MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
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General Description
The MAX98309/MAX98310 mono 1.4W class AB audio
amplifiers offer low quiescent current while maintaining
excellent SNR and low 0.008% THD+N. These ICs fea-
ture excellent 90dB PSRR and state of the art click-and-
pop suppression.
The ICs are offered with an internally fixed 0dB, 3dB,
6dB, and 9dB gain (MAX98310) or an externally set gain
(MAX98309) through external resistors.
The MAX98309 feature a 10ms or 100ms pin-selectable
turn-on time, while the MAX98310 has a preset 5ms turn-
on time.
The MAX98309/MAX98310 are available in a (1.0mm x
1.0mm) 9-bump, 0.3mm pitch WLP, and are specified over
the extended -40NC to +85NC temperature range.
Applications
Cell Phones/Smartphones
Digital Cameras
GPS
Portable Media Players
e-Readers
Tablets
Benefits and Features
S Enhances System Performance
Differential Input Improves Noise Immunity
Industry-Leading Click-and-Pop Suppression
High 90dB PSRR (fIN = 217Hz)
S Smaller Solution Size
1mm x 1mm WLP Footprint
S Extends Battery Life
Low Quiescent Current
S Delivers Robust System Design
Thermal Overload Protection
Short-Circuit Protection
S 1.2mA Supply Current (VDD = 3.7V)
S 750mW into 8I (VDD = 3.7V)
S 2.5V to 5.5V Supply Operation
S Pin-Selectable, Internally-Fixed Gain (MAX98310)
S 1.8V Logic-Compatible SHDN Input
Simplified Block Diagram
19-5912; Rev 0; 6/11
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to www.maxim-ic.com/MAX98309.related.
EVALUATION KIT AVAILABLE
BIAS
IN-
IN+
OUT+
OUT-
CIN
RIN
RIN
RF
RF
RF
SHDN GND
CIN
VDD
GND
MAX98310
BIAS VDD
2.5V TO 5.5V
2.5V TO 5.5V
GAIN
BIAS
0.1µF 1µF
RF
BIAS
IN-
IN+
OUT+
OUT-
CIN
RIN
RIN
SHDN
CIN
VDD
GND
MAX98309
BIAS TON
BIAS
0.1µF 1µF
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.
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MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
VDD to GND ............................................................... -0.3V to 6V
SHDN to GND ........................................................... -0.3V to 6V
All Other Pins to GND ...............................-0.3V to (VDD + 0.3V)
Continuous Current
VDD, GND, OUT_ ....................................................... Q750mA
IN_, SHDN, BIAS, GAIN, TON ......................................... Q20mA
OUT_ Short Circuit to GND or VDD Duration ............Continuous
OUT+ to OUT- Short Circuit Duration .......................Continuous
Continuous Power Dissipation (TA = +70NC)
WLP (derate 11.9mW/NC above +70NC)......................848mW
Junction Temperature .....................................................+150NC
Operating Temperature Range .......................... -40NC to +85NC
Storage Temperature Range ............................ -65NC to +150NC
Soldering Temperature (reflow).......................................+260NC
ABSOLUTE MAXIMUM RATINGS
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(VDD = 3.7V, VGND = 0V, SHDN = VDD, GAIN = VDD (0dB), CBIAS = 0.1µF, CIN = 0.47µF, no load: RIN = RF = 10kI (MAX98309),
