MAXIM MAX9820

19-4666; Rev 0; 7/09
KIT
ATION
EVALU
LE
B
A
IL
A
AV
DirectDrive Headphone Amplifier
with External Gain
Vista®-compliant
The MAX9820 Windows
stereo headphone amplifier is designed for portable equipment
where board space is at a premium. It features Maxim’s
patented DirectDrive ® 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.
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 (32Ω, VDD = 5V)
o Low-Current Shutdown Mode, < 1µA
o Low 3mA (VDD = 3.3V) Quiescent Current
o Space-Saving, 3mm x 3mm, 10-Pin TDFN Package
Ordering Information
The MAX9820 is available in a 10-pin TDFN package
(3mm x 3mm x 0.8mm) and specified over the -40°C to
+85°C extended temperature range.
Applications
PART
TEMP RANGE
MAX9820ETB+ -40°C to +85°C
PINPACKAGE
TOP MARK
10 TDFN-EP*
AUU
+Denotes a lead(Pb)-free/RoHS-compliant package.
Cell Phones
*EP = Exposed pad.
MP3 Players
Notebook PCs
PDAs
Pin Configuration
Simplified Block Diagram
TOP VIEW
C1P
1
10
GND
C1N
2
9
SHDN
VSS
3
8
VDD
OUTL
4
7
INL
6
INR
OUTR
5
MAX9820
*EP
TDFN
MAX9820
LEFT
AUDIO
INPUT
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS
SHDN
RIGHT
AUDIO
INPUT
*EXPOSED PAD.
Windows Vista is a registered trademark of Microsoft Corp.
DirectDrive is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________ 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
MAX9820
General Description
MAX9820
DirectDrive Headphone Amplifier
with External Gain
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 = +70°C)
10-Pin TDFN Single-Layer PCB (derate 18.5mW/°C
above +70°C)........................................................1481.5mW
Junction-to-Case Thermal Resistance (θJC) (Note 1)
10-Pin TDFN ................................................................8.5°C/W
Junction-to-Ambient Thermal Resistance (θJA) (Note 1)
10-Pin TDFN ...............................................................41.0°C/W
Continuous Power Dissipation (TA = +70°C)
10-Pin TDFN Multilayer PCB (derate 24.4mW/°C
above +70°C)...........................................................1951mW
Junction-to-Case Thermal Resistance (θJC) (Note 1)
10-Pin TDFN .................................................................9.0°C/W
Junction-to-Ambient Thermal Resistance (θJA) (Note 1)
10-Pin TDFN ...............................................................41.0°C/W
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
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 = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞, TA = -40°C to +85°C,
unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
GENERAL
Supply Voltage Range
VDD
Undervoltage Lockout
UVLO
Guaranteed by PSRR test
2.7
2.2
V
VDD = 3.3V
3.0
4.6
VDD = 5V
4.0
6.0
VSHDN = 0V, TA = +25°C
< 0.1
1
Output Signal Attenuation in
Shutdown
VSHDN = 0V, VIN = 1VRMS, RLOAD = 10kΩ
-110
dBV
Output Impedance in
Shutdown
VSHDN = 0V
0.6
kΩ
Quiescent Current
IDD
Shutdown Current
ISHDN
Turn-On Time
tON
Output Offset Voltage
VOS
0.56
