MAXIM MAX4368ETA

19-2338; Rev 1; 10/02
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
The MAX4366/MAX4367/MAX4368 bridged outputs eliminate the need for output-coupling capacitors minimizing
external component count. The MAX4366/
MAX4367/MAX4368 also feature a low-power shutdown
mode, clickless power-up/power-down and internal DC
bias generation. The MAX4366 is a unity-gain stable, programmable gain amplifier. The MAX4367/MAX4368 feature internally preset gains of 2V/V and 3V/V, respectively.
Features
♦ Drives 330mW into 32Ω (200mW into 16Ω)
♦ 0.02% THD + N at 1kHz (120mW into 32Ω)
♦ Internal Bridged Configuration
♦
♦
♦
♦
No Output-Coupling Capacitors
2.3V to 5.5V Single-Supply Operation
2mA Supply Current
Low-Power Shutdown Mode
♦ Clickless Power-Up and Shutdown
♦ Thermal Overload Protection
♦ Available in SOT23, Thin QFN, µMAX, and UCSP
Packages
All devices are available in space-saving 8-pin SOT23,
thin QFN and µMAX packages, and an 8-bump chipscale package (UCSP™).
Applications
Cellular Phones
Two-Way Radios
PDAs
Headphones
Headsets
General-Purpose Audio
Ordering Information
PART
TEMP RANGE
PIN/BUMPPACKAGE
TOP
MARK
MAX4366EBL-T* -40°C to +85°C
8 UCSP-8
AAK
MAX4366EKA-T -40°C to +85°C
8 SOT23-8
AAIO
MAX4366EUA
-40°C to +85°C
8 µMAX
MAX4366ETA
-40°C to +85°C
8 Thin QFN-EP**
—
AAC
*Future product—contact factory for availability.
**EP = Exposed paddle.
Ordering Information continued at end of data sheet.
Selector Guide and Functional Diagrams appear at end of
data sheet.
Pin Configurations
Typical Operating Circuit
TOP VIEW
(BUMP SIDE
DOWN)
VCC
1
2
IN-
OUT+
3
VCC
A
IN+
CLICKLESS/POPLESS
SHUTDOWNCONTROL
SHDN
BIAS
OUTB
C
GND
MAX4366
MAX4367
MAX4368
VCC
IN+
AUDIO
INPUT
BIAS
OUT-
SHDN
UCSP
OUT+
IN-
MAX4367
MAX4368
GND
Pin Configurations continued at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX4366/MAX4367/MAX4368
General Description
The MAX4366/MAX4367/MAX4368 are bridged audio
power amplifiers intended for devices with internal
speakers and headsets. The MAX4366/MAX4367/
MAX4368 are capable of delivering 330mW of continuous power into a 32Ω load, or 200mW into a 16Ω load
with 1% THD + N from a single 5V supply.
MAX4366/MAX4367/MAX4368
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
ABSOLUTE MAXIMUM RATINGS
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Bump Temperature (soldering) (Note 2)
Infrared (15s) ................................................................+220°C
Vapor Phase (60s) ........................................................+215°C
VCC to GND ..............................................................-0.3V to +6V
IN+, IN-, BIAS, SHDN.................................-0.3V to (VCC + 0.3V)
Output Short Circuit to VCC or GND (Note 1).............Continuous
Output Short Circuit (OUT+ to OUT-) (Note 1)...........Continuous
Continuous Power Dissipation (TA = +70°C)
8-Bump UCSP (derate 4.7mW/°C above +70°C)..........379mW
8-Pin SOT23 (derate 9.7mW/°C above +70°C).............777mW
8-Pin µMAX (derate 4.5mW/°C above +70°C) ..............362mW
8-Pin Thin QFN (derate 24.4mW°C above +70°C) .....1951mW
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
(VCC = 5V, RL = ∞, RIN = RF = 30kΩ, CBIAS = 1µF to GND, SHDN = GND, IN+ = BIAS, TA = TMIN to TMAX, unless otherwise noted.
Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
Supply Voltage Range
VCC
Inferred from PSRR test
Supply Current
ICC
(Note 4)
Shutdown Supply Current
SHDN Threshold
ISHDN
SHDN = VCC
MIN
2.3
35
VIH
VCC/2
- 5%
(Note 5)
VOS
MAX4367, IN- = open
±5
MAX4366 (open loop)
AV
Input Common-Mode Range
VCM
Differential Input Resistance
RIN(DIFF)
Input Resistance
(Note 6)
µA
±5
±15
±5
±15
±7.5
±15
V
mV
dB
V/V
VCC 1.0
0.3
V
MAX4366, VIN+ - VIN- = 10mV
500
kΩ
VIN- = 0V to VCC (MAX4367/MAX4368)
20
kΩ
TA = +25°C
70
TA = TMIN to TMAX
66
Common-Mode Rejection Ratio
CMRR
0V ≤ VCM ≤ VCC - 1.0V (MAX4366)
PO
VCC/2
+ 5%
3
VCC = 2.3V to
5.5V
IOUT
VCC/2
2
V
nA
100
(Note 7)
2.7V ≤ VCC ≤ 5.5V,
0.6V ≤ VOUT ≤ VCC - 0.6V
f = 1kHz,
THD + N <1%
(Note 8)
80
80
±87
dB
dB
±125
mA
2.3V ≤ VCC ≤ 2.7V,
0.6V ≤ VOUT ≤ VCC - 0.6V
2
100
MAX4368 (internally set)
PSRR
Output Power
40
MAX4367 (internally set)
Power-Supply Rejection Ratio
Output Source/Sink Current
mA
0.8
MAX4368, IN- = open
Differential Voltage Gain
V
4.3
-400
VBIAS
UNITS
5.5
1.8
MAX4366, RIN = ∞
Output Offset Voltage
MAX
2
VIL
SHDN Input Bias Current
Common-Mode Bias Voltage
TYP
±115
RL = 16Ω
60
200
RL = 32Ω
120
330
mW
_______________________________________________________________________________________
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
(VCC = 5V, RL = ∞, RIN = RF = 30kΩ, CBIAS = 1µF to GND, SHDN = GND, IN+ = BIAS, TA = TMIN to TMAX, unless otherwise noted.
Typical values are at TA = +25°C.) (Note 3)
PARAMETER
Total Harmonic Distortion Plus
Noise
SYMBOL
THD + N
Noise
CONDITIONS
AV = -2V/V, f = 1kHz
(MAX4366)
(Notes 9 and 10)
ISC
Thermal Shutdown Threshold
TYP
PO = 60mW, RL = 16Ω
0.04
PO = 120mW, RL = 32Ω
0.02
20
To VCC
185
To GND
215
165
Thermal Shutdown Hysteresis
MAX
UNITS
%
f = 10kHz, referred to input
Short-Circuit Current
MIN
0.15
nV/√Hz
mA
°C
10
°C
Power-Up Time
tPU
60
ms
Shutdown Time
tSHDN
20
ms
tENABLE
60
ms
Enable Time from Shutdown
Note 1: Continuous power dissipation must also be observed.
Note 2: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device
can be exposed to during board-level solder attach and rework. This limit permits only the use of the solder profiles recommended in the industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and convection reflow.
Preheating is required. Hand or wave soldering is not allowed.
Note 3: All specifications are 100% tested at TA = +25°C; temperature limits are guaranteed by design.
Note 4: 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.
Note 5: Common-mode bias voltage is the voltage on BIAS and is nominally VCC/2.
Note 6: Differential voltage gain for the MAX4366 is specified as an open-loop parameter because external resistors are used to set
the closed-loop gain. The MAX4367/MAX4368 contain internal feedback resistors that preset the differential voltage gain.
Differential voltage gain is defined as (VOUT+ - VOUT-) / (VIN - VBIAS). All gains are specified over an output voltage range of
0.6V ≤ VOUT ≤ 4.4V.
Note 7: Specification applies to either output. An amplifier peak output current of 87mA is required to support an output load power
of 60mW for a 16Ω load, or 120mW for a 32Ω load.
Note 8: Output power specifications are inferred from the output current test. For 60mW into a 16Ω load, IOUT(PEAK) is 87mA and
VOUT(P-P) is 1.39V per amplifier. For 120mW into a 32Ω load, IOUT(PEAK) is 87mA and VOUT(P-P) is 2.77V per amplifier.
Note 9: Guaranteed by design. Not production tested.
Note 10: Measurement bandwidth for THD + N is 20Hz to 20kHz.
Note 11: Power-up and shutdown times are for the output to reach 90% of full scale with CBIAS = 1µF.
