MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
General Description
Features
●● 1.4W into 8Ω Load (MAX4364)
The MAX4364/MAX4365 are bridged audio power amplifiers intended for portable audio devices with internal
speakers. The MAX4364 is capable of delivering 1.4W
from a single 5V supply and 500mW from a single 3V supply into an 8Ω load. The MAX4365 is capable of delivering
1W from a single 5V supply and 450mW from a single 3V
supply into an 8Ω load. The MAX4364/MAX4365 feature
0.04% THD+N at 1kHz, 68dB PSRR at 217Hz, and only
10nA of supply current in shutdown mode.
●●
●●
●●
●●
●●
●●
●●
1W into 8Ω Load (MAX4365)
0.04% THD+N at 1kHz
68dB PSRR at 217Hz
2.7V to 5.5V Single-Supply Operation
5mA Supply Current
Low-Power, 10nA Shutdown Mode
Pin Compatible with the LM4861/LM4862/LM4864
(MAX4364)
●● Clickless Power-Up and Shutdown
●● Thermal-Overload and Short-Circuit Protection
●● Available in TDFN, μMAX, and SO Packages
The MAX4364/MAX4365 bridged outputs eliminate the
need for output-coupling capacitors, minimizing external
component count. The MAX4364/MAX4365 also include
internal DC bias generation, clickless operation, shortcircuit and thermal-overload protection. Both devices are
unity-gain stable, with the gain set by two external resistors.
Ordering Information
The MAX4364 is available in a small 8-pin SO package.
The MAX4365 is available in tiny 8-pin TDFN (3mm x
3mm x 0.8mm) and μMAX® packages.
PART
PINPACKAGE
MAX4364ESA/V+T -40°C to +85°C 8 SO
Applications
●●
●●
●●
●●
TEMP RANGE
Cellular Phones
PDAs
Two-Way Radios
General-Purpose Audio
MAX4365EUA+
-40°C to +85°C 8 µMAX
MAX4365ETA+
-40°C to +85°C 8 TDFN-EP*
*EP = Exposed pad.
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
T = Tape and reel.
Pin Configurations appear at end of data sheet.
Typical Application Circuit/Functional Diagram
VCC
6
VCC
50kΩ
CLICKLESS/POPLESS SHDN 1
SHUTDOWN CONTROL
2 BIAS
OUT- 8
CBIAS
50kΩ
10kΩ
3 IN+
AUDIO
INPUT
CIN
10kΩ
OUT+ 5
RIN
4 IN-
MAX4364
RF
μMAX is a registered trademark of Maxim Integrated Products, Inc.
19-2387; Rev 7; 11/17
GND
7
TOP
MARK
—
—
ACD
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Absolute Maximum Ratings
VCC, OUT_ to GND..................................................-0.3V to +6V
IN+, IN-, BIAS, SHDN to GND.................. -0.3V to (VCC + 0.3V)
Output Short Circuit (OUT+ to OUT-) (Note 1)..........Continuous
Continuous Power Dissipation (TA = +70°C)
8-Pin μMAX (derate 4.8mW/°C above +70°C).............388mW
8-Pin TDFN (derate 24.4mW/°C above +70°C).........1951mW
8-Pin SO (derate 7.8mW/°C above +70°C)..................623mW
Junction Temperature.......................................................+150°C
Operating Temperature Range............................ -40°C to +85°C
Storage Temperature Range............................. -65°C to +150°C
Lead Temperature (soldering, 10s).................................. +300°C
Soldering Temperature (reflow) .......................................+260°C
Note 1: Continuous power dissipation must also be observed.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Package Thermal Characteristics (Note 2)
μMAX
Junction-to-Ambient Thermal Resistance (θJA)......206.3°C/W
Junction-to-Case Thermal Resistance (θJC)................42°C/W
TDFN
Junction-to-Ambient Thermal Resistance (θJA)...........41°C/W
Junction-to-Case Thermal Resistance (θJC)..................8°C/W
SO
Junction-to-Ambient Thermal Resistance (θJA)......128.4°C/W
Junction-to-Case Thermal Resistance (θJC)................36°C/W
Note 2: 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.maximintegrated.com/thermal-tutorial.
