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19-4666; Rev 0; 7/09
KIT ATION EVALU E AILABL AV
DirectDrive Headphone Amplifier with External Gain
General Description Features
o Clickless/Popless Operation o High RF Noise Rejection o Windows Vista Premium Mobile Compliant o 2.7V to 5.5V Single-Supply Operation o 95mW Output Power (32, VDD = 5V) o Low-Current Shutdown Mode, < 1A o Low 3mA (VDD = 3.3V) Quiescent Current o Space-Saving, 3mm x 3mm, 10-Pin TDFN Package
MAX9820
The MAX9820 Windows stereo headphone amplifier is designed for portable equipment where board space is at a premium. It features Maxim's patented DirectDrive (R) architecture to produce a ground-referenced output from a single supply, eliminating the large output-coupling capacitors required by conventional single-supply headphone amplifiers. The MAX9820 features an undervoltage lockout that prevents over discharging of the battery during brownout conditions, click-and-pop suppression that eliminates audible transients on startup, a low-power shutdown mode, and thermal-overload and short-circuit protection. Additionally, the MAX9820 suppresses RF radiation received by input and supply traces acting as antennas and prevents the amplifier from demodulating the coupled noise. The MAX9820 is available in a 10-pin TDFN package (3mm x 3mm x 0.8mm) and specified over the -40C to +85C extended temperature range.
Vista(R)-compliant
Ordering Information
PART TEMP RANGE PINPACKAGE 10 TDFN-EP* TOP MARK AUU
Applications
Cell Phones MP3 Players Notebook PCs PDAs
MAX9820ETB+ -40C to +85C
+Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad.
Pin Configuration
TOP VIEW
Simplified Block Diagram
C1P C1N VSS OUTL OUTR
1 2 3 4 5 *EP
10 9
GND SHDN VDD INL INR
MAX9820
LEFT AUDIO INPUT
DirectDrive OUTPUTS ELIMINATE DC-BLOCKING CAPACITORS
MAX9820
8 7 6
SHDN
TDFN
*EXPOSED PAD.
RIGHT AUDIO INPUT
Windows Vista is a registered trademark of Microsoft Corp. DirectDrive is a registered 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.
DirectDrive Headphone Amplifier with External Gain MAX9820
ABSOLUTE MAXIMUM RATINGS
VDD to GND ..............................................................-0.3V to +6V C1P to GND................................................-0.3V to (VDD + 0.3V) C1N to GND ................................................(VSS - 0.3V) to +0.3V VSS to GND...............................................................-6V to +0.3V OUTR, OUTL to GND.............................................................3V SHDN to GND...........................................................-0.3V to +6V INR, INL to GND .........................................-0.3V to (VDD + 0.3V) OUTR, OUTL Short Circuit to GND, VDD ....................Continuous Short Circuit Between OUTL and OUTR ....................Continuous Continuous Input Current (Into All Other Pins) .................20mA Continuous Power Dissipation (TA = +70C) 10-Pin TDFN Single-Layer PCB (derate 18.5mW/C above +70C)........................................................1481.5mW Junction-to-Case Thermal Resistance (JC) (Note 1) 10-Pin TDFN ................................................................8.5C/W Junction-to-Ambient Thermal Resistance (JA) (Note 1) 10-Pin TDFN ...............................................................41.0C/W Continuous Power Dissipation (TA = +70C) 10-Pin TDFN Multilayer PCB (derate 24.4mW/C above +70C)...........................................................1951mW Junction-to-Case Thermal Resistance (JC) (Note 1) 10-Pin TDFN .................................................................9.0C/W Junction-to-Ambient Thermal Resistance (JA) (Note 1) 10-Pin TDFN ...............................................................41.0C/W Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Junction Temperature ......................................................