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19-4981; Rev 1; 3/10
TION KIT EVALUA BLE AVAILA
Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier
General 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. 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 patented 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. Low-output offset voltage provides very good click-andpop performance both into and out of shutdown. High signal-to-noise ratio maintains system fidelity. 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.
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 (5.6V 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
MAX97200
Ordering Information/ Selector Guide
PART MAX97200AEWC+ MAX97200BEWC+ GAIN (dB) 3 0 PINPACKAGE 12 WLP 12 WLP TOP MARK ABF ABG
Note: All devices operate over the -40C to +85C temperature range. +Denotes a lead(Pb)-free and RoHS-compliant package.
Typical Operating Circuit
MAX97200
LEFT AUDIO INPUT
Applications
Cellular Phones Smartphones MP3 Players VoIP Phones
DirectDrive is a registered trademark of Maxim Integrated Products, Inc. Dual Mode is a trademark of Maxim Integrated Products, Inc.
APPLICATIONS PROCESSOR
LEFT AUDIO OUTPUT
SHDN RIGHT AUDIO INPUT RIGHT AUDIO OUTPUT
CHARGE PUMP
_______________________________________________________________ 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.
Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier MAX97200
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 12-Bump WLP BJA .......................................................73NC/W 12-Bump WLP BCA ......................................................30NC/W Junction Temperature .....................................................+150NC Operating Temperature Range .......................... -40NC to +85NC Storage Temperature Range............................ -65NC to +150NC Bump Temperature (soldering) Reflow ...........................+230NC
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.
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
(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 POWER SUPPLY Supply Voltage Range UVLO Rising UVLO Falling Quiescent Supply Current Shutdown Current Turn-On Time CHARGE PUMP Oscillator Frequency Oscillator Frequency Oscillator Frequency fOSC1 fOSC2 fOSC3 VOUT = 0V, TA = +25NC VOUT = 0.2V, RL = J, fIN = 1kHz VOUT = 0.5V, RL = J, fIN = 1kHz VOUT = 0.2V, RL = J VOUT = 0.5V, RL = J Negative Output Voltage VPVSS VOUT = 0.2V, RL = J VOUT = 0.5V, RL = J RL = J, output voltage at which the charge pump switches modes, VOUT rising, transition from 1/8 to normal frequency RL = J, output voltage at which the charge pump switches modes, VOUT rising, transition from high-efficiency mode to high-power mode 78 83 665 500 PVIN/2 PVIN -PVIN/2 -PVIN QPVIN x 0.08 QPVIN x 0.24 V 88 kHz kHz kHz IDD ISHDN tON Inputs grounded, TA = +25NC, no load 16I load, inputs grounded, TA = +25NC VSHDN = 0V, TA = +25NC 1.36 PVIN Guaranteed by PSRR 1.62 1.80 1.48 1.46 1.15 1.16 0.2 .6 1 1.7 1.98 1.58 V V V mA FA ms SYMBOL CONDITIONS MIN TYP MAX UNITS
Positive Output Voltage
VPVDD
V
Output Voltage Threshold
VTH1
V
Output Voltage Threshold
VTH2
V
2
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Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier
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 tHOLD Charge-Pump Mode Transition Timeouts (Figure 2) tRISE AMPLIFIER Voltage Gain Maximum Output Voltage Channel-to-Channel Gain Matching Total Output Offset Voltage Input Resistance VOS RIN TA = +25NC MAX97200A MAX97200B VPVDD = 1.62V to 1.98V, TA = +25NC Power-Supply Rejection Ratio PSRR fIN = 217Hz 100mVP-P ripple fIN = 1kHz fIN = 20kHz RL = 10kI Output Power Line Output Voltage Total Harmonic Distortion Plus Noise Output Noise Signal-to-Noise Ratio POUT VLINE THD+N VN SNR THD+N = 1% RL = 10kI RL = 16I, POUT = 0.1mW, fIN = 1kHz (Note 3) RL = 16I, POUT = 10mW, fIN = 1kHz (Note 4) RL = 10kI, VOUT = 1V, fIN = 