Electrical Characteristics—5V
(VCC = 5V, RL = ∞, CBIAS = 1μF to GND, VSHDN = VGND, TA = +25°C, unless otherwise noted.) (Note 3)
PARAMETER
Supply Voltage Range
SYMBOL
VCC
CONDITIONS
Inferred from PSRR test
MIN
2.7
MAX4364
Supply Current
ICC
(Note 4)
TYP
7
MAX4364, TA = TMIN to TMAX
ISHDN
VIH
SHDN Threshold
VIL
Common-Mode Bias Voltage
Output Offset Voltage
Power-Supply Rejection Ratio
Output Power
www.maximintegrated.com
VBIAS
VOS
PSRR
POUT
UNITS
5.5
V
13
17
MAX4365
5
MAX4365, TA = TMIN to TMAX
Shutdown Supply Current
MAX
8
11
VSHDN = VCC
0.01
TA = +25°C
VCC x
0.7
TA = -40°C to +85°C
(Note 5)
VCC x
0.7
4
TA = +25°C
VCC x
0.3
TA = -40°C to +85°C
(Note 5)
VCC x
0.3
(Note 6)
mA
µA
V
VCC/2 5%
VCC/2
VCC/2
+ 5%
V
±1
±10
mV
55
75
IN- = OUT+, IN+ = BIAS (Note 7)
VCC = 2.7V to 5.5V
DC
VRIPPLE = 200mVP-P,
RL = 8Ω
217Hz
68
1kHz
58
RL = 8Ω, THD+N = 1%,
fIN = 1kHz (Note 8)
MAX4364
1200
1400
MAX4365
800
1000
dB
mW
Maxim Integrated │ 2
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Electrical Characteristics—5V (continued)
(VCC = 5V, RL = ∞, CBIAS = 1μF to GND, VSHDN = VGND, TA = +25°C, unless otherwise noted.) (Note 3)
PARAMETER
Total Harmonic Distortion Plus
Noise
SYMBOL
THD+N
Noise
Short-Circuit Current
ISC
CONDITIONS
AV = -2V/V, RL = 8Ω,
fIN = 1kHz (Notes 5, 9)
MIN
TYP
MAX4364,
POUT = 1W
0.04
MAX4365,
POUT = 750mW
0.1
MAX
UNITS
%
fIN = 10kHz, BW = 22Hz to 22kHz
12
µVRMS
OUT+ to OUT- (Note 10)
600
mA
Thermal Shutdown Threshold
160
oC
Thermal Shutdown Hysteresis
15
oC
Power-Up Time
tPU
Shutdown Time
tSHDN
Enable Time from Shutdown
tENABLE
TA = +25°C
50
CBIAS = 0.22µF, TA = -40°C to +85°C
(Note 5)
14
35
ms
10
µs
TA = +25°C
50
CBIAS = 0.22µF, TA = -40°C to +85°C
(Note 5)
12
35
TYP
MAX
ms
Electrical Characteristics—3V
(VCC = 3V, RL = ∞, CBIAS = 1μF to GND, VSHDN = VGND, TA = +25°C, unless otherwise noted.) (Note 3)
PARAMETER
Supply Current
SYMBOL
ICC
CONDITIONS
(Note 4)
Shutdown Supply Current
ISHDN
VSHDN = VCC
Output Power
POUT
RL = 8Ω, THD+N =
1%, fIN = 1kHz
(Note 8)
Total Harmonic Distortion Plus
Noise
THD + N
MIN
MAX4364
6
MAX4365
4.5
UNITS
mA
10
MAX4364
400
500
MAX4365
350
450
MAX4364,
AV = -2V/V, RL = 8Ω, POUT = 400mW
fIN = 1kHz (Notes 5, 9) MAX4365,
POUT = 400mW
nA
mW
0.05
%
0.08
Note 3:
Note 4:
Note
Note
Note
Note
Note
Note
All specifications are 100% tested at TA = +25°C.
