppression that eliminates any audible transient sources internal to the device. Typically, the output of the device driving the MAX97200 has a DC bias of half the supply voltage. At startup, the input-coupling capacitor, CIN, is charged to the preamplifier’s DC bias voltage through the MAX97200 input resistor, RIN. This DC shift across the capacitor results in an audible click-and-pop. The MAX97200 precharges the input capacitors when power is applied to ensure that no audible clicks or pops are heard when SHDN is pulled high. Shutdown The MAX97200 features a 1FA, low-power shutdown mode that reduces quiescent current consumption and extends battery life. Shutdown is controlled by the SHDN input. Driving the SHDN input low disables the drive amplifiers and charge pump and sets the headphone amplifier output resistance to 100I. Applications Information Component Selection Input-Coupling Capacitor The input capacitor (CIN), in conjunction with the amplifier input resistance (RIN_), forms a highpass filter that removes the DC bias from the 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 2πRINCIN _______________________________________________________________________________________ 9 MAX97200 Dual Mode Charge Pump The MAX97200’s Dual Mode, charge pump outputs either QPVIN/2 in high-efficiency mode or QPVIN in highpower mode, resulting in a power-supply differential of 1.8V or 3.6V. The charge-pump mode changes based on the level of the output signal needed. When the output voltage is small, the voltage rails are reduced to minimize power consumption. When the output voltage is large, the voltage rails are increased to accommodate the larger output need. RIN is the amplifier’s input resistance value. Choose CIN such that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the amplifier’s low frequency. Capacitors with higher voltage coefficients, such as ceramics, result in increased distortion at low frequencies. Charge-Pump Capacitor Selection Use capacitors with an ESR less than 100mI 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. Flying Capacitor (C1) The value of the flying capacitor (C1) affects the load regulation and output resistance of the charge pump. 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. Connect a 1FF capacitor between C1P and C1N. Output Capacitors (C2, C3) The output capacitor value and ESR directly affect the ripple at PVSS. Increasing the value of C2 and C3 reduces output ripple. Likewise, decreasing the ESR of C2 and C3 reduces both ripple and output resistance. Lower capacitance values can be used in systems with low maximum output power levels. Connect a 1FF capacitor between PVDD and PGND. Connect a 1FF capacitor between PVSS and PGND. RF Susceptibility Improvements to both layout and component selection can decrease the MAX97200 susceptibility to RF noise and prevent RF signals from being demodulated into audible noise. Trace lengths should be kept below ¼ of the wavelength of the RF frequency of interest. Minimizing the trace lengths prevents the traces from functioning as antennas and coupling RF signals into the MAX97200. The wavelength (λ) in meters is given by: λ = c/f where c = 3 x interest. 108 m/s, and f is the RF frequency of Route audio signals to the middle layers of the PCB to allow the ground planes above and below to shield them from RF interference. Ideally, the top and bottom layers of the PCB should primarily be ground planes to create effective shielding. Additional RF immunity can also be obtained from relying on the self-resonant frequency of capacitors as it exhibits the frequency response similar to a notch filter. Depending on the manufacturer, 10pF to 20pF capacitors typically exhibit self resonance at RF frequencies. These capacitors when placed at the input pins can effectively shunt the RF noise at the inputs of the MAX97200. For these capacitors to be effective, provide a low-impedance, low-inductance path from the capacitors to the ground plane. Do not use microvias to connect to the ground plane as these vias do not conduct well at RF frequencies. Figure 3 shows headphone RF immunity with a well laid out PCB. HEADPHONE RF IMMUNITY vs. FREQUENCY 0 -10 -20 OUTPUT NOISE (dBV) MAX97200 Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier -30 -40 -50 -60 RIGHT CHANNEL -70 LEFT CHANNEL -80 -90 -100 1000 1500 2000 2500 3000 FREQUENCY (MHz) Figure 3. Headphone RF Immunity Layout and Grounding Proper layout and grounding are essential for optimum performance. Use large traces for the power-supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance, as well as route heat away from the device. Good grounding improves audio performance, minimizes crosstalk between channels, and prevents switching noise from coupling into the audio signal. Connect PGND and GND together at a single point on the PCB. Route PGND and all traces that carry switching transients away from GND, and the traces and components in the audio signal path. Connect C2 to the PGND plane. Place the charge-pump capacitors (C1, C2) as close as possible to the device. Bypass PVDD with a 1FF capacitor to PGND. Place the bypass capacitors as close as possible to the device. 10 ������������������������������������������������������������������������������������� Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier Chip Information PROCESS: BiCMOS 1.8V C4 10µF PVIN C4 MAX97200 RFB PVDD INL C1 B1 OUTL RIN INR C2 A1 OUTR RIN SHDN GND PVSS B2 RFB A2 PVSS CHARGE PUMP B3 B4 PGND C3 A3 PVDD C1N C3 1µF A4 C2 1µF C1P C1 1µF ______________________________________________________________________________________ 11 MAX97200 Simplified Functional Diagram MAX97200 Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier Package Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.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. 12 WLP W121A1+1 21-0449 Refer to Application Note 1891 12 ������������������������������������������������������������������������������������� Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier REVISION NUMBER REVISION DATE 0 1/10 Initial release — 1 3/10 Removed shutdown current max value 2 2 3/11 Corrected crosstalk data in TOC 14 5 DESCRIPTION PAGES CHANGED 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 © 2011 Maxim Integrated Products 13 Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX97200 Revision History