_______________________________________________________________________________________
3
MAX4366/MAX4367/MAX4368
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(Bridge-Tied Load, THD + N Bandwidth = 22Hz to 22kHz, CBIAS = 1µF.)
VCC = 5V
AV = 3V/V
RL = 16Ω
0.1
THD + N (%)
0.1
POUT = 25mW
POUT = 25mW
0.01
POUT = 10mW
POUT = 10mW
THD + N (%)
POUT = 25mW
POUT = 60mW
POUT = 60mW
VCC = 5V
AV = 4V/V
RL = 16Ω
0.001
0.001
0.001
10
0.1
0.01
0.01
POUT = 60mW
100
1k
10k
10
100k
100
1k
10k
10
100k
100
1k
10k
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX4366 toc04
1
VCC = 5V
AV = 2V/V
RL = 32Ω
1
VCC = 5V
AV = 3V/V
RL = 32Ω
POUT = 60mW
0.1
THD + N (%)
POUT = 25mW
POUT = 50mW
0.01
0.01
VCC = 5V
AV = 20V/V
RL = 16Ω
POUT = 75mW
POUT = 120mW
0.001
100
1k
10k
POUT = 50mW
POUT = 120mW
0.001
10
0.1
0.01
POUT = 75mW
0.001
10
100k
100
1k
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
1
POUT = 50mW
THD + N (%)
POUT = 50mW
0.1
POUT = 75mW
0.1
POUT = 120mW
POUT = 75mW
VCC = 3V
AV = 2V/V
RL = 16Ω
0.1
POUT = 10mW
POUT = 25mW
0.01
0.01
0.01
1
THD + N (%)
VCC = 5V
AV = 4V/V
RL = 32Ω
MAX4366 toc07
1
POUT = 120mW
POUT = 60mW
VCC = 5V
AV = 20V/V
RL = 32Ω
0.001
0.001
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
MAX4366 toc09
FREQUENCY (Hz)
MAX4366 toc08
THD + N (%)
THD + N (%)
POUT = 10mW
0.1
MAX4366 toc06
FREQUENCY (Hz)
1
4
100k
FREQUENCY (Hz)
MAX4366 toc05
THD + N (%)
POUT = 10mW
1
MAX4366 toc03
1
MAX4366 toc02
VCC = 5V
AV = 2V/V
RL = 16Ω
MAX4366 toc01
1
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
THD + N (%)
MAX4366/MAX4367/MAX4368
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
FREQUENCY (Hz)
_______________________________________________________________________________________
10k
100k
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
MAX4366 toc11
1
POUT = 60mW
POUT = 25mW
0.1
POUT = 60mW
POUT = 25mW
0.01
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
THD + N (%)
POUT = 10mW
POUT = 10mW
THD + N (%)
0.01
POUT = 60mW
0.1
POUT = 10mW
POUT = 25mW
0.01
VCC = 3V
AV = 4V/V
RL = 16Ω
0.001
0.001
10
100
1k
10k
10
100
1k
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
POUT = 25mW
1
POUT = 25mW
0.01
0.01
POUT = 25mW
0.01
0.001
0.001
100
0.1
POUT = 50mW
POUT = 50mW
POUT = 50mW
10
VCC = 3V
AV = 4V/V
RL = 32Ω
POUT = 10mW
POUT = 10mW
0.1
THD + N (%)
0.1
VCC = 3V
AV = 3V/V
RL = 32Ω
THD + N (%)
VCC = 3V
AV = 2V/V
RL = 32Ω
MAX4366 toc14
1
MAX4366 toc13
POUT = 10mW
1k
10k
0.001
10
100k
100
1k
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
POUT = 25mW
THD + N (%)
0.1
10
POUT = 50mW
f = 10kHz
1
f = 1kHz
0.1
100
10
THD + N (%)
POUT = 10mW
MAX4366 toc18
100
MAX4366 toc16
1
MAX4366 toc17
THD + N (%)
0.001
100k
1
THD + N (%)
VCC = 3V
AV = 20V/V
RL = 16Ω
MAX4366 toc15
THD + N (%)
VCC = 3V
AV = 3V/V
RL = 16Ω
0.1
1
MAX4366 toc10
1
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX4366 toc12
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
1
f = 10kHz
0.1
0.01
VCC = 3V
AV = 20V/V
RL = 32Ω
VCC = 5V
AV = 2V/V
RL = 16Ω
0.01
0.001
0.01
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
VCC = 5V
AV = 4V/V
RL = 16Ω
f = 1kHz
0.001
0
100
200
300
OUTPUT POWER (mW)
400
0
100
200
300
400
OUTPUT POWER (mW)
_______________________________________________________________________________________
5
MAX4366/MAX4367/MAX4368
Typical Operating Characteristics (continued)
(Bridge-Tied Load, THD + N Bandwidth = 22Hz to 22kHz, CBIAS = 1µF.)