Quiescent power-supply current is specified and tested with no load on the outputs. Quiescent power-supply current
depends on the offset voltage when a practical load is connected to the amplifier.
5: Guaranteed by design, not production tested.
6: Common-mode bias voltage is the voltage on BIAS and is nominally VCC/2.
7: Maximum differential-output offset voltage is tested in a unity-gain configuration. VOS = VOUT+ - VOUT-.
8: Output power is specified by a combination of a functional output-current test, and characterization analysis.
9: Measurement bandwidth for THD+N is 22Hz to 22kHz.
10: Extended short-circuit conditions result in a pulsed output.
www.maximintegrated.com
Maxim Integrated │ 3
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Typical Operating Characteristics
(VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
THD+N (%)
1
0.25W
0.1
0.25W
1k
10k
100
100
1k
10k
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
VCC = 3V
AV = 4V/V
RL = 8Ω
100
1k
VCC = 3V
AV = 20V/V
RL = 8Ω
THD+N (%)
1
0.25W
0.1
0
10
MAX4364 toc05
10
0.25W
1
0.25W
0.1
0.4W
0.4W
0.01
10k
0
100
1k
0.01
10k
0
100
1k
10k
FREQUENCY (Hz)
FREQUENCY (Hz)
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
20kHz
20Hz
0.1
1kHz
0 40
20kHz
1
20Hz
0.1
1kHz
0.01
200
520
1000
OUTPUT POWER (mW)
www.maximintegrated.com
1650
2450
0.001
0 40
100
MAX4364 toc08
10
VCC = 5V
AV = 4V/V
RL = 8Ω
200
10
THD+N (%)
1
0.01
100
MAX4364 toc07
VCC = 5V
AV = 2V/V
RL = 8Ω
1000
OUTPUT POWER (mW)
1650
2450
VCC = 3V
AV = 2V/V
RL = 8Ω
1
20kHz
0.1
0.01
520
MAX4364 toc09
FREQUENCY (Hz)
THD+N (%)
THD+N (%)
0
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.1
0.001
0.01
10k
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.4W
10
1k
FREQUENCY (Hz)
THD+N (%)
THD+N (%)
0
FREQUENCY (Hz)
1
100
0.5W
1W
FREQUENCY (Hz)
VCC = 3V
AV = 2V/V
RL = 8Ω
0.01
0.25W
1W
0.01
MAX4364 toc04
10
100
1
0.5W
1W
0
VCC = 5V
AV = 20V/V
RL = 8Ω
0.1
0.5W
0.01
10
MAX4364 toc06
0.1
1
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX4364 toc03
VCC = 5V
AV = 4V/V
RL = 8Ω
THD+N (%)
VCC = 5V
AV = 2V/V
RL = 8Ω
THD+N (%)
10
MAX4364 toc01
10
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX4364 toc02
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.001
1kHz
0 20
20Hz
190
525
1000
1700
2500
OUTPUT POWER (mW)
Maxim Integrated │ 4
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Typical Operating Characteristics (continued)
(VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
0.1
1kHz
0.01
200
520
1000
1650
MAX4364 toc12
1800
10% THD+N
1200
4.8
0
5.5
1% THD+N
0
10
20
40
30
50
MAX4364
POWER DISSIPATION vs. OUTPUT POWER
MAX4364
POWER DISSIPATION vs. OUTPUT POWER
10% THD+N
400
700
630
10
490
420
350
280
210
VCC = 5V
fIN = 1kHz
RL = 8Ω
140
70
1% THD+N
0
560
20
40
30
0
50
300
0
600
900
1200
300
270
POWER DISSIPATION (mW)
VCC = 3V
fIN = 1kHz
MAX4364 toc15
MAX4364
OUTPUT POWER vs. LOAD RESISTANCE
MAX4364 toc14
LOAD RESISTANCE (Ω)
200
240
210
180
150
120
90
VCC = 3V
fIN = 1kHz