TA = TMIN to TMAX. Typical values are at TA = +25°C, unless otherwise noted.) (Note 2)
PACKAGE THERMAL CHARACTERISTICS (Note 1)
WLP
Junction-to-Ambient Thermal Resistance (BJA)......... 94°C/W
Junction-to-Case Thermal Resistance (BJC) ...............41°C/W
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage Range VDD Guaranteed by PSRR test 2.5 5.5 V
Undervoltage Lockout UVLO VDD falling 1.8 2.3 V
Quiescent Supply Current IVDD SHDN = VDD
VDD = 3.7V 1.2 mA
VDD = 5V 1.9 1.8
Shutdown Supply Current IVDD_SD VSHDN = 0V, TA = +25NC2 3 FA
Turn-On Time tON
MAX98309 shutdown to
full operation
TON = GND 10 22.8
ms
TON = VDD 100
MAX98310 shutdown to full operation 5.7 11.5
Gain AVMAX98310
GAIN = VDD -0.25 0 +0.25
dB
GAIN = GND 2.75 3 3.25
GAIN = unconnected 5.75 6 6.25
GAIN = BIAS 8.75 9 9.25
Gain Selection Threshold MAX98310
GAIN = VDD 0.80 x
VDD
V
GAIN = GND 0.05 x
VDD
GAIN = unconnected 0.16 x
VDD
0.24 x
VDD
GAIN = BIAS 0.35 x
VDD
0.69 x
VDD
����������������������������������������������������������������� Maxim Integrated Products 3
MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 3.7V, VGND = 0V, SHDN = VDD, GAIN = VDD (0dB), CBIAS = 0.1µF, CIN = 0.47µF, no load: RIN = RF = 10kI (MAX98309), TA
= TMIN to TMAX. Typical values are at TA = +25°C, unless otherwise noted.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Differential Input Resistance RINDIFF
MAX98309, SHDN = VDD 1000
kI
MAX98310
GAIN = 0dB 38.2
GAIN = 3dB 31.7
GAIN = 6dB 25.5
Input Bias Current IINBIAS MAX98309/MAX98310, SHDN = VDD Q1FA
Shutdown Input Bias Current IINBIAS_
SHDN
SHDN = GND, IN_ = VDD or IN_ = GND -5 +5 FA
Output Offset Voltage VOS TA = +25NC (Note 3) Q0.2 Q1mV
Click-and-Pop Level KCP
RL = 8I, 32 samples per
second, A-weighted,
TA = +25NC (Notes 3, 4)
Into shutdown -66
dBV
Out of shutdown -66
Common-Mode Bias Voltage VBIAS Voltage at BIAS 0.475
x VDD
0.5 x
VDD
0.525
x VDD V
Input Common-Mode Voltage
Range VCM Inferred from CMRR test 0.5 VDD -
0.6 V
Common-Mode Rejection Ratio CMRR MAX98310/MAX98310
Guaranteed over
input common-
mode voltage
range
-50 -76
dB
fIN = 1kHz,
RL = 8I + 33FH-62
Power-Supply Rejection Ratio PSRR
DC 2.5V to 5.5V 73 93
dB
VRIPPLE = 200mVP-P
(Note 3)
fIN = 217Hz 90
fIN = 1kHz 90
fIN = 10kHz 72
Output Power POUT
VDD = 3.7V, 1% THD+N RL = 8I + 68FH0.750
W
RL = 4I + 33FH1.2
VDD = 3.7V, 10% THD+N RL = 8I + 68FH0.9
RL = 4I + 33FH1.5
VDD = 5V, 1% THD+N
(Note 5)
RL = 8I + 68FH1.4
RL = 4I + 33FH,
thermally limited 2.1
VDD = 5V, 10% THD+N
(Note 5)
RL = 8I + 68FH1.7
RL = 4I + 33FH,
thermally limited 2.7
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MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 3.7V, VGND = 0V, SHDN = VDD, GAIN = VDD (0dB), CBIAS = 0.1µF, CIN = 0.47µF, no load: RIN = RF = 10kI (MAX98309),
TA = TMIN to TMAX. Typical values are at TA = +25°C, unless otherwise noted.) (Note 2)
Note 2: All specifications are 100% tested at TA = +25°C; temperature limits are guaranteed by design.
Note 3: Inputs AC-coupled to GND.
Note 4: Mode transitions controlled by SHDN.