1kHz (Note 4) Inputs grounded, A-weighted, MAX97200B A-weighted, MAX97200B RL = 32I, peak voltage, A-weighted, 32 samples/second, MAX97200B Into shutdown Out of shutdown RL = 32I RL = 16I 6 7.2 62 AV MAX97200A MAX97200B RL = 10kI, THD+N = 1% RL = 10kI, THD+N = 10% 2.75 -0.17 2.92 0 1.295 1.44 Q0.1 Q0.1 10 12 83 96 94 61 0.16 34 45 1 0.02 0.003 0.008 5.6 105 80 dBV 68 69 200 dB pF FV dB % VRMS mW dB Q0.3 14 16.8 3.09 +0.17 dB VPK dB mV kI CONDITIONS Time it takes for the charge pump to transition from high-power mode to high-efficiency mode; RL = J Time it takes for the charge pump to transition from high-efficiency mode to highpower mode (90% of its value); RL = J MIN TYP 32 MAX UNITS ms
MAX97200
20
Fs
Click-and-Pop Level
VCP
Crosstalk Maximum Capacitive Load
XTALK
RL = 16I, 1kHz, POUT = 5mW
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Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier MAX97200
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 DIGITAL INPUT (SHDN) Input High Voltage Input Low Voltage Input Leakage Current VIH VIL IIH IIL VSHDN = 4V, TA = +25NC VSHDN = 1.8V, TA = +25NC VSHDN = 0V, TA = +25NC -1 -1 -1 1.4 0.4 +1 +1 +1 FA V V SYMBOL CONDITIONS MIN TYP MAX UNITS
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
MAX97200 toc01
THD+N vs. OUTPUT POWER
MAX97200 toc02
THD+N vs. OUTPUT VOLTAGE
RL = 10kI
MAX97200 toc03
100 10 THD+N (%) 1 0.1
RL = 16I
100 10 THD+N (%) 1 0.1 0.01
RL = 32I
100 10 THD+N (%) 1 0.1
fIN = 100Hz 0.01 0.001 0 10 20 30 40 fIN = 1kHz fIN = 6kHz 50 60 70 80 POUT (mW)
fIN = 100Hz fIN = 1kHz
fIN = 1kHz 0.01 fIN = 6kHz 0.001
fIN = 100Hz
0.001 0 10 20 30 POUT (mW) 40 50 60
fIN = 6kHz 0 0.5 1.0 1.5 2.0 2.5 VOUT (VRMS)
THD+N vs. FREQUENCY
MAX97200 toc04
THD+N vs. FREQUENCY
MAX97200 toc05
THD+N vs. FREQUENCY
RL = 10kI
MAX97200 toc06
10
RL = 16I
10
RL = 32I
10
1 THD+N (%)
1 THD+N (%)
1 THD+N (%)
0.1 POUT = 20mW POUT = 25mW
0.1 POUT = 20mW 0.01 POUT = 2mW 0.01 0.1 POUT = 25mW
0.1 VOUT = 0.868VRMS 0.01 VOUT = 0.316VRMS 0.01 0.1 1 FREQUENCY (kHz) 10 100 VOUT = 1.12VRMS
0.01
POUT = 2mW 0.001 0.01 0.1 1 FREQUENCY (kHz) 10 100 0.001
0.001 1 FREQUENCY (kHz) 10 100
4
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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.)
OUTPUT POWER vs. LOAD RESISTANCE
MAX97200 toc07
MAX97200
OUTPUT POWER vs. LOAD RESISTANCE AND CHARGE-PUMP CAPACITOR
MAX97200 toc08
POWER CONSUMPTION vs. OUTPUT POWER
140 POWER CONSUMPTON (mW) 120 100 80 60 40 20 0
MAX97200 toc09
80 70 OUTPUT POWER (mW) 60 50 40 30 20 10 0 1 10 100 1000
80 70 OUTPUT POWER (mW) 60 50 40 30 20 10
160
10% THD + N
C1 = C2 = C3 = 1F C1 = C2 = C3 = .47F C1 = C2 = C3 = 2.2F
1% THD + N
10,000
0 10 100 1000 10,000 LOAD RESISTANCE (I)
1
10 OUTPUT POWER (mW)
100
LOAD RESISTANCE (I)
POWER DISSIPATION vs. OUTPUT POWER
MAX97200 toc10
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX97200 toc11
SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
0.18 0.16 SUPPLY CURRENT (A) 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 RL = J
MAX97200 toc12
100 90 POWER DISSIPATION (mW) 80 70 60 50 40 30 20 10 0 1 10 OUTPUT POWER (mW) RL = 32I RL = 16I
1.20 1.15 SUPPLY CURRENT (mA) 1.10 1.05 1.00 0.95 0.90 0.85 0.80
RL = J
0.20
100
1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 SUPPLY VOLTAGE (V)
1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 SUPPLY VOLTAGE (V)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX97200 toc13
CROSSTALK vs. FREQUENCY
MAX97200 toc14
IN-BAND OUTPUT SPECTRUM
f = 1kHz -20 OUTPUT MAGNITUDE (dBV) -40 -60 -80 -100 -120 -140
MAX97200 toc15
0 -20 -40 PSRR (dB) -60 -80 -100 -120
VRIPPLE = 200mVP-P
0 -10 -20 CROSSTALK (dB) -30 -40 -50 -60 -70 -80
OUTPUT POWER = 22mW RL = 16I
0
0.01
0.1
1 FREQUENCY (kHz)
10
100
-90 0.01 0.1 1 FREQUENCY (kHz) 10 100
-160 0.01 0.1 1 FREQUENCY (Hz) 10 100
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Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier 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.)