RL = 8Ω
60
30
0
1500
0
100
200
400
300
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
OUTPUT POWER (mW)
MAX4364
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4364
SUPPLY CURRENT vs. TEMPERATURE
MAX4364
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT (mA)
8.0
7.5
7.0
VCC = 5V
9
8
7
6
6.5
2.7
3.4
4.1
4.8
SUPPLY VOLTAGE (V)
www.maximintegrated.com
5.5
5
12
500
MAX4364 toc18
10
MAX4364 toc16
8.5
SUPPLY CURRENT (mA)
4.1
2400
SUPPLY VOLTAGE (V)
600
6.0
3.4
2.7
VCC = 5V
fIN = 1kHz
600
1% THD+N
10
SUPPLY CURRENT (nA)
OUTPUT POWER (mW)
2440
800
9.0
1000
MAX4364
OUTPUT POWER vs. LOAD RESISTANCE
OUTPUT POWER (mW)
1000
0
10% THD+N
1500
0
3000
MAX4364 toc17
1200
0 40
2000
500
20Hz
POWER DISSIPATION (mW)
0.001
RL = 8Ω
fIN = 1kHz
OUTPUT POWER (mW)
20kHz
MAX4364 toc13
THD+N (%)
1
OUTPUT POWER (mW)
VCC = 3V
AV = 4V/V
RL = 8Ω
10
2500
MAX4364 toc10
100
MAX4364
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4364 toc11
MAX4364
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
8
6
4
2
-40
-15
10
35
TEMPERATURE (°C)
60
85
0
2.7
3.4
4.1
4.8
5.5
SUPPLY VOLTAGE (V)
Maxim Integrated │ 5
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Typical Operating Characteristics (continued)
(VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
60
40
1
0.25W
0.5W
0.1
-15
10
60
35
0
100
1k
0.25W
0.5W
0.1
0.01
10k
0.75W
0
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
VCC = 3V
AV = 2V/V
RL = 8Ω
0.75W
1
VCC = 3V
AV = 4V/V
RL = 8Ω
THD+N (%)
0.25W
10
MAX4364 toc23
10
THD+N (%)
0.5W
0.25W
0.1
1
0.4W
0.1
0.4W
0
100
1k
0
0.25W
100
1k
0.01
10k
0
100
1k
10k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
10
MAX4364 toc27
VCC = 5V
AV = 2V/V
RL = 8Ω
10
100
MAX4364 toc26
100
MAX4364 toc25
VCC = 3V
AV = 20V/V
RL = 8Ω
VCC = 5V
AV = 4V/V
RL = 8Ω
20kHz
0.25W
0.1
1
20Hz
0.1
1kHz
0.01
0.4W
100
1k
FREQUENCY (Hz)
www.maximintegrated.com
10k
0.001
0
200 300 500 700 1000 1300 1600 2000 2400
OUTPUT POWER (mW)
THD+N (%)
20kHz
1
THD+N (%)
THD+N (%)
0.01
10k
10
0
10k
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.1
0.01
1k
FREQUENCY (Hz)
1
0.01
100
FREQUENCY (Hz)
VCC = 5V
AV = 20V/V
RL = 8Ω
MAX4364 toc21
1
TEMPERATURE (°C)
10
THD+N (%)
0.01
85
MAX4364 toc22
-40
VCC = 5V
AV = 4V/V
RL = 8Ω
0.75W
20
0
10
THD+N (%)
80
VCC = 5V
AV = 2V/V
RL = 8Ω
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX4364 toc20
10
MAX4364 toc19
VCC = 5V
THD+N (%)
SUPPLY CURRENT (nA)
100
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX4364 toc24
MAX4364
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
20Hz
1
0.1
1kHz
0.01
0.001
500
750
1000
1300
1600
2000 2400
OUTPUT POWER (mW)
Maxim Integrated │ 6
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Typical Operating Characteristics (continued)
(VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
THD+N (%)
1
20Hz
20kHz
0.1
0.01
20kHz
1
20Hz
0.1
1kHz
0.01
1kHz
2500
MAX4364 toc29
VCC = 3V
AV = 4V/V
RL = 8Ω
10
THD+N (%)
VCC = 3V
AV = 2V/V
RL = 8Ω
10
100
MAX4364 toc28
100
MAX4365