Note 5: Thermally limited by package.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Total Harmonic Distortion Plus
Noise THD+N
fIN = 1kHz, BW = 22Hz to
22kHz
RL = 8I + 68FH,
POUT = 375mW 0.008
%
RL = 4I + 33FH,
POUT = 750mW 0.06 0.02
fIN = 6kHz, BW = 22Hz to
22kHz
RL = 8I + 68FH,
POUT = 375mW 0.01
Signal-to-Noise Ratio SNR A-weighted, VDD = 5V, POUT = 1.4W,
RL = 8I + 33FH110 dB
Output Noise Voltage VNA-weighted (Note 3) 9 FV
Overcurrent Protection
Threshold 2 A
Thermal-Protection Threshold +160 NC
Thermal-Protection Hysteresis 15 NC
Maximum Capacitive Load
Drive CLBridge-tied load capacitance 500 pF
LOGIC INPUT (SHDN, TON) (MAX98309)
Input Logic-High VIH 1.8V logic compliant 1.4 V
Input Logic-Low VIL 1.8V logic compliant 0.4 V
Input Leakage Current High IIH TA = +25NC1FA
Input Leakage Current Low IIL TA = +25NC1FA
����������������������������������������������������������������� Maxim Integrated Products 5
MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
Typical Operating Characteristics
(VDD = 3.7V, VGND = 0V, SHDN = VDD, GAIN = GND (RF = RIN = 10kI), CBIAS = 0.1µF, CIN = 1µF, no load, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX98309 toc01
FREQUENCY (kHz)
THD+N (%)
10k1k100
0.01
0.1
1
10
0.001
10 100k
VDD = 4.2V
RL = 4I
POUT = 300mW
POUT = 50mW
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX98309 toc02
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.01
0.1
1
10
100
0.001
10 100k
VDD = 5V
RL = 8I
POUT = 200mW
POUT = 1.2W
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX98309 toc03
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.01
0.1
1
10
100
0.001
10 100k
VDD = 3.7V
RL = 4I
POUT = 800mW
POUT = 50mW
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX98309 toc04
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.01
0.1
1
10
100
0.001
10 100k
VDD = 3.7V
RL = 8I
POUT = 50mW POUT = 500mW
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX98309 toc06
OUTPUT POWER (mW)
THD+N (%)
150012501000750500250
0.01
0.1
1
10
100
0.001
0 1750
VDD = 5V
RL = 8I
fIN = 6kHz
fIN = 300Hz
fIN = 1kHz
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX98309 toc05
OUTPUT POWER (mW)
THD+N (%)
15001000500
0.01
0.1
1
10
100
0.001
0 2000
VDD = 4.2V
RL = 4I
fIN = 6kHz
fIN = 300Hz
fIN = 1kHz
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX98309 toc07
OUTPUT POWER (mW)
THD+N (%)
1200800400
0.01
0.1
1
10
100
0.001
0 1600
VDD = 3.7V
RL = 4I
fIN = 6kHz
fIN = 300Hz
fIN = 1kHz
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX98309 toc08
OUTPUT POWER (mW)
THD+N (%)
800600400200
0.01
0.1
1
10
100
0.001
0 1000
VDD = 3.7V
RL = 8I
fIN = 6kHz
fIN = 300Hz
fIN = 1kHz
����������������������������������������������������������������� Maxim Integrated Products 6
MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
Typical Operating Characteristics (continued)
(VDD = 3.7V, VGND = 0V, SHDN = VDD, GAIN = GND (RF = RIN = 10kI), CBIAS = 0.1µF, CIN = 1µF, no load, unless otherwise noted.)
OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
MAX98309 toc09
COMMON-MODE VOLTAGE (V)
VOS (mV)
4321
-4
-3
-2
-1
0
1
2
3
4
5
-5
0 5
VDD = 5V
RL = 8I
OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
MAX98309 toc10
COMMON-MODE VOLTAGE (V)
VOS (mV)
3.02.50.5 1.0 1.5 2.0
-3
-2
-1
0
1
2
3
4
-4
0 3.5
VDD = 3.7V
RL = 8I
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX98309 toc11
SUPPLY VOLATGE (V)
OUTPUT POWER (mW)
5.04.54.03.53.0
500
1000
1500
2000
2500
0
2.5 5.5
fIN = 1kHz
RL = 8I
THD+N = 10%
THD+N = 10%
LOAD RESISTANCE (I)
OUTPUT POWER (W)
100101 1k
OUTPUT POWER vs. LOAD
MAX98309 toc13
0.5
1.0
1.5
2.0
2.5
3.0
0
THD+N = 1%
THD+N = 10%
THERMALLY
LIMITED
VDD = 5V
fIN = 1kHz
ZLOAD = LOAD + 68µH
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX98309 toc12
SUPPLY VOLATGE (V)
OUTPUT POWER (mW)
5.04.54.03.53.0
500
1000
1500
2000
2500
THD+N = 10%
THD+N = 1%
THERMALLY
LIMITED
3000
3500
0
2.5 5.5
fIN = 1kHz
RL = 4I
OUTPUT POWER vs. LOAD
MAX98309 toc14
LOAD RESISTANCE (I)
OUTPUT POWER (mW)
10010
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0
1 1k
VDD = 3.7V
fIN = 1kHz
ZLOAD = LOAD + 68µH
THD+N = 10%
THD+N = 1%
����������������������������������������������������������������� Maxim Integrated Products 7
MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
Typical Operating Characteristics (continued)
(VDD = 3.7V, VGND = 0V, SHDN = VDD, GAIN = GND (RF = RIN = 10kI), CBIAS = 0.1µF, CIN = 1µF, no load, unless otherwise noted.)
POWER DISSIPATION
vs. OUTPUT POWER
MAX98309 toc15
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
15001000500
200
400
600
RL = 4I
800
1000
1200
1400
0
0 2000
VDD = 5V
fIN = 1kHz
POUT = POUTL + POUTR
RL = 8I
POWER DISSIPATION
vs. OUTPUT POWER
MAX98309 toc16
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
1200900300 600
100
200
300
400
600
500
RL = 4I
RL = 8I
700
800
0
0 1500
VDD = 3.7V
fIN = 1kHz
POUT = POUTL + POUTR
GAIN vs. FREQUENCY
(MAX98310)
MAX98309 toc17
FREQUENCY (Hz)
GAIN (dB)
10k1k100
-1
0
1
2
3
4
5
6
7
8
9
10
11
12
-2
-3
-4
-5
10 100k 1000k
AV = 9dB
AV = 6dB
AV = 3dB
AV = 0dB
PSRR vs. FREQUENCY
(MAX98309)
MAX98309 toc18
FREQUENCY (Hz)
PSRR (dB)
10k1k100
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-140
10 100k
RL = 8I
VRIPPLE = 200mV
VDD = 5V
VDD = 3.7V
CMRR vs. FREQUENCY
(MAX98309)
MAX98309 toc20
FREQUENCY (Hz)
CMRR (dB)
10k1k100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
10 100k
RL = 8I
THD + N = 1%
VDD = 3.7V
VDD = 5V
PSRR vs. FREQUENCY
(MAX98310)
MAX98309 toc19
FREQUENCY (Hz)
PSRR (dB)
10k1k100
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-120
10 100k
RL = 8I
VRIPPLE = 200mV
VDD = 3.7V
VDD = 5V
CMRR vs. FREQUENCY
(MAX98310)
MAX98309 toc21
FREQUENCY (Hz)
CMRR (dB)
10k1k100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
-100
10 100k
RL = 8I
THD + N = 1%
VDD = 3.7V
VDD = 5V
����������������������������������������������������������������� Maxim Integrated Products 8
MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
Typical Operating Characteristics (continued)
(VDD = 3.7V, VGND = 0V, SHDN = VDD, GAIN = GND (RF = RIN = 10kI), CBIAS = 0.1µF, CIN = 1µF, no load, unless otherwise noted.)