Typical Operating Characteristics (continued)
(Bridge-Tied Load, THD + N Bandwidth = 22Hz to 22kHz, CBIAS = 1µF.)
f = 10kHz
f = 1kHz
f = 10kHz
0.1
0.01
0.001
0.001
100
200
300
400
f = 10kHz
0.1
0.01
f = 1kHz
0.001
100
0
200
300
400
75
0
150
225
300
OUTPUT POWER (mW)
OUTPUT POWER (mW)
OUTPUT POWER (mW)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
f = 10kHz
0.1
f = 10kHz
0.1
0.01
300
225
75
150
300
225
0
75
OUTPUT POWER (mW)
RL = 16Ω
500
OUTPUT POWER (mW)
THD + N = 10%
300
THD + N = 1%
200
225
OUTPUT POWER vs. SUPPLY VOLTAGE
600
MAX4366 toc25
RL = 32Ω
150
OUTPUT POWER (mW)
OUTPUT POWER vs. SUPPLY VOLTAGE
500
OUTPUT POWER (mW)
MAX4366 toc24
0.001
0
OUTPUT POWER (mW)
400
VCC = 3V
AV = 4V/V
RL = 32Ω
f = 1kHz
MAX4366 toc26
150
0.1
0.01
0.001
75
1
f = 1kHz
0.001
0
f = 10kHz
10
1
VCC = 3V
AV = 4V/V
RL = 16Ω
f = 1kHz
VCC = 3V
AV = 2V/V
RL = 32Ω
THD + N (%)
1
0.01
10
THD + N (%)
10
100
MAX4366 toc23
100
MAX4366 toc22
100
400
THD + N = 10%
300
200
THD + N = 1%
100
100
0
0
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
6
1
VCC = 5V
AV = 4V/V
RL = 32Ω
f = 1kHz
VCC = 3V
AV = 2V/V
RL = 16Ω
10
1
0.01
0
100
THD + N (%)
1
0.1
10
THD + N (%)
THD + N (%)
10
100
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4366 toc20
VCC = 5V
AV = 2V/V
RL = 32Ω
MAX4366 toc19
100
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4366 toc21
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
THD + N (%)
MAX4366/MAX4367/MAX4368
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5.5
300
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
OUTPUT POWER vs. LOAD
250
THD + N = 1%
AV = 2V/V
200
150
VCC = 5V
f = 1kHz
100
50
150
THD + N = 1%
AV = 2V/V
100
VCC = 3V
f = 1kHz
50
0
0
1k
10k
10
100
LOAD RESISTANCE (Ω)
POWER DISSIPATION vs. OUTPUT POWER
400
POWER DISSIPATION (mW)
POWER DISSIPATION (mW)
VCC = 5V
AV = 2V/V
RL = 16Ω
300
200
RL = 32Ω
0
VCC = 3V
AV = 2V/V
150
RL = 16Ω
100
50
RL = 32Ω
0
0
50
100
150
200
0
20
OUTPUT POWER (mW)
MAX4366 toc31
VCC = 5V
AV = 2V/V
SINGLE ENDED
GAIN (dB)/PHASE (deg)
150
RL = 16Ω
100
50
RL = 32Ω
0
10
20
30
OUTPUT POWER (mW)
60
80
100
GAIN AND PHASE vs. FREQUENCY
POWER DISSIPATION vs. OUTPUT POWER
0
40
OUTPUT POWER (mW)
200
POWER DISSIPATION (mW)
10k
POWER DISSIPATION vs. OUTPUT POWER
200
MAX4366 toc29
500
100
1k
LOAD RESISTANCE (Ω)
MAX4366 toc30
100
10
40
50
80
60
40
20
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
MAX4366 toc32
OUTPUT POWER (mW)
300
THD + N = 10%
AV = 20V/V
200
OUTPUT POWER (mW)
THD + N = 10%
AV = 20V/V
350
MAX4366 toc28
400
OUTPUT POWER vs. LOAD
250
MAX4366 toc27
450
GAIN
PHASE
VCC = 5V
AV = 1000V/V
SINGLE ENDED
NO LOAD
100
1k
10k
100k
1M
10M
100M
FREQUENCY (Hz)
_______________________________________________________________________________________
7
MAX4366/MAX4367/MAX4368
Typical Operating Characteristics (continued)
(Bridge-Tied Load, THD + N Bandwidth = 22Hz to 22kHz, CBIAS = 1µF.)