+150C Lead Temperature (soldering, 10s) .................................+300C
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
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2k (gain = -1V/V), C1 = C2 = 1F, C3 = 10F, RLOAD = , TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C, unless otherwise noted.) (Note 2)
PARAMETER GENERAL Supply Voltage Range Undervoltage Lockout Quiescent Current Shutdown Current Output Signal Attenuation in Shutdown Output Impedance in Shutdown Turn-On Time Output Offset Voltage tON VOS TA = +25C (Note 3) ZLOAD = 32 + 1H, peak voltage, A-weighted, 32 samples per second (Notes 3, 4) Click-and-Pop Level KCP ZLOAD = 10k, peak voltage, A-weighted, 32 samples per second (Notes 3, 4) Into shutdown Out of shutdown Into shutdown Out of shutdown VDD UVLO IDD ISHDN VDD = 3.3V VDD = 5V VSHDN = 0V, TA = +25C VSHDN = 0V, VIN = 1VRMS, RLOAD = 10k VSHDN = 0V Guaranteed by PSRR test 2.7 2.2 3.0 4.0 < 0.1 -110 0.6 0.56 0.1 -79 -77 dBV -62 -58 0.5 4.6 6.0 1 5.5 V V mA A dBV k ms mV SYMBOL CONDITIONS MIN TYP MAX UNITS
2
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DirectDrive Headphone Amplifier with External Gain
ELECTRICAL CHARACTERISTICS (continued)
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2k (gain = -1V/V), C1 = C2 = 1F, C3 = 10F, RLOAD = , TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C, unless otherwise noted.) (Note 2)
PARAMETER Power-Supply Rejection Ratio SYMBOL PSRR CONDITIONS VDD = 2.7V to 5.5V, TA = +25C (Note 3) f = 1kHz, 200mVP-P (Note 3) f = 20kHz, 200mVP-P (Note 3) ZLOAD= 32 + 1H, f = 1kHz, THD+N = 1% Output Power POUT ZLOAD= 16 + 1H, f = 1kHz, THD+N = 1% VDD = 3.6V VDD = 5.0V VDD = 3.6V VDD = 5.0V MIN 75 TYP 90 73 55 45 95 32 75 0.014 0.005 0.001 105 9 ZLOAD = 32 + 1H FS = 0.300VRMS, VOUT = 30mVRMS ZLOAD = 10k FS = 0.707VRMS, VOUT = 70.7mVRMS 300 73 dB 73 200 500 145 15 VINH VINL ILEAKAGE TA = +25C 1.2 0.3 1 800 pF kHz C C V V A dB V % mW dB MAX UNITS
MAX9820
Total Harmonic Distortion Plus Noise Signal-to-Noise Ratio Output Noise
ZLOAD = 16 + 1H, f = 1kHz, POUT = 20mW THD+N SNR VNOISE ZLOAD = 32 + 1H, f = 1kHz, POUT = 20mW ZLOAD = 10k, f = 1kHz, VOUT = 1VRMS ZLOAD = 32 + 1H, POUT = 25mW, A-weighted A-weighted (Note 3)
Crosstalk
L to R, R to L, BW = 20Hz to 15kHz
Capacitive Load Drive Oscillator Frequency Thermal Shutdown Thermal Shutdown Hysteresis DIGITAL INPUT (SHDN) Input Voltage High Input Voltage Low Input Leakage Current
CL fOSC
No sustained oscillations TA = +25C
Note 2: All specifications are 100% tested at TA = +25C; temperature limits are guaranteed by design. Note 3: The amplifier inputs are AC-coupled to GND. Note 4: Mode transitions are controlled by SHDN.
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3
DirectDrive Headphone Amplifier with External Gain MAX9820
Typical Operating Characteristics
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2k (gain = -1V/V), C1 = C2 = 1F, C3 = 10F, RLOAD = . Typical values are at TA = +25C, unless otherwise noted.)