TURN-ON TIME (MAX98309) 10ms
MAX98309 toc22
2ms/div
TURN-ON TIME (MAX98309) 100ms
MAX98309 toc23
20ms/div
TURN-ON TIME MAX98310
MAX98309 toc24
1ms/div
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX98309 toc25
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5.04.54.03.53.0
0.5
1.0
1.5
2.0
2.5
3.0
0
2.5 5.5
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
MAX98309 toc27
SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT (µA)
5.04.54.03.53.0
1
2
3
4
5
6
7
8
9
0
2.5 5.5
SUPPLY CURRENT vs. TEMPERATURE
MAX98309 toc26
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
603510-15
0.5
1.0
1.5
2.0
2.5
0
-40 85
VDD = 5V
VDD = 3.7V
SHUTDOWN CURRENT
vs. TEMPERATURE
MAX98309 toc28
TEMPERATURE (°C)
SHUTDOWN CURRENT (µA)
603510-15
1
2
3
4
5
6
7
8
9
10
0
-40 85
VDD = 3.7V
VDD = 5V
����������������������������������������������������������������� Maxim Integrated Products 9
MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
Pin Descriptions
Pin Configurations
PIN NAME FUNCTION
MAX98309 MAX98310
A1 A1 OUT+ Amplifier Positive Output
A2 A2 SHDN Active-Low Shutdown Input. Connect to GND to place the IC into shutdown. Connect
to VDD for normal operation.
A3 A3 IN- Inverting Audio Input
B1 B1 GND Ground
B2 — TON Turn-On Time Selection. Connect TON to GND for a 10ms turn-on time. Connect TON
to VDD for a 100ms turn on time.
— B2 GAIN Gain Select Input. See Table 1 for gain settings.
B3 B3 VDD Power Supply Input. Connect a 1FF capacitor from VDD to GND.
C1 C1 OUT- Amplifier Negative Output
C2 C2 BIAS Common-Mode DC Bias Bypass. Connect a 0.1FF (min) capacitor to GND.
C3 C3 IN+ Noninverting Audio Input
WLP
TOP VIEW
(BUMP SIDE DOWN) MAX98309
1
+
2 3
B
C
AOUT+ SHDN IN-
GND
OUT- BIAS
TON VDD
IN+
WLP
TOP VIEW
(BUMP SIDE DOWN) MAX98310
1
+
2 3
B
C
AOUT+ SHDN IN-
GND
OUT- BIAS
GAIN VDD
IN+
���������������������������������������������������������������� Maxim Integrated Products 10
MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
Detailed Description
The MAX98309/MAX98310 mono 1.4W Class AB audio
amplifiers offer low quiescent current while maintaining
excellent SNR and low 0.008% THD+N. Both ICs feature
excellent 90dB PSRR and state-of-the-art click-and-pop
suppression.
The ICs are offered with an internally fixed 0dB, 3dB,
6dB, and 9dB gain (MAX98310) or an externally set gain
(MAX98309) through external resistors.
The MAX98309 features a 10ms or 100ms pin-selectable
turn-on time, while the MAX98310 has a preset 5ms turn-
on time.
Bias
The ICs operate from a single 2.5V to 5.5V power supply
and feature an internally generated common-mode bias
voltage of VDD/2 reference to ground. BIAS provides both
click-and-pop suppression and sets the DC bias level
for the audio outputs. Choose the value of the bypass
capacitor as described in the BIAS Capacitor section. Do
not connect external loads to BIAS as this can affect the
overall performance.
Turn-On Time
The MAX98309 external gain amplifier features a select-
able turn-on time for optimized click-and-pop perfor-
mance. Connect TON to GND for a 10ms turn-on time.