TA = +25°C (Note 3)
ZLOAD = 32Ω + 1µH, peak
voltage, A-weighted, 32 samples
per second (Notes 3, 4)
Click-and-Pop Level
KCP
ZLOAD = 10kΩ, peak voltage,
A-weighted, 32 samples per
second (Notes 3, 4)
2
±0.1
Into shutdown
-79
Out of
shutdown
-77
Into shutdown
-62
Out of
shutdown
-58
mA
µA
ms
±0.5
mV
dBV
_______________________________________________________________________________________
DirectDrive Headphone Amplifier
with External Gain
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞, TA = -40°C to +85°C,
unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
VDD = 2.7V to 5.5V, TA = +25°C (Note 3)
Power-Supply Rejection Ratio
PSRR
MIN
TYP
75
90
f = 1kHz, 200mVP-P (Note 3)
POUT
Total Harmonic Distortion
Plus Noise
Signal-to-Noise Ratio
Output Noise
THD+N
SNR
VNOISE
Crosstalk
Capacitive Load Drive
Oscillator Frequency
CL
fOSC
55
ZLOAD= 32Ω + 1µH, f = 1kHz,
THD+N = 1%
VDD = 3.6V
45
VDD = 5.0V
95
ZLOAD= 16Ω + 1µH, f = 1kHz,
THD+N = 1%
VDD = 3.6V
32
VDD = 5.0V
0.014
ZLOAD = 32Ω + 1µH, f = 1kHz, POUT = 20mW
0.005
ZLOAD = 10kΩ, f = 1kHz, VOUT = 1VRMS
0.001
ZLOAD = 32Ω + 1µH, POUT = 25mW, A-weighted
A-weighted (Note 3)
ZLOAD = 32Ω + 1µH
FS = 0.300VRMS,
VOUT = 30mVRMS
%
105
dB
9
µV
73
dB
ZLOAD = 10kΩ
FS = 0.707VRMS,
VOUT = 70.7mVRMS
73
No sustained oscillations
TA = +25°C
mW
75
ZLOAD = 16Ω + 1µH, f = 1kHz, POUT = 20mW
L to R, R to L,
BW = 20Hz to 15kHz
UNITS
dB
73
f = 20kHz, 200mVP-P (Note 3)
Output Power
MAX
200
300
500
pF
800
kHz
Thermal Shutdown
145
°C
Thermal Shutdown Hysteresis
15
°C
DIGITAL INPUT (SHDN)
Input Voltage High
VINH
Input Voltage Low
VINL
Input Leakage Current
ILEAKAGE
1.2
TA = +25°C
V
0.3
V
±1
µA
Note 2: All specifications are 100% tested at TA = +25°C; temperature limits are guaranteed by design.
Note 3: The amplifier inputs are AC-coupled to GND.
Note 4: Mode transitions are controlled by SHDN.
_______________________________________________________________________________________
3
MAX9820
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞. Typical values are at TA
= +25°C, unless otherwise noted.)
THD+N vs. OUTPUT POWER
THD+N vs. OUTPUT POWER
f = 100Hz
THD+N (%)
THD+N (%)
0.1
VDD = 5.0V
RLOAD = 32I
LLOAD = 1FH
1
f = 6kHz
f = 100Hz
f = 6kHz
0.1
f = 1kHz
0.01
MAX9820 toc02
VDD = 5.0V
RLOAD = 16I
LLOAD = 1FH
1
10
MAX9820 toc01
10
0.01
f = 1kHz
0.001
0.001
0.02
0.04
0.06
0.08
0.10
0.14
0.12
0
0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16
OUTPUT POWER (W)
OUTPUT POWER (W)
THD+N vs. OUTPUT POWER
THD+N vs. OUTPUT POWER
VDD = 3.6V
RLOAD = 16I
LLOAD = 1FH
1
VDD = 3.6V
RLOAD = 32I
LLOAD = 1FH
1
0.1
THD+N (%)
f = 100Hz
THD+N (%)
10
MAX9820 toc03
10
f = 6kHz
0.01
MAX9820 toc04
0
f = 100Hz
0.1
f = 6kHz
0.01
f = 1kHz
f = 1kHz
0.001
0.001
0.01
0.02
0.03
0.04
0.05
0.06
0
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
OUTPUT POWER (W)
OUTPUT POWER (W)
THD+N vs. FREQUENCY
THD+N vs. FREQUENCY
VDD = 5.0V
RLOAD = 16I
LLOAD = 1FH
VDD = 5.0V
RLOAD = 32I
LLOAD = 1FH
1
THD+N (%)
1
10