THD+N vs. OUTPUT POWER
MAX9820 toc01
THD+N vs. OUTPUT POWER
VDD = 5.0V RLOAD = 32I LLOAD = 1FH f = 100Hz 0.1 f = 6kHz
MAX9820 toc02
10 VDD = 5.0V RLOAD = 16I LLOAD = 1FH f = 6kHz 0.1 f = 100Hz
10
1 THD+N (%)
1 THD+N (%)
0.01
f = 1kHz
0.01 f = 1kHz
0.001 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 OUTPUT POWER (W)
0.001 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 OUTPUT POWER (W)
THD+N vs. OUTPUT POWER
MAX9820 toc03
THD+N vs. OUTPUT POWER
VDD = 3.6V RLOAD = 32I LLOAD = 1FH
MAX9820 toc04
10 VDD = 3.6V RLOAD = 16I LLOAD = 1FH f = 100Hz 0.1 f = 6kHz
10
1 THD+N (%)
1 THD+N (%)
0.1
f = 100Hz
f = 6kHz
0.01
f = 1kHz
0.01 f = 1kHz
0.001 0 0.01 0.02 0.03 0.04 0.05 0.06 OUTPUT POWER (W)
0.001 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 OUTPUT POWER (W)
THD+N vs. FREQUENCY
MAX9820 toc05
THD+N vs. FREQUENCY
VDD = 5.0V RLOAD = 32I LLOAD = 1FH
MAX9820 toc06
10 VDD = 5.0V RLOAD = 16I LLOAD = 1FH
10
1 THD+N (%)
1 THD+N (%)
0.1
POUT = 60mW
0.1 POUT = 60mW 0.01
0.01 POUT = 20mW 0.001 10 100 1000 FREQUENCY (Hz) 10,000 100,000
0.001 10
POUT = 20mW 100 1000 FREQUENCY (Hz) 10,000 100,000
4
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DirectDrive Headphone Amplifier with External Gain
Typical Operating Characteristics
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2k (gain = -1V/V), C1 = C2 = 1F, C3 = 10F, RLOAD = . Typical values are at TA = +25C, unless otherwise noted.)
THD+N vs. FREQUENCY
MAX9820 toc07
MAX9820
THD+N vs. FREQUENCY
VDD = 3.6V RLOAD = 32I LLOAD = 1FH
MAX9820 toc08
10 VDD = 3.6V RLOAD = 16I LLOAD = 1FH
10
1 THD+N (%)
1 THD+N (%)
0.1 POUT = 20mW 0.01 POUT = 10mW 0.001 10 100 1000 FREQUENCY (Hz) 10,000 100,000
0.1 POUT = 30mW 0.01 POUT = 10mW 0.001 10 100 1000 FREQUENCY (Hz) 10,000 100,000
VISTA THD+N vs. FREQUENCY
MAX9820 toc09
VISTA THD+N vs. FREQUENCY
VDD = 5.0V RLOAD = 10kI LLOAD = 1H VOUT = -3dBFS
MAX9820 toc10
0 -20 -40 -60 -80 -100 FS = 1VRMS -120 10 100 1000 FREQUENCY (Hz) 10,000 VDD = 5.0V RLOAD = 32I LLOAD = 1FH VOUT = -3dBFS
0 -20 -40 -60 FS = 707mVRMS -80 -100 FS = 1VRMS -120
THD+N (dBFS)
FS = 300mVRMS
100,000
THD+N (dBFS)
10
100
1000 FREQUENCY (Hz)
10,000
100,000
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX9820 toc11
OUTPUT POWER vs. SUPPLY VOLTAGE
RLOAD = 32I LLOAD = 1H
MAX9820 toc12
180 150 120 POUT (mW) THD+N = 10% 90 60 30 0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 RLOAD = 16I LLOAD = 1H
180 150 120 POUT (mW) 90 60 30 0 THD+N = 1%
THD+N = 10%
THD+N = 1%
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
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5
DirectDrive Headphone Amplifier with External Gain MAX9820
Typical Operating Characteristics (continued)
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2k (gain = -1V/V), C1 = C2 = 1F, C3 = 10F, RLOAD = . Typical values are at TA = +25C, unless otherwise noted.)