Typical Operating Characteristics (continued)
(Bridge-Tied Load, THD + N Bandwidth = 22Hz to 22kHz, CBIAS = 1µF.)
DIFFERENTIAL POWER-SUPPLY
REJECTION RATIO vs. FREQUENCY
SUPPLY CURRENT vs. SUPPLY VOLTAGE
-10
2.0
SUPPLY CURRENT (mA)
-30
VCC = 3V
-50
-60
1.5
1.0
0.5
VCC = 5V
-70
0
-80
10
100
1k
10k
100k
0
1M
1
2
3
4
FREQUENCY (Hz)
SUPPLY VOLTAGE (V)
SUPPLY CURRENT vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
45
2.5
2.0
SHUTDOWN SUPPLY CURRENT (µA)
MAX4366 toc35
3.0
VCC = 5V
1.5
5
VCC = 3V
1.0
0.5
MAX4366 toc36
PSRR (dB)
-20
-40
MAX4366 toc34
2.5
MAX4366 toc33
0
SUPPLY CURRENT (mA)
40
35
30
25
20
15
10
5
0
0
-40
-15
10
35
85
60
0
1
TEMPERATURE (°C)
2
3
4
5
SUPPLY VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX4366 toc37
50
45
40
SUPPLY CURRENT (µA)
MAX4366/MAX4367/MAX4368
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
VCC = 5V
35
30
25
VCC = 3V
20
15
10
5
0
-40
-15
10
35
60
85
TEMPERATURE (°C)
8
_______________________________________________________________________________________
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
PIN/BUMP
NAME
SOT23/µMAX/
QFN
UCSP
1
C3
FUNCTION
SHDN
Active-High Shutdown. Connect SHDN to GND for normal operation.
C1
BIAS
DC Bias Bypass. See BIAS Capacitor section for capacitor selection. Connect
CBIAS capacitor from BIAS to GND.
3
A3
IN+
Noninverting Input
4
A1
IN-
Inverting Input
5
A2
OUT+
6
B3
VCC
Power Supply
2
Bridged Amplifier Positive Output
7
B1
GND
Ground
8
C2
OUT-
Bridged Amplifier Negative Output
Detailed Description
The MAX4366/MAX4367/MAX4368 bridged audio
power amplifiers can deliver 330mW into a 32Ω load, or
200mW into a 16Ω load, while operating from a single
5V supply. These devices consist of two high-outputcurrent op amps configured as a bridge-tied load (BTL)
amplifier (see Functional Diagram). The closed-loop
gain of the input op amp sets the single-ended gain of
the device. Two external resistors set the gain of the
MAX4366 (see Gain-Setting Resistors section). The
MAX4367/MAX4368 feature internally fixed gains of
2V/V and 3V/V, respectively. The output of the first
amplifier serves as the input to the second amplifier,
which is configured as an inverting unity-gain follower
in all three devices. This results in two outputs, identical
in magnitude, but 180° out of phase.
BIAS
The MAX4366/MAX4367/MAX4368 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 (Typical Application Circuit). Choose the value
of the bypass capacitor as described in the BIAS
Capacitor section.
Shutdown
The MAX4366/MAX4367/MAX4368 feature a 35µA, lowpower shutdown mode that reduces quiescent current
consumption and extends battery life. Pulling SHDN
OUT+
+1
RL
2 x OUT
OUT-
-1
Figure 1. Bridge-Tied Load Configuration
high disables the device’s bias circuitry and drives
OUT+, OUT-, and BIAS to GND. Connect SHDN to
GND for normal operation.