MAX9820 toc05
10
POUT = 60mW
0.1
0.1
POUT = 60mW
0.01
0.01
POUT = 20mW
POUT = 20mW
0.001
0.001
10
100
1000
FREQUENCY (Hz)
4
MAX9820 toc06
0
THD+N (%)
MAX9820
DirectDrive Headphone Amplifier
with External Gain
10,000
100,000
10
100
1000
10,000
FREQUENCY (Hz)
_______________________________________________________________________________________
100,000
DirectDrive Headphone Amplifier
with External Gain
THD+N vs. FREQUENCY
THD+N vs. FREQUENCY
THD+N (%)
THD+N (%)
VDD = 3.6V
RLOAD = 32I
LLOAD = 1FH
1
0.1
POUT = 20mW
MAX9820 toc08
VDD = 3.6V
RLOAD = 16I
LLOAD = 1FH
1
10
MAX9820 toc07
10
0.1
POUT = 30mW
0.01
0.01
POUT = 10mW
POUT = 10mW
0.001
0.001
100
1000
10,000
100,000
10
100
FREQUENCY (Hz)
VISTA THD+N vs. FREQUENCY
FS = 300mVRMS
VDD = 5.0V
RLOAD = 10kI
LLOAD = 1µH
VOUT = -3dBFS
-20
THD+N (dBFS)
-80
-40
-60
FS = 707mVRMS
-80
-100
-100
FS = 1VRMS
FS = 1VRMS
-120
-120
10
100
1000
100,000
10,000
10
100
FREQUENCY (Hz)
MAX9820 toc11
180
RLOAD = 16I
LLOAD = 1µH
RLOAD = 32I
LLOAD = 1µH
150
120
POUT (mW)
120
POUT (mW)
100,000
10,000
OUTPUT POWER vs. SUPPLY VOLTAGE
OUTPUT POWER vs. SUPPLY VOLTAGE
180
150
1000
FREQUENCY (Hz)
THD+N = 10%
90
MAX9820 toc12
THD+N (dBFS)
-60
100,000
0
MAX9820 toc09
VDD = 5.0V
RLOAD = 32I
LLOAD = 1FH
VOUT = -3dBFS
-40
10,000
VISTA THD+N vs. FREQUENCY
0
-20
1000
FREQUENCY (Hz)
MAX9820 toc10
10
THD+N = 10%
90
60
60
30
THD+N = 1%
30
THD+N = 1%
0
0
2.7
3.1
3.5
3.9
4.3
4.7
SUPPLY VOLTAGE (V)
5.1
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
MAX9820
Typical Operating Characteristics
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞. Typical values are at TA
= +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞. Typical values are at TA
= +25°C, unless otherwise noted.)
OUTPUT POWER vs. LOAD RESISTANCE
60
THD+N = 10%
POUT (mW)
90
60
45
30
THD+N = 1%
THD+N = 1%
15
0
0
1
10
1000
100
10
POWER DISSIPATION
vs. OUTPUT POWER
POWER DISSIPATION
vs. OUTPUT POWER
300
RLOAD = 32I
200
VDD = 3.6V
LLOAD = 1µH
350
POWER DISSIPATION (mW)
RLOAD = 16I
400
100
MAX9820 toc16
400
MAX9820 toc15
VDD = 5.0V
LLOAD = 1µH
1000
100
LOAD RESISTANCE (I)
600
500
1
LOAD RESISTANCE (I)
300
RLOAD = 16I
250
200
RLOAD = 32I
150
100
50
0
0
0
20
40
60
80
0
120
100
20
40
60
80
100
OUTPUT POWER PER CHANNEL (mW)
OUTPUT POWER PER CHANNEL (mW)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
POWER-SUPPLY REJECTION RATIO
vs. SUPPLY VOLTAGE
0
MAX9820 toc17
0
VRIPPLE = 200mVP-P
-20
120
MAX9820 toc18
POUT (mW)
VDD = 3.6V
LLOAD = 1µH
THD+N = 10%
30
POWER DISSIPATION (mW)
MAX9820 toc14
VDD = 5.0V
LLOAD = 1µH
120
OUTPUT POWER vs. LOAD RESISTANCE
75
MAX9820 toc13
150
VRIPPLE = 200mVP-P
f = 1kHz
-20
-60
PSRR (dB)
-40
PSRR (dB)
MAX9820
DirectDrive Headphone Amplifier
with External Gain
RIGHT CHANNEL
-40
-60
LEFT CHANNEL
-80
-80
-100
RIGHT CHANNEL
LEFT CHANNEL
-100
-120
10
100
1000
FREQUENCY (Hz)
6
10,000
100,000
2.7
3.1
3.5
3.9
4.3
4.7
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5.1
5.5
DirectDrive Headphone Amplifier