OUTPUT POWER vs. LOAD RESISTANCE
MAX9820 toc13
OUTPUT POWER vs. LOAD RESISTANCE
VDD = 3.6V LLOAD = 1H 60 THD+N = 10% POUT (mW) 45
MAX9820 toc14
150 VDD = 5.0V LLOAD = 1H 120 THD+N = 10%
75
POUT (mW)
90
60 THD+N = 1%
30 THD+N = 1% 15
30
0 1 10 100 1000 LOAD RESISTANCE (I)
0 1 10 100 1000 LOAD RESISTANCE (I)
POWER DISSIPATION vs. OUTPUT POWER
MAX9820 toc15
POWER DISSIPATION vs. OUTPUT POWER
350 POWER DISSIPATION (mW) 300 250 200 150 100 50 0 0 20 40 60 80 100 120 RLOAD = 32I VDD = 3.6V LLOAD = 1H RLOAD = 16I
MAX9820 toc16
600 500 POWER DISSIPATION (mW) 400 300 200 100 0 0 20 40 60 80 100 RLOAD = 32I VDD = 5.0V LLOAD = 1H RLOAD = 16I
400
120
OUTPUT POWER PER CHANNEL (mW)
OUTPUT POWER PER CHANNEL (mW)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX9820 toc17
POWER-SUPPLY REJECTION RATIO vs. SUPPLY VOLTAGE
VRIPPLE = 200mVP-P f = 1kHz -20
MAX9820 toc18
0 VRIPPLE = 200mVP-P -20 -40 PSRR (dB) -60 -80 -100 -120 10 100 1000 FREQUENCY (Hz) 10,000
0
RIGHT CHANNEL
PSRR (dB)
-40
-60 LEFT CHANNEL -80
LEFT CHANNEL -100 100,000 2.7 3.1 3.5
RIGHT CHANNEL
3.9
4.3
4.7
5.1
5.5
SUPPLY VOLTAGE (V)
6
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DirectDrive Headphone Amplifier with External Gain
Typical Operating Characteristics (continued)
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2k (gain = -1V/V), C1 = C2 = 1F, C3 = 10F, RLOAD = . Typical values are at TA = +25C, unless otherwise noted.)
VISTA CROSSTALK vs. FREQUENCY
MAX9820 toc19
MAX9820
VISTA CROSSTALK vs. FREQUENCY
MAX9820 toc20
OUTPUT SPECTRUM
-20 OUTPUT MAGNITUDE (dBV) -40 -60 -80 -100 -120 -140 f = 1kHz RLOAD = 32I LLOAD = 1H
MAX9820 toc21
0 -20 CROSSTALK (dB) -40 -60 -80 -100 -120 10 100 1000 FREQUENCY (Hz) 10,000 RIGHT TO LEFT RLOAD = 32I LLOAD = 1H FS = 300mVRMS VOUT = -20dBFS
0 -20 CROSSTALK (dB) -40 -60 -80 -100 -120 -140 RIGHT TO LEFT RLOAD = 1kI LLOAD = 1H FS = 707mVRMS VOUT = -20dBFS LEFT TO RIGHT
0
LEFT TO RIGHT
100,000
10
100
1000 FREQUENCY (Hz)
10,000
100,000
0
2
4
6
8
10 12 14 16 18 20
FREQUENCY (kHz)
QUIESCENT CURRENT vs. SUPPLY VOLTAGE
MAX9820 toc22
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
0.40 SHUTDOWN CURRENT (nA) 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0
MAX9820 toc23
4.5 4.0 SUPPLY CURRENT (mA) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 2.7 3.1 3.5 3.9 4.3 4.7 5.1
0.45
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
EXITING SHUTDOWN
MAX9820 toc24
ENTERING SHUTDOWN
MAX9820 toc25
SHDN 2V/div
SHDN 2V/div
OUT_ 1V/div
OUT_ 1V/div
100Fs/div
100Fs/div
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7
DirectDrive Headphone Amplifier with External Gain MAX9820
Pin Description
PIN 1 2 3 4 5 6 7 8 9 10 -- NAME C1P C1N VSS OUTL OUTR INR INL VDD SHDN GND EP FUNCTION Flying Capacitor Positive Terminal. Connect a 1F ceramic capacitor from C1P to C1N. Flying Capacitor Negative Terminal. Connect a 1F ceramic capacitor from C1N to C1P. Charge-Pump Output. Bypass with a 1F capacitor to GND. Left-Channel Output Right-Channel Output Right-Channel Input Left-Channel Input Positive Power-Supply Input. Bypass with a 10F capacitor to GND. Active-Low Shutdown Input Signal Ground Exposed Pad. Internally connected to GND. Connect to a large ground plane to maximize thermal performance. Not intended as an electrical connection point.