Connect TON to VDD for a 100ms turn-on time. The
MAX98310 has a preset 5ms turn-on time.
Shutdown Mode
The ICs feature a 1.8FA low-power shutdown mode
that reduces quiescent current consumption. When the
active-low shutdown mode is entered, the ICs’ internal
bias circuitry is disabled, the amplifier outputs go high
impedance, and BIAS is driven to GND.
Click-and-Pop Suppression
The ICs feature Maxim’s industry-leading click-and-
pop suppression circuitry. During startup, the amplifier
common-mode bias voltage ramps to the DC bias point.
When entering shutdown, the amplifier outputs are high
impedance between both outputs. This scheme mini-
mizes the energy present in the audio band.
Applications Information
BTL Amplifier
The ICs are designed to drive a load differentially, a
configuration referred to as bridge-tied load, or BTL. The
BTL configuration (Figure 1) offers advantages over the
single-ended configuration, where one side of the load
is connected to ground. Driving the load differentially
doubles the output voltage compared to a single-ended
amplifier under similar conditions.
Substituting 2 x VOUT(P-P) for VOUT(P-P) into the following
equations yields four times the output power due to
doubling of the output voltage:
OUT (P P)
RMS
RMS
OUT L
V
V2 2
V 2
PR
−
=
=
Because the differential outputs are biased at midsupply,
there is no net DC voltage across the load. This elimi-
nates the need for DC-blocking capacitors required for
single-ended amplifiers. These capacitors can be large,
expensive, consume board space, and degrade low-
frequency performance.
Power Dissipation and Heatsinking
Under normal operating conditions, the ICs dissipate a
significant amount of power. The maximum power dissi-
pation is given in the Absolute Maximum Ratings or can
be calculated by the following equation:
J(MAX) A
D(MAX) JA
T T
P
−
=
θ
where TJ(MAX) is +150NC, TA is the ambient temperature,
and BJA is the reciprocal of the derating factor in C/W as
specified in the Absolute Maximum Ratings.
Figure 1. BTL Configuration
+1 VOUT(P-P)
VOUT(P-P)
2 x VOUT(P-P)
-1
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MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
The increase in power delivered by the BTL configuration
directly results in an increase in internal power dissipa-
tion over the single-ended configuration. The maximum
internal power dissipation for a given VDD and load is
given by the following equation:
2
DD
D(MAX) 2L
2V
P
R
=
π
If the internal power dissipation for a given application
exceeds the maximum allowed for a given package,
reduce power dissipation by increasing the ground plane
heatsinking capability and the size of the traces to the
device. See the Layout and Grounding section. Other
methods for reducing power dissipation are to reduce
VDD, increase load impedance, decrease ambient
temperature, reduce gain, or reduce input signal.
Thermal-overload protection limits total power dissipation
in the MAX98309/MAX98310. When the junction temper-
ature exceeds +160NC, the thermal protection circuitry
disables the amplifier. Operation returns to normal once
the die cools by 15NC.
Amplifier Gain
Fixed Differential Gain (MAX98310)
The MAX98310 features four internally fixed differential
gain options selectable by GAIN (Table 1). This simplifies
design, decreases required application footprint size, and
eliminates external gain-setting resistors.
External Differential Gain (MAX98309)
The MAX98309 features an external gain option. Resistors
RF and RIN. See the Simplified Block Diagram and set the
gain of the amplifier as follows:
F
VIN
R
AR
=
where AV is the desired voltage gain. Hence, an RIN of
10kI and an RF of 20kI yields a gain of 2V/V or 6dB.
RF can be either fixed or variable, allowing the use of a
digitally controlled potentiometer to alter the gain under
software control.
Input Filter
The fully differential amplifier inputs can be biased at
voltages other than midsupply. The common-mode
feedback circuit adjusts for input bias, ensuring the out-
puts are still biased at midsupply. Input capacitors are
not required as long as the input voltage is within the
specified common-mode range listed in the Electrical
Characteristics table.