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4364 toc30
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
OUTPUT POWER (mW)
MAX4365
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
RL = 8Ω
fIN = 1kHz
2000
10% THD+N
1500
1000
500
1% THD+N
4.8
5.5
MAX4365
POWER DISSIPATION vs. OUTPUT POWER
400
VCC = 3V
fIN = 1kHz
1000
800
600
10% THD+N
400
200
0
10
20
30
40
0
50
800
MAX4364 toc33
1200
POWER DISSIPATION (mW)
VCC = 5V
fIN = 1kHz
MAX4364 toc32
MAX4365
OUTPUT POWER vs. LOAD RESISTANCE
OUTPUT POWER (mW)
600
400
200
VCC = 5V
RL = 8Ω
fIN = 1kHz
1% THD+N
0
10
20
40
30
0
50
0
300
600
900
1200
1500
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
MAX4365
POWER DISSIPATION vs. OUTPUT POWER
MAX4365
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4365
SUPPLY CURRENT vs. TEMPERATURE
200
150
100
VCC = 3V
RL = 8Ω
fIN = 1kHz
50
0
100
200
300
OUTPUT POWER (mW)
www.maximintegrated.com
400
500
SUPPLY CURRENT (mA)
MAX4364 toc34
7
6
5
4
3
7
2.7
3.4
4.1
4.8
SUPPLY VOLTAGE (V)
5.5
MAX4364 toc36
LOAD RESISTANCE (Ω)
SUPPLY CURRENT (mA)
OUTPUT POWER (mW)
4.1
MAX4365
OUTPUT POWER vs. LOAD RESISTANCE
200
POWER DISSIPATION (mW)
3.4
SUPPLY VOLTAGE (V)
600
0
2.7
OUTPUT POWER (mW)
800
250
0 125 200 250 325 400 500 600 725 850 1000
OUTPUT POWER (mW)
1000
0
0
MAX4364 toc35
1200
0 125 200 250 325 400 500 600 725 800 1000
0.001
MAX4364 toc31
0.001
VCC = 5V
6
5
4
3
-40
-15
10
35
60
85
TEMPERATURE (°C)
Maxim Integrated │ 7
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Typical Operating Characteristics (continued)
(VCC = 5V, THD+N measurement bandwidth = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.)
8
6
4
2
3.4
4.1
4.8
SUPPLY VOLTAGE (V)
50
40
30
20
0
5.5
-40
-15
10
60
35
85
TEMPERATURE (°C)
GAIN AND PHASE vs. FREQUENCY
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-20
MAX4364 toc40
2.7
RL = 8Ω
VRIPPLE = 200mVP-P
-30
-40
PSRR (dB)
80
60
40
20
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
60
10
MAX4364 toc39
GAIN/PHASE (dB/DEGREES)
0
VCC = 5V
70
SUPPLY CURRENT (nA)
10
SUPPLY CURRENT (nA)
80
MAX4364 toc37
12
MAX4365
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX4364 toc38
MAX4365
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
-50
-60
-70
AV = 1000V/V
10
100
1k
10k
100k
1M
10M
-80
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
Pin Description
PIN
MAX4364
MAX4365
SO
µMAX/TDFN
1
7
SHDN
Active-High Shutdown. Connect SHDN to GND for normal operation.
2
1
BIAS
DC Bias Bypass. See BIAS Capacitor section for capacitor selection. Connect CBIAS
capacitor from BIAS to GND.
3
2
IN+
Noninverting Input
4
4
IN-
Inverting Input
5
5
OUT+
6
6
VCC
Power Supply
7
3
GND
Ground
8
8
OUT-
Bridged Amplifier Negative Output
—
—
EP
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NAME
FUNCTION
Bridged Amplifier Positive Output
Exposed Pad (TDFN Only). Internally connected to GND. Connect to a large ground
plane to maximize thermal performance. Not intended as an electrical connection point.