Detailed Description
The MAX9820 95mW stereo headphone amplifier features Maxim's patented DirectDrive architecture, eliminating the large output-coupling capacitors required by conventional single-supply headphone amplifiers. The device features low RF susceptibility, extensive clickand-pop suppression, undervoltage lockout (UVLO) and shutdown control. The MAX9820 also features thermal-overload and short-circuit protection. The MAX9820 is Windows Vista Premium Mobile compliant (Table 1).
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 headphone and headphone amplifier. Maxim's patented DirectDrive architecture uses a charge pump to create an internal negative supply voltage, allowing the MAX9820 outputs to be biased at
Table 1. Windows Vista Premium Mobile Specifications vs. MAX9820 Specifications
DEVICE TYPE REQUIREMENT THD+N Analog Line Output Jack (RL = 10k, FS = 0.707VRMS) Dynamic range with signal present Line output crosstalk THD+N Analog Headphone Out Jack (RL = 32, FS = 0.300VRMS) Dynamic range with signal present Headphone output crosstalk WINDOWS VISTA PREMIUM MOBILE SPECIFICATIONS -65dB FS (100Hz, 20kHz) -80dBV, A-weighted (20Hz, 20kHz) -50dB (20Hz, 15kHz) -45dB FS (100Hz, 20kHz) -60dBV, A-weighted (20Hz, 20kHz) -50dB (20Hz, 15kHz) MAX9820 TYPICAL PERFORMANCE -83dBFS (100Hz, 20kHz) -101dB A-weighted (20Hz, 20kHz) -73dB (20Hz, 15kHz) -85dBFS (100Hz, 20kHz) -94dB A-weighted (20Hz, 20kHz) -73dB (20Hz, 15kHz)
Note: THD+N, dynamic range, and crosstalk are measured in accordance with AES-17 audio measurements standards.
8
_______________________________________________________________________________________
DirectDrive Headphone Amplifier with External Gain MAX9820
VOUT
VDD/2
VDD
-20 RF IMMUNITY (dBV) -40 -60 -80 -100 -120 RIGHT CHANNEL 0.8 1.35 1.90 FREQUENCY (GHz) 2.45 LEFT CHANNEL
GND
CONVENTIONAL DRIVER OUTPUT WAVEFORMS VOUT
VDD
3.00
Figure 2. MAX9820 RF Susceptibility
GND 2VDD
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 DirectDrive biases the outputs at ground, this problem does not arise. Additionally, the MAX9820 features extensive click-and-pop suppression that eliminates any audible transient sources internal to the device.
-VDD
MAX9820 OUTPUT WAVEFORMS
Figure 1. Conventional Driver Output Waveform vs. MAX9820 Output Waveform
GND (Figure 1). With no DC component, there is no need for the large DC-blocking capacitors. The MAX9820 charge pump requires two small ceramic capacitors, conserving board space, reducing cost, and improving the frequency response of the headphone amplifier.
RF Susceptibility
Modern audio systems are often subject to RF radiation from sources such as wireless and cellular phone networks. Although the RF radiation is out of the audio band, many signals, GSM signals in particular, contain bursts or modulation at audible frequencies. Most analog amplifiers demodulate the low-frequency envelope, adding noise to the audio signal. The MAX9820 architecture addresses the RF susceptibility problem by rejecting RF noise and preventing it from coupling into the audio band.
Charge Pump
The MAX9820 features a low-noise charge pump. The 500kHz (typ) charge pump switching frequency is well beyond the audio range and does not interfere with audio signals.
_______________________________________________________________________________________
MAX9820 fig02
VDD
RF IMMUNITY vs. FREQUENCY
0
9
DirectDrive Headphone Amplifier with External Gain MAX9820
Shutdown
The MAX9820 features a low-power shutdown mode that reduces quiescent current consumption to less than 1A, extending battery life for portable applications. Drive SHDN low to disable the amplifiers and the charge pump. In shutdown mode, the amplifier output impedance is set to 600 || RFB. The amplifiers and charge pump are enabled once SHDN is driven high.
Undervoltage Lockout (UVLO)
The MAX9820 features a UVLO function that prevents the device from operating if the supply voltage falls below 2.2V (min). This feature ensures proper operation during brownout conditions and prevents deep battery discharge. Once the supply voltage reaches the minimum supply voltage range, the MAX9820 charge pump is turned on and the amplifiers are powered, provided that SHDN is high.