with External Gain
-80
-40
OUTPUT SPECTRUM
MAX9820 toc20
0
LEFT TO RIGHT
-60
-80
-100
-100
RIGHT TO LEFT
RIGHT TO LEFT
-120
-120
100
1000
100,000
10,000
-40
-60
-80
-100
-120
-140
10
f = 1kHz
RLOAD = 32I
LLOAD = 1µH
-20
OUTPUT MAGNITUDE (dBV)
LEFT TO RIGHT
-60
RLOAD = 1kI
LLOAD = 1µH
FS = 707mVRMS
VOUT = -20dBFS
-20
CROSSTALK (dB)
-40
-140
10
FREQUENCY (Hz)
100
1000
10,000
100,000
0
2
4
FREQUENCY (Hz)
6
10 12 14 16 18 20
8
FREQUENCY (kHz)
QUIESCENT CURRENT
vs. SUPPLY VOLTAGE
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
4.0
MAX9820 toc23
0.45
MAX9820 toc22
4.5
0.40
3.5
SHUTDOWN CURRENT (nA)
SUPPLY CURRENT (mA)
CROSSTALK (dB)
MAX9820 toc19
RLOAD = 32I
LLOAD = 1µH
FS = 300mVRMS
VOUT = -20dBFS
-20
VISTA CROSSTALK vs. FREQUENCY
0
MAX9820 toc21
VISTA CROSSTALK vs. FREQUENCY
0
3.0
2.5
2.0
1.5
1.0
0.5
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
SUPPLY VOLTAGE (V)
3.1
3.5
3.9
4.3
5.1
5.5
ENTERING SHUTDOWN
EXITING SHUTDOWN
MAX9820 toc25
MAX9820 toc24
100Fs/div
4.7
SUPPLY VOLTAGE (V)
SHDN
2V/div
SHDN
2V/div
OUT_
1V/div
OUT_
1V/div
100Fs/div
_______________________________________________________________________________________
7
MAX9820
Typical Operating Characteristics (continued)
(VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞. Typical values are at TA
= +25°C, unless otherwise noted.)
DirectDrive Headphone Amplifier
with External Gain
MAX9820
Pin Description
PIN
NAME
1
C1P
Flying Capacitor Positive Terminal. Connect a 1µF ceramic capacitor from C1P to C1N.
FUNCTION
2
C1N
Flying Capacitor Negative Terminal. Connect a 1µF ceramic capacitor from C1N to C1P.
3
VSS
Charge-Pump Output. Bypass with a 1µF capacitor to GND.
4
OUTL
Left-Channel Output
5
OUTR
Right-Channel Output
6
INR
Right-Channel Input
7
INL
Left-Channel Input
8
VDD
Positive Power-Supply Input. Bypass with a 10µF capacitor to GND.
9
SHDN
Active-Low Shutdown Input
10
GND
Signal Ground
—
EP
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
Analog Line Output
Jack (RL = 10kΩ,
FS = 0.707VRMS)
Analog Headphone
Out Jack (RL = 32Ω,
FS = 0.300VRMS)
REQUIREMENT
WINDOWS VISTA PREMIUM MOBILE
SPECIFICATIONS
MAX9820
TYPICAL PERFORMANCE
THD+N
≤ -65dB FS (100Hz, 20kHz)
-83dBFS (100Hz, 20kHz)
Dynamic range with signal
present
≤ -80dBV, A-weighted (20Hz, 20kHz)
-101dB A-weighted
(20Hz, 20kHz)
Line output crosstalk
≤ -50dB (20Hz, 15kHz)
-73dB (20Hz, 15kHz)
THD+N
≤ -45dB FS (100Hz, 20kHz)
-85dBFS (100Hz, 20kHz)
Dynamic range with signal
present
≤ -60dBV, A-weighted (20Hz, 20kHz)
-94dB A-weighted
(20Hz, 20kHz)
Headphone output crosstalk
≤ -50dB (20Hz, 15kHz)
-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
RF IMMUNITY vs. FREQUENCY
VDD
-20
VDD
RF IMMUNITY (dBV)
VDD/2
GND
MAX9820 fig02
0
-40
LEFT CHANNEL
-60
-80
CONVENTIONAL DRIVER OUTPUT WAVEFORMS
-100
VOUT
RIGHT CHANNEL
-120
0.8
VDD
1.35
1.90
2.45
3.00
FREQUENCY (GHz)
Figure 2. MAX9820 RF Susceptibility
GND
2VDD
Click-and-Pop Suppression
-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.