Applications Information
Bridge-Tied Load
The MAX4366/MAX4367/MAX4368 are designed to
drive a load differentially, a configuration referred to as
bridge-tied load (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. The differential gain of the device is twice
the closed-loop gain of the input amplifier. The effective
gain of the MAX4366 is given by:
A VD = 2 ×
RF
RIN
_______________________________________________________________________________________
9
MAX4366/MAX4367/MAX4368
Pin Description
MAX4366/MAX4367/MAX4368
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
The effective gains of the MAX4367 and MAX4368 are
AVD = 2V/V and AVD = 3V/V respectively. 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.
VRMS =
VOUT(P−P)
2 2
2
V
POUT = RMS
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
low-frequency performance.
In single-ended mode, the load must be capacitively
coupled to the device output to block the half-supply
DC voltage from the load (see Output Coupling
Capacitor section). Leave the unused output floating.
Power Dissipation
Under normal operating conditions, linear power amplifiers like the MAX4366/MAX4367/MAX4368 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:
PDISS(MAX) =
TJ(MAX) - TA
Θ JA
where TJ(MAX) is +150°C and TA is the reciprocal of the
derating factor in °C/W as specified in the Absolute
Single-Ended Configuration
The MAX4366/MAX4367/MAX4368 can be used as single-ended amplifiers (Figure 2). The gain of the device
in single-ended mode is 1/2 the gain in BTL configuration and the output power is reduced by a factor of 4.
The single-ended gains of the MAX4367 and MAX4368
are 1V/V and 1.5V/V, respectively. Set the MAX4366
gain according to the Gain-Setting Resistors section.
OUT+
5
COUT
MAX4367
OUT-
8
Figure 2. MAX4367 Single-Ended Configuration
VCC
6
CLICKLESS/
POPLESS
SHUTDOWN
CONTROL
VCC
50kΩ
2
SHDN
1
OUT-
8
BIAS
CBIAS
50kΩ
3
IN+
10kΩ
10kΩ
OUT+ 5
CIN
RIN
AUDIO INPUT
4
INMAX4366
GND
7
RF
Figure 3. MAX4366 Typical Application Circuit
10
______________________________________________________________________________________
RL
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
6
CLICKLESS/
POPLESS
SHUTDOWN
CONTROL
VCC
50kΩ
2
1
OUT-
8
OUT+
5
BIAS
CBIAS
50kΩ
3
CIN
AUDIO
INPUT
SHDN
4
10kΩ
IN+
IN-
10kΩ
RIN
RF
MAX4367
MAX4368
GND
7
MAX4367: RIN = RF = 20kΩ
MAX4368: RIN = 20kΩ, RF = 30kΩ
PIN NUMBERS REFER TO SOT23, QFN, AND µMAX PACKAGES
Figure 4. MAX4367/MAX4368 Typical Application Circuit
Maximum Ratings section. For example, ΘJA of a µMAX
package is 222°C/W.
The increase in power delivered by the BTL configuration directly results in an increase in internal power dissipation over the single-ended configuration. If the
power dissipation exceeds the maximum allowed for a
given package, either reduce V CC , increase load
impedance, decrease the ambient temperature, or add
heat sinking to the device. Large output, supply, and
ground traces improve the maximum power dissipation
in the package.
Thermal overload protection limits total power dissipation in the MAX4366/MAX4367/MAX4368. When the
junction temperature exceeds +165°C, the thermal protection circuitry disables the amplifier output stage. The
amplifiers are re-enabled once the junction temperature
cools by +10°C. This results in a pulsing output under
continuous thermal overload conditions avoiding damage to the port.
Component Selection
Gain-Setting Resistors
External feedback components set the gain of the
MAX4366. Resistors RF and RIN (Figure 3) set the gain
of the input amplifier as follows:
R 
A VD = 2  F 
 RIN 
The gain of the device in a single-ended configuration
is half the gain of the BTL case. Choose RF between
10kΩ and 50kΩ. The gains of the MAX4367/MAX4368
are set internally (Figure 4).
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:
ƒ -3dB =
1
2πRINCIN
______________________________________________________________________________________
11
MAX4366/MAX4367/MAX4368
VCC
MAX4366/MAX4367/MAX4368
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
Choose RIN according to the Gain-Setting Resistors
section. Choose the 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 system.
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 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.