Maxim Integrated │ 8
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Detailed Description
The MAX4364/MAX4365 bridged audio power amplifiers can deliver 1.4W into 8Ω (MAX4364) or 1W into
8Ω (MAX4365) while operating from a single 5V supply.
These devices consist of two high-output-current op amps
configured as a bridge-tied load (BTL) amplifier (see
Typical Application Circuit/Functional Diagram). The gain
of the device is set by the closed-loop gain of the input op
amp. The output of the first amplifier serves as the input
to the second amplifier, which is configured as an inverting unity-gain follower in both devices. This results in two
outputs, identical in magnitude, but 180° out of phase.
BIAS
The MAX4364/MAX4365 feature an internally generated
common-mode bias voltage of VCC/2 referenced to GND.
BIAS provides both click-and-pop suppression and the DC
bias level for the audio signal. BIAS is internally connected
to the noninverting input of one amplifier, and should be
connected to the noninverting input of the other amplifier
for proper signal biasing (see Typical Application Circuit/
Functional Diagram). Choose the value of the bypass
capacitor as described in the BIAS Capacitor section.
Shutdown
The MAX4364/MAX4365 feature a 10nA, low-power shutdown mode that reduces quiescent current consumption.
Pulling SHDN high disables the device’s bias circuitry, the
amplifier outputs go high impedance, and BIAS is driven
to GND. Connect SHDN to GND for normal operation.
Current Limit
The MAX4364/MAX4365 feature a current limit that protects the device during output short circuit and overload
conditions. When both amplifier outputs are shorted to
either VCC or GND, the short-circuit protection is enabled
and the amplifier enters a pulsing mode, reducing the
average output current to a safe level. The amplifier
remains in this mode until the overload or short-circuit
condition is removed.
Applications Information
Bridge-Tied Load
The MAX4364/MAX4365 are designed to drive a load
differentially in a BTL configuration. 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. Thus, the differential gain of the device is
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VOUT(P-P)
+1
2 x VOUT(P-P)
VOUT(P-P)
-1
Figure 1. Bridge-Tied Load Configuration
twice the closed-loop gain of the input amplifier. The effective gain is given by:
A V D= 2 ×
RF
R IN
Substituting 2 VOUT(P-P) into the following equations
yields four times the output power due to doubling of the
output voltage.
VRMS =
V O U T (P −P )
PO UT =
2 2
VRMS 2
RL
Since the differential outputs are biased at midsupply,
there is no net DC voltage across the load. This eliminates the need for DC-blocking capacitors required for
single-ended amplifiers. These capacitors can be large,
expensive, consume board space, and degrade lowfrequency performance.
Power Dissipation
Under normal operating conditions, the MAX4364/
MAX4365 can dissipate a significant amount of power.
The maximum power dissipation for each package is
given in the Absolute Maximum Ratings section under
Continuous Power Dissipation or can be calculated by the
following equation:
P D IS S P K G (M A X ) =
T J(M A X ) − T A
θ JA
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 Package Thermal Characteristics section.
For example, θJA of the μMAX package is 206.3°C/W.
Maxim Integrated │ 9
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
The increase in power delivered by the BTL configuration
directly results in an increase in internal power dissipation
over the single-ended configuration. The maximum power
dissipation for a given VCC and load is given by the following equation:
P D IS S P (M A X ) =
The MAX4365 TDFN package features an exposed thermal pad on its underside. This pad lowers the thermal
resistance of the package by providing a direct heat conduction path from the die to the PC board. Connect the
exposed thermal pad to circuit ground by using a large
pad, ground plane, or multiple vias to the ground plane.