SUPPLY MODE SWITCHING
RL = 16I PVDD OUTPUT
MAX97200 toc16
TURN-ON RESPONSE
MAX97200 toc17
PVSS
SHDN 20ms/div 400s/div
TURN-OFF RESPONSE
MAX97200 toc18
OUTPUT
SHDN 400s/div
6
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Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier
Pin Configuration
TOP VIEW
MAX97200 1 2 3 4
MAX97200
A
OUTR
PVSS
C1N
C1P
B
OUTL
SHDN
GND
PGND
C
INL
INR
PVDD
PVIN
WLP
Pin Description
BUMP A1 A2 A3 A4 B1 B2 B3 B4 C1 C2 C3 C4 NAME OUTR PVSS C1N C1P OUTL SHDN GND PGND INL INR PVDD PVIN Right Amplifier Output Negative Charge-Pump Output. Connect a 1FF capacitor between PVSS and PGND. Charge-Pump Flying Cap Negative Connection. Connect 1FF capacitor between C1N and C1P. Charge-Pump Flying Cap Positive Connection. Connect 1FF capacitor between C1P and C1N. Left Amplifier Output Active-Low Shutdown Signal Ground. Connect to PGND. Power Ground. Connect to GND. Left Audio Input Right Audio Input Positive Charge-Pump Output. Bypass to PGND with 1FF. Main Power-Supply Connection. Bypass to PGND with 10FF. FUNCTION
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7
Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier MAX97200
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 patented 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. 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
DirectDrive Headphone Amplifier
GND
2VDD
-VDD DirectDrive BIASING SCHEME
Figure 1. Traditional Amplifier vs. MAX97200 DirectDrive Output
8
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Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier
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. 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. The MAX97200's internal Class H amplifier uses a class AB output stage with multiple, discreet 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. 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. 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. 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.
MAX97200
Click-and-Pop Suppression
Class H Operation
Shutdown
VPVDD IN_
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:
VPVSS
10ms/div
Figure 2. Inverting and Split Mode Transitions
f- 3dB =
1 2RINCIN
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9
Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier
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. 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 1/4 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 () in meters is given by:
= c/f
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) -30 -40 -50 -60 -70 -80 -90 -100 1000 1500 2000 FREQUENCY (MHz) 2500 3000
MAX97200
RIGHT CHANNEL LEFT CHANNEL
RF Susceptibility
Figure 3. Headphone RF Immunity 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.
Layout and Grounding
where c = 3 x 108 m/s, and f is the RF frequency of interest. 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.
10
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Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier
Simplified Functional Diagram
PROCESS: BiCMOS
1.8V C4 10F PVIN C4
Chip Information
MAX97200
MAX97200
RFB PVDD
INL C1 RIN INR C2 RIN SHDN GND PVSS RFB CHARGE PUMP B4 PGND C3 PVDD A3 C1N C3 1F A4 C1P C1 1F
B1 OUTL
A1 OUTR
B2 B3
A2 PVSS C2 1F
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11
Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier MAX97200
Package Information
For the latest package outline information and land patterns, 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 12-Bump WLP PACKAGE CODE W121A1+1 DOCUMENT NO. 21-0449
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Low-Power, Low-Offset, Dual Mode, Class H DirectDrive Headphone Amplifier
Revision History
REVISION NUMBER 0 1 REVISION DATE 1/10 3/10 Initial release Removed shutdown current max value DESCRIPTION PAGES CHANGED -- 2
MAX97200
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
(c)
13
2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.

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