BIAS Capacitor
The BIAS bypass capacitor, CBIAS improves powersupply rejection ratio and THD + N by reducing powersupply noise at the common-mode bias node, and
serves as the primary click-and-pop 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 clickand-pop suppression is given by:
C R 
CBIAS ≤ 10  IN IN 
 25kΩ 
In addition, a larger CBIAS value yields higher PSRR,
especially in single-ended applications.
Output-Coupling Capacitor
The MAX4366/MAX4367/MAX4368 require output-coupling capacitors only when configured as a singleended amplifier. The output capacitor blocks the DC
component of the amplifier output, preventing DC current flowing to the load. The output capacitor and the
load impedance form a highpass filter with the -3dB
point determined by:
ƒ -3dB =
1
2πRLCOUT
As with the input capacitor, choose the output capacitor
(COUT) such that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the lowfrequency response of the system.
12
TIP
(SIGNAL)
SLEEVE
(GND)
Figure 5. Typical 2-Wire Headphone Plug
In addition to click-and-pop suppression and frequency
band considerations, the load impedance is another
concern when choosing COUT. Load impedance can
vary, changing the -3dB point of the output filter. A
lower impedance increases the corner frequency,
degrading low-frequency response. Select COUT such
that the worst-case load/COUT combination yields an
adequate response.
Clickless/Popless Operation
Proper selection of AC-coupling capacitors and CBIAS
achieves clickless/popless shutdown and startup. The
value of CBIAS determines the rate at which the mid-rail
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, improving click-and-pop suppression.
Supply Bypassing
Proper supply bypassing ensures low-noise, low-distortion performance. Place a 0.1µF ceramic capacitor in parallel with a 10µF capacitor from VCC to GND. Locate the
bypass capacitors as close to the device as possible.
Headphone Applications
The MAX4366/MAX4368 can drive a mono headphone
when configured as a single-ended amplifier. Typical 2wire headphone plugs consist of a tip and sleeve. The tip
is the signal carrier while the sleeve is the ground connection (Figure 5). Figure 6 shows the device configured
to drive headphones. OUT+ is connected to the tip,
delivering the signal to the headphone, while OUTremains unconnected.
______________________________________________________________________________________
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
OUT+
MAX4366
MAX4367
MAX4368
5
HEADPHONE JACK
COUT
OUT-
8
MAX4366
MAX4367
MAX4368
COUT
EARBUD SPEAKER
JACK
OUT-
INTERNAL
LOUDSPEAKER
Figure 6. MAX4367 Headphone Application Circuit
Figure 7. Headset with Internal Speaker Application Circuit
tion passes the audio signal unattenuated. Setting the
wiper to the lowest position fully attenuates the input.
Use the 100kΩ version of the MAX5160.
AUDIO
INPUT
3 H
MAX5160
OUT+
W 5
6 L
4
CIN
5
IN- MAX4367
MAX4368
OUT-
8
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 surfacemount components and placing external components
as close to the device as possible.
UCSP Considerations
Figure 8. MAX4367/MAX5160 Volume Control Circuit
For general UCSP information and PC layout considerations, please refer to the Maxim Application Note:
Wafer-Level Ultra Chip-Scale Package.
Wireless-Phone Headset Application
Many wireless telephones feature an earbud speaker/inline microphone combination for hands-free use. One
common solution is to use a BTL amplifier that drives the
internal speaker and an earplug jack that mutes the internal speaker by physically disconnecting OUT- when a
headset is plugged in (Figure 7). The headset is driven
single-endedly, requiring an output-coupling capacitor,
COUT, and resulting in a 4x reduction in output power.