Efficiency
The efficiency of the MAX4364/MAX4365 is calculated by
taking the ratio of the power delivered to the load to the
power consumed from the power supply. Output power is
calculated by the following equations:
VPEAK
2R L
2
where VPEAK is half the peak-to-peak output voltage. In
BTL amplifiers, the supply current waveform is a fullwave
rectified sinusoid with the magnitude proportional to the
peak output voltage and load. Calculate the supply current and power drawn from the power supply by the following:
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PO UT
=
η
=
P IN
π 2R L
Thermal-overload protection limits total power dissipation in the MAX4364/MAX4365. When the junction temperature exceeds +160°C, the thermal protection circuitry
disables the amplifier output stage. The amplifiers are
enabled once the junction temperature cools by 15°C.
This results in a pulsing output under continuous thermal
overload conditions as the device heats and cools.
ICC =
The efficiency of the MAX4364/MAX4365 is:
2VCC 2
If the power dissipation for a given application exceeds
the maximum allowed for a given package, reduce VCC,
increase load impedance, decrease the ambient temperature or add heat sinking to the device. Large output, supply, and ground PC board traces improve the maximum
power dissipation in the package.
PO UT =
2V
P IN = V C C P E A K
πR L
2VPEAK
πR L
π
PO U TR L
2
2VCC
The device efficiency values in Table 1 are calculated
based on the previous equation and do include the effects
of quiescent current. Note that efficiency is low at low
output-power levels, but remains relatively constant at
normal operating, output-power levels.
Component Selection
Gain-Setting Resistors
External feedback components set the gain of both
devices. Resistors RF and RIN (see Typical Application
Circuit/Functional Diagram) set the gain of the amplifier
as follows:
A V D= 2 ×
RF
R IN
Optimum output offset is achieved when RF = 20kΩ.
Vary the gain by changing the value of RIN. When using
the MAX4364/MAX4365 in a high-gain configuration
(greater than 8V/V), a feedback capacitor may be required
to maintain stability (see Figure 2). CF and RF limit the
bandwidth of the device, preventing high-frequency oscillations. Ensure that the pole created by CF and RF is not
within the frequency band of interest.
Input Filter
The input capacitor (CIN), in conjunction with RIN forms a
highpass filter that removes the DC bias from an incoming signal. The AC-coupling capacitor allows the amplifier
to bias the signal to an optimum DC level. Assuming zero
source impedance, the -3dB point of the highpass filter is
given by:
f −3D B =
1
2 πR IN C IN
Choose RIN according to the Gain-Setting Resistors
section. Choose CIN such that f-3dB is well below the
lowest frequency of interest. Setting f-3dB too high
affects the low-frequency response of the amplifier. Use
capacitors whose dielectrics have low-voltage coeffi-
Maxim Integrated │ 10
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
VCC
6
VCC
50kΩ
2
50kΩ
3
AUDIO INPUT
SHDN
1
OUT-
8
BIAS
CBIAS
CIN
CLICKLESS/
POPLESS
SHUTDOWN
CONTROL
IN+
10kΩ
10kΩ
OUT+ 5
RIN
4
IN-
MAX4364
MAX4365
GND
7
RF
CF
Figure 2. High-Gain Configuration
Table 1. Efficiency in a 5V, 8Ω BTL System
OUTPUT
POWER (W)
INTERNAL POWER
DISSIPATION (W)
EFFICIENCY (%)
0.25
0.55
31.4
0.50
0.63
44.4
human voice (typically 300Hz to 3.5kHz). In addition,
speakers used in portable devices typically have a poor
response below 150Hz. Taking these two factors into consideration, the input filter may not need to be designed for
a 20Hz to 20kHz response, saving both board space and
cost due to the use of smaller capacitors.
0.75
0.63
54.4
BIAS Capacitor
1.00
0.59
62.8
1.25
0.53
70.2
1.40
0.48
74.3
The BIAS bypass capacitor, CBIAS, improves PSRR and
THD+N by reducing power-supply noise at the commonmode bias node, and serves as the primary clickandpop suppression mechanism. CBIAS is fed from an
internal 25kΩ source, and controls the rate at which the
common-mode bias voltage rises at startup and falls during shutdown. For optimum click-and-pop suppression,
ensure that the input capacitor (CIN) is fully charged (ten
time constants) before CBIAS. The value of CBIAS for best
click-and-pop suppression is given by:
cients, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as
ceramics, may result in an increase distortion at low
frequencies.
