19-1746; Rev 3; 3/05
Mono, 2W, Switch-Mode (Class D)
Audio Power Amplifier
General Description
The MAX4295 mono, switch-mode (Class D) audio
power amplifier operates from a single +2.7V to +5.5V
supply. The MAX4295 has >85% efficiency and is
capable of delivering 2W continuous power to a 4Ω
load, making it ideal for portable multimedia and gener-
al-purpose high-power audio applications.
The MAX4295 features a total harmonic distortion plus
noise (THD+N) of 0.4% (f
OSC
= 125kHz), low quiescent
current of 2.8mA, high efficiency, and clickless power-
up and shutdown. The
SHDN
input disables the device
and limits supply current to <1.5µA. Other features
include a 1A current limit, thermal protection, and
undervoltage lockout.
The MAX4295 reduces the number of required external
components. Internal high-speed power-MOS transis-
tors allow operation as a bridge-tied load (BTL) amplifi-
er. The BTL configuration eliminates the need for
isolation capacitors on the output. The frequency-selec-
table pulse-width modulator (PWM) allows the user to
optimize the size and cost of the output filter.
The MAX4295 is offered in a space-saving 16-pin
QSOP or narrow SO package.
Features
♦
+2.7V to +5.5V Single-Supply Operation
♦
2W/Channel Output Power at 5V
0.7W/Channel Output Power at 3V
♦
87% Efficiency (R
L
= 4Ω, P
OUT
= 2W)
♦
0.4% THD+N (R
L
= 4Ω, f
OSC
= 125kHz)
♦
Logic-Programmable PWM Frequency Selection
(125kHz, 250kHz, 500kHz, 1MHz)
♦
Low-Power Shutdown Mode
♦
Clickless Transitions Into and Out of Shutdown
♦
1A Current Limit and Thermal Protection
♦
Available in Space-Saving Packages
16-Pin QSOP or Narrow SO
MAX4295
Ordering Information
PART
MAX4295EEE
MAX4295ESE
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 Narrow SO
Applications
Palmtop/Notebook
Computers
PDA Audio
Sound Cards
Game Cards
Boom Boxes
AC Amplifiers
Battery-Powered Speakers
Cordless Phones
Portable Equipment
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
R
F
AUDIO
INPUT
C
IN
AOUT
R
IN
IN
OUT+
OUT-
PV
CC
PV
CC
PGND
PGND
2.7V TO 5.5V
MAX4295
2.7V TO 5.5V
V
CC
GND
GND
VCM
ON
OFF
SHDN
FS1
FS2
SS
________________________________________________________________
Maxim Integrated Products
1
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.
Mono, 2W, Switch-Mode (Class D)
Audio Power Amplifier
MAX4295
ABSOLUTE MAXIMUM RATINGS
V
CC
, PV
CC
to GND or PGND....................................-0.3V to +6V
PGND to GND.....................................................................±0.3V
PV
CC
to V
CC
.......................................................................±0.3V
VCM, SS, AOUT, IN to GND .......................-0.3V to (V
CC
+ 0.3V)
SHDN,
FS1, FS2 to GND ..........................................-0.3V to +6V
OUT_ to PGND .........................................-0.3V to (PV
CC
+ 0.3V)
Op Amp Output Short-Circuit
Duration (AOUT).........Indefinite Short Circuit to Either Supply
H-Bridge Short-Circuit
Duration (OUT_) ................Continuous Short Circuit to PGND,
PV
CC
or between OUT+ and OUT-
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.30mW/°C above +70°C)........667mW
16-Pin Narrow SO (derate 8.7mW/°C above +70°C)......696mW
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
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
(V
CC
= PV
CC
= +5V,
SHDN
= V
CC
, FS1 = GND, FS2 = V
CC
(f
OSC
= 250kHz), input amplifier gain = -1V/V, T
A
= T
MIN
to T
MAX
, unless
otherwise noted. Typical values are T
A
= +25°C.) (Note 1)
PARAMETER
GENERAL
Supply Voltage Range
Quiescent Supply Current
Shutdown Supply Current
Voltage at VCM Pin
FS1 = GND, FS2 = GND
PWM Frequency
FS1 = GND, FS2 = V
CC
FS1 = V
CC
, FS2 = GND
FS1 = V
CC
, FS2 = V
CC
PWM Frequency Change with
V
CC
Duty Cycle
Duty Cycle Change with V
CC
Switch On-Resistance
(each power device)
H-Bridge Output Leakage
H-Bridge Current Limit
Soft-Start Capacitor Charging
Current
Undervoltage Lockout
Thermal Shutdown Trip Point
V
SS
= 0V
0.75
1.8
V
CC
= 2.7V to 5.5V
V
IN
= 0.06
×
V
CC
V
IN
= 0.30
×
V
CC
V
IN
= 0.54
×
V
CC
V
IN
= 0.3
×
V
CC
, V
CC
= 2.7V to 5.5V
I
OUT
= 150mA
SHDN
= GND
V
CC
= 5V
V
CC
= 2.7V
10.2
49.2
86.2
(Note 2)
Output load not connected
SHDN
= GND
0.285
×
V
CC
105
210
420
840
2.7
2.8
1.5
0.3
×
V
CC
125
250
500
1000
±1
12
50
88
±0.02
0.25
0.35
0
1
1.35
2.2
145
1.95
2.6
5.5
4
8
0.315
×
V
CC
145
290
580
1160
±3
13.8
50.8
89.8
±0.15
0.5
1.0
±5
%/V
Ω
µA
A
µA
V
°C
%
kHz/V
kHz
V
mA
µA
V
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Mono, 2W, Switch-Mode (Class D)
Audio Power Amplifier
MAX4295
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= PV
CC
= +5V,
SHDN
= V
CC
, FS1 = GND, FS2 = V
CC
(f
OSC
= 250kHz), input amplifier gain = -1V/V, T
A
= T
MIN
to T
MAX
, unless
otherwise noted. Typical values are T
A
= +25°C.)
PARAMETER
Input Voltage Range
V
CC
= +3V, f
IN
= 1kHz
Maximum Output Power
V
CC
= +5V, f
IN
= 1kHz
Total Harmonic Distortion Plus
Noise
Efficiency
Logic Input Current
Logic Input High Voltage
Logic Input Low Voltage
INPUT AMPLIFIER
Input Offset Voltage
V
OS
Temp Coefficient
Input Bias Current
Input Noise-Voltage Density
Input Capacitance
Output Resistance
AOUT Disabled Mode Leakage
Current
Short-Circuit Current
Large-Signal Voltage Gain
AOUT Voltage Swing
Gain-Bandwidth Product
Power-