Adding Volume Control
The addition of a digital potentiometer provides simple
volume control. Figure 8 shows the MAX4367/MAX4368
with the MAX5160 digital potentiometer used as an
input attenuator. Connect the high terminal of the
MAX5160 to the audio input, the low terminal to ground
and the wiper to CIN. Setting the wiper to the top posi-
______________________________________________________________________________________
13
MAX4366/MAX4367/MAX4368
OUT+
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
MAX4366/MAX4367/MAX4368
Pin Configurations (continued)
Ordering Information (continued)
PART
TOP VIEW
SHDN 1
BIAS 2
IN+
3
IN- 4
MAX4366
MAX4367
MAX4368
TEMP RANGE
PIN/BUMPPACKAGE
MAX4367EBL-T* -40°C to +85°C
8 UCSP-8
AAL
MAX4367EKA-T -40°C to +85°C
8 SOT23-8
AAIP
8
OUT-
MAX4367EUA
-40°C to +85°C
8 µMAX
7
GND
MAX4367ETA
-40°C to +85°C
6
VCC
5
OUT+
SOT23/µMAX/QFN
TOP
MARK
—
8 Thin QFN-EP**
AAB
MAX4368EBL-T* -40°C to +85°C
8 UCSP-8
AAM
MAX4368EKA-T -40°C to +85°C
8 SOT23-8
AAIQ
MAX4368EUA
-40°C to +85°C
8 µMAX
MAX4368ETA
-40°C to +85°C
8 Thin QFN-EP**
—
AAA
*Future product—contact factory for availability.
**EP = Exposed paddle.
Selector Guide
14
PART
GAIN
MAX4366
External
MAX4367
2V/V
MAX4368
3V/V
______________________________________________________________________________________
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
VCC
VCC
50kΩ
50kΩ
MAX4366
MAX4367
MAX4368
BIAS
BIAS
SHDN
CLICKLESS/
POPLESS
SHUTDOWN
CONTROL
OUT-
50kΩ
10kΩ
IN+
10kΩ
IN+
SHDN
OUT-
50kΩ
CLICKLESS/
POPLESS
SHUTDOWN
CONTROL
10kΩ
10kΩ
OUT+
OUT+
IN-
IN20kΩ
RF*
GND
*RF = 30kΩ (MAX4368)
RF = 20kΩ (MAX4367)
GND
Chip Information
TRANSISTOR COUNT: 669
PROCESS: Bipolar
______________________________________________________________________________________
15
MAX4366/MAX4367/MAX4368
Functional Diagrams
Package Information
SOT23, 8L.EPS
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
4X S
8
E
ÿ 0.50±0.1
8
INCHES
DIM
A
A1
A2
b
H
c
D
e
E
H
0.6±0.1
1
L
1
α
0.6±0.1
S
BOTTOM VIEW
D
MIN
0.002
0.030
MAX
0.043
0.006
0.037
0.010
0.014
0.005
0.007
0.116
0.120
0.0256 BSC
0.116
0.120
0.188
0.198
0.016
0.026
6∞
0∞
0.0207 BSC
8LUMAXD.EPS
MAX4366/MAX4367/MAX4368
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
MILLIMETERS
MAX
MIN
0.05
0.75
1.10
0.15
0.95
0.25
0.36
0.13
0.18
2.95
3.05
0.65 BSC
2.95
3.05
4.78
5.03
0.41
0.66
0∞
6∞
0.5250 BSC
TOP VIEW
A1
A2
e
FRONT VIEW
A
α
c
b
L
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0036
16
REV.
J
______________________________________________________________________________________
1
1
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
6, 8, &10L, QFN THIN.EPS
PACKAGE OUTLINE, 6, 8 & 10L,
QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
21-0137
C
COMMON DIMENSIONS
SYMBOL
A
MIN.
0.70
0.80
D
2.90
MAX.
3.10
E
2.90
3.10
A1
0.00
0.05
L
k
0.20
0.40
0.25 MIN
A2
0.20 REF.
PACKAGE VARIATIONS
PKG. CODE
N
D2
E2
e
JEDEC SPEC
b
T633-1
6
1.50±0.10
2.30±0.10
0.95 BSC
MO229 / WEEA
0.40±0.05
1.90 REF
T833-1
8
1.50±0.10
2.30±0.10
0.65 BSC
MO229 / WEEC
0.30±0.05
1.95 REF
T1033-1
10
1.50±0.10
2.30±0.10
0.50 BSC
MO229 / WEED-3
0.25±0.05
2.00 REF
[(N/2)-1] x e
PACKAGE OUTLINE, 6, 8 & 10L,
QFN THIN (DUAL), EXPOSED PAD, 3x3x0.80 mm
21-0137
C
______________________________________________________________________________________
17
MAX4366/MAX4367/MAX4368
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
9LUCSP, 3x3.EPS
MAX4366/MAX4367/MAX4368
330mW, Ultra-Small, Audio Power Amplifiers
with Shutdown
Note: Bump B2 is not present.
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.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2002 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.