Other considerations when designing the input filter
include the constraints of the overall system, the actual
frequency band of interest and click-and-pop suppression.
Although high-fidelity audio calls for a flat gain response
between 20Hz and 20kHz, portable voicereproduction
devices such as cellular phones and twoway radios need
only concentrate on the frequency range of the spoken
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C R
C B IA S ≥ 1 0 IN IN
2 5k Ω
In addition, a larger CBIAS value yields higher PSRR.
Maxim Integrated │ 11
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Clickless/Popless Operation
RF
Proper selection of AC-coupling capacitors (CIN) and
CBIAS achieves clickless/popless shutdown and startup.
The value of CBIAS determines the rate at which the midrail bias voltage rises on startup and falls when entering
shutdown. The size of the input capacitor also affects
clickless/popless operation. On startup, CIN is charged
to its quiescent DC voltage through the feedback resistor (RF) from the output. This current creates a voltage
transient at the amplifier’s output, which can result in
an audible pop. Minimizing the size of CIN reduces this
effect, optimizing click-and-pop suppression.
AUDIO
INPUT
1 H
MAX5407
OUT+
RIN
W 3
MAX4364
INMAX4365
CIN
4 L
OUT-
Figure 3. MAX4364/MAX4365 and MAX5160 Volume Control
Circuit
Supply Bypassing
passes the audio signal unattenuated. Setting the wiper to
the lowest position fully attenuates the input.
Proper supply bypassing ensures low-noise, low-distortion
performance. Place a 0.1μF ceramic capacitor in parallel
with a 10μF ceramic capacitor from VCC to GND. Locate
the bypass capacitors as close to the device as possible.
Layout Considerations
Good layout improves performance by decreasing the
amount of stray capacitance and noise at the amplifier’s inputs and outputs. Decrease stray capacitance by
minimizing PC board trace lengths, using surface-mount
components and placing external components as close to
the device as possible. Also refer to the Power Dissipation
section for heatsinking considerations.
Adding Volume Control
The addition of a digital potentiometer provides simple
volume control. Figure 3 shows the MAX4364/MAX4365
with the MAX5407 log taper digital potentiometer used
as an input attenuator. Connect the high terminal of the
MAX5407 to the audio input, the low terminal to ground
and the wiper to CIN. Setting the wiper to the top position
Chip Information
PROCESS: BiCMOS
Pin Configurations
TOP VIEW
OUT- SHDN VCC OUT+
SHDN
1
BIAS
2
IN+
IN-
+
8
OUT-
7
GND
3
6
VCC
4
5
OUT+
MAX4364
SO
BIAS
1
IN+
2
GND
3
IN-
4
+
MAX4365
MAX
8
OUT-
7
SHDN
6
VCC
5
OUT+
8
7
6
5
MAX4364
MAX4365
EP*
+
1
2
3
4
BIAS
IN+
GND
IN-
TDFN
*CONNECT EP TO GND.
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Maxim Integrated │ 12
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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.
8 SO
S8+19F
21-0041
90-0096
8 μMAX
U8+1
21-0036
90-0092
8 TDFN
T833+2
21-0137
90-0059
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Maxim Integrated │ 13
MAX4364/MAX4365
1.4W and 1W, Ultra-Small, Audio Power
Amplifiers with Shutdown
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
4
5/11
Added EP information to Pin Description; updated Ordering Information and Pin
Configurations for lead-free parts; updated specifications in Absolute Maximum
Ratings, Package Thermal Characteristics and Electrical Characteristics sections
5
6/17
Changed orderable part number from MAX4364ESA+ to MAX4364ESA/V+T in
Ordering Information table
1
6
10/17
Updated SO package code
13
7
11/17
Changed SO package code from S8-19F to S8+19F
13
DESCRIPTION
1, 2, 3, 8, 9,
12, 13
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated 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 and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2017 Maxim Integrated Products, Inc. │ 14