If input capacitors are used, input capacitor CIN, in con-
junction with the input resistor RIN, forms a highpass filter
that removes the DC bias from an incoming signal. The
AC-coupling capacitor allows the amplifier to bias the sig-
nal to an optimum DC level. Assuming zero-source imped-
ance, the -3dB point of the highpass filter is given by:
3dB IN IN
1
f2 R C
−=
π
Setting f-3dB too high affects the low-frequency response
of the amplifier. Use capacitors with adequately low volt-
age coefficients, such as X7R ceramic capacitors with a
high voltage rating. Capacitors with higher voltage coef-
ficients result in increased distortion at low frequencies.
BIAS Capacitor
BIAS is the output of the internally generated VDD/2 bias
voltage. The BIAS bypass capacitor, CBIAS, improves
PSRR and THD+N by reducing power supply and other
noise sources at the common-mode bias node, and also
generates the clickless/popless startup DC bias wave-
form for the speaker amplifiers. Bypass BIAS with a 0.1FF
capacitor to GND. Larger values of CBIAS (up to 1FF)
improve PSRR.
Supply Bypassing
Proper power-supply bypassing ensures low-noise, low-
distortion performance. Connect a 1FF ceramic capacitor
from VDD to GND. Add additional bulk capacitance as
required by the application. Locate the bypass capacitor
as close as possible to the device.
Layout and Grounding
Good PCB layout is essential for optimizing performance.
Use large traces for the power-supply inputs and amplifier
outputs to minimize losses due to parasitic trace resis-
tance and route heat away from the device. Good ground-
ing improves audio performance, and prevents any digital
switching noise from coupling into the audio signal.
Table 1. Fixed Differential Gain
GAIN CONNECTION GAIN (dB)
VDD 0
GND 3
Unconnected 6
BIAS 9
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MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
Ordering Information
+Denotes a lead(Pb)-free/RoHS-compliant package.
PART TEMP RANGE GAIN PIN-PACKAGE TOP MARK
MAX98309EWL+ -40NC to +85NCExternal 9 WLP +AIY
MAX98310EWL+ -40NC to +85NCFixed 9 WLP +AIZ
���������������������������������������������������������������� Maxim Integrated Products 13
MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
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.
9 WLP (0.3mm pitch) W91D1+1 21-0486 Refer to Application Note 1891
E
D
AAAA
PIN 1
INDICATOR
MARKING
A3
A2
A1
A
See
Note 7
0.05
S
S
D1
E1
b
e
SD
SE
B
A
SIDE VIEW
-DRAWING NOT TO SCALE-
1 2 3
A
21-0486
B
0.64
0.16
0.48
0.025
0.21
0.60
0.60
0.30
W91D1+1
0.95 0.98 0.95 0.98
B
C
TOP VIEW
BOTTOM VIEW
A
1
TITLE
DOCUMENT CONTROL NO.
REV.
1
1
APPROVAL
PACKAGE OUTLINE
9 BUMPS, WLP PKG. 0.3mm PITCH
COMMON DIMENSIONS
A
A2
A1
A3
b
E1
D1
e
SD
SE
0.05
0.03
0.03
BASIC
BASIC
0.00 BASIC
0.00 BASIC
BASIC
REF
BASIC
MIN
MAX MAX
MIN
E
D
PKG. CODE
DEPOPULATED
BUMPS
NONE
NOTES:
1. Terminal pitch is defined by terminal center to center value.
2. Outer dimension is defined by center lines between scribe lines.
3. All dimensions in millimeter.
4. Marking shown is for package orientation reference only.
5. Tolerance is ± 0.02 unless specified otherwise.
6. All dimensions apply to PbFree (+) package codes only.
7. Front - side finish can be either Black or Clear.
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. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 14
© 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX98309/MAX98310
Mono 1.4W Class AB Audio Amplifiers
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 6/11 Initial release —