Applications Information
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 or can be calculated by the following equation: PDISSPKG(MAX) = TJ(MAX) - TA JA
Component Selection
Input-Coupling Capacitor 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 Functional Diagram/Typical Operating 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 2RINCIN
where TJ(MAX) is +150C, TA is the ambient temperature, and JA is the reciprocal of the derating factor in C/W as specified in the Absolute Maximum Ratings section. The MAX9820 has two power dissipation sources: a charge pump and the two output amplifiers. If power dissipation for a given application exceeds the maximum allowed package power dissipation, reduce VDD, increase load impedance, decrease the ambient temperature, or add heatsinking to the device. Large output, supply, and ground traces decrease JA, allowing more heat to be transferred from the package to the surrounding air. Thermal-overload protection limits total power dissipation in the MAX9820. When the junction temperature exceeds 145C (typ), the thermal protection circuitry disables the amplifier output stage. The amplifiers are enabled once the junction temperature cools by approximately 15C.
Choose the CIN such that f-3dB is well below the lowest frequency of interest. 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 ceramic capacitors with a low ESR for optimum performance. For optimal performance over the extended temperature range, select capacitors with an X7R or X5R dielectric. Table 2 lists suggested manufacturers.
Table 2. Suggested Capacitor Vendors
SUPPLIER Taiyo Yuden TDK Murata PHONE 800-348-2496 847-803-6100 770-436-1300 FAX 847-925-0899 847-390-4405 770-436-3030 WEBSITE www.t-yuden.com www.component.tdk.com www.murata.com
10
______________________________________________________________________________________
DirectDrive Headphone Amplifier with External Gain
Amplifier Gain
The gain of the MAX9820 is set externally using input and feedback resistors (see the Functional Diagram/ Typical Operating Circuit). The gain is: R A V = - FB (V/ V) RIN Choose feedback resistor values in the tens of k range.
Layout and Grounding
Proper layout and grounding are essential for optimum performance. Connect EP and GND together at a single point on the PCB. Ensure ground return resistance is minimized for optimum crosstalk performance. Place the power-supply bypass capacitor, the charge-pump hold capacitor, and the charge-pump flying capacitor as close as possible to the MAX9820. Route all traces that carry switching transients away from the audio signal path.
MAX9820
Functional Diagram/Typical Operating Circuit
CIN 1.0F RIN 40.2k RFB 40.2k
7 INL TO VDD ON OFF 9 SHDN UVLO/SHUTDOWN CONTROL -1 OUTL 4 HEADPHONE JACK TO VSS
2.7V TO 5.5V 8 C3 10F 1 C1 1.0F C1P CHARGE PUMP VDD
CLICK-AND-POP SUPPRESSION
-1
OUTR
5
2
C1N
TO VDD
GND 10 3
VSS C2 1.0F CIN 1.0F RIN 40.2k 6
INR RFB 40.2k
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________
11
DirectDrive Headphone Amplifier with External Gain MAX9820
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 10 TDFN-EP PACKAGE CODE T1033+1 DOCUMENT NO. 21-0137
6, 8, &10L, DFN THIN.EPS
12
______________________________________________________________________________________
DirectDrive Headphone Amplifier with External Gain
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
MAX9820
COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40
PACKAGE VARIATIONS PKG. CODE T633-2 T833-2 T833-3 T1033-1 T1033-2 T1433-1 T1433-2 N 6 8 8 10 10 14 14 D2 1.500.10 1.500.10 1.500.10 1.500.10 1.500.10 1.700.10 1.700.10 E2 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 e 0.95 BSC 0.65 BSC 0.65 BSC 0.50 BSC 0.50 BSC 0.40 BSC 0.40 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEC MO229 / WEEC MO229 / WEED-3 MO229 / WEED-3 ------b 0.400.05 0.300.05 0.300.05 0.250.05 0.250.05 0.200.05 0.200.05 [(N/2)-1] x e 1.90 REF 1.95 REF 1.95 REF 2.00 REF 2.00 REF 2.40 REF 2.40 REF
0.25 MIN. 0.20 REF.
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 ____________________ 13
(c) 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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