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.
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.
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.
_______________________________________________________________________________________
9
MAX9820
DirectDrive Headphone Amplifier
with External Gain
Shutdown
Undervoltage Lockout (UVLO)
The MAX9820 features a low-power shutdown mode
that reduces quiescent current consumption to less
than 1µA, 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 600Ω || RFB. The amplifiers and
charge pump are enabled once SHDN is driven high.
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
θJA
where TJ(MAX) is +150°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.
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 θJA, 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 145°C (typ), the thermal protection circuitry
disables the amplifier output stage. The amplifiers are
enabled once the junction temperature cools by
approximately 15°C.
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
2πRINCIN
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
10
SUPPLIER
PHONE
FAX
WEBSITE
Taiyo Yuden
800-348-2496
847-925-0899
www.t-yuden.com
TDK
847-803-6100
847-390-4405
www.component.tdk.com
Murata
770-436-1300
770-436-3030
www.murata.com
______________________________________________________________________________________
DirectDrive Headphone Amplifier
with External Gain
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.
R
A V = − FB (V/ V)
RIN
Choose feedback resistor values in the tens of kΩ
range.
Functional Diagram/Typical Operating Circuit
CIN
1.0µF
RIN
40.2kΩ
RFB
40.2kΩ
7
INL
TO VDD
ON
9
SHDN
UVLO/SHUTDOWN
CONTROL
OFF
2.7V TO 5.5V
HEADPHONE
JACK
VDD
C3
10µF
OUTR
-1
C1
1.0µF
4
TO VSS
CLICK-AND-POP
SUPPRESSION
8
OUTL
-1
1
C1P
2
C1N
5
CHARGE
PUMP
TO VDD
10
INR
VSS
GND
3
C2
1.0µF
CIN
1.0µF
RIN
40.2kΩ
6
RFB
40.2kΩ
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________
11
MAX9820
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:
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
10 TDFN-EP
T1033+1
21-0137
6, 8, &10L, DFN THIN.EPS
MAX9820
DirectDrive Headphone Amplifier
with External Gain
12
______________________________________________________________________________________
DirectDrive Headphone Amplifier
with External Gain
COMMON DIMENSIONS
PACKAGE VARIATIONS
SYMBOL
MIN.
MAX.
PKG. CODE
N
D2
E2
e
JEDEC SPEC
b
[(N/2)-1] x e
A
0.70
0.80
T633-2
6
1.50±0.10
2.30±0.10
0.95 BSC
MO229 / WEEA
0.40±0.05
1.90 REF
D
2.90
3.10
T833-2
8
1.50±0.10
2.30±0.10
0.65 BSC
MO229 / WEEC
0.30±0.05
1.95 REF
E
2.90
3.10
T833-3
8
1.50±0.10
2.30±0.10
0.65 BSC
MO229 / WEEC
0.30±0.05
1.95 REF
A1
0.00
0.05
T1033-1
10
1.50±0.10
2.30±0.10
0.50 BSC
MO229 / WEED-3
0.25±0.05
2.00 REF
L
0.20
0.40
T1033-2
10
1.50±0.10
2.30±0.10
0.50 BSC
MO229 / WEED-3
0.25±0.05
2.00 REF
k
0.25 MIN.
T1433-1
14
1.70±0.10
2.30±0.10
0.40 BSC
----
0.20±0.05
2.40 REF
A2
0.20 REF.
T1433-2
14
1.70±0.10
2.30±0.10
0.40 BSC
----
0.20±0.05
2.40 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
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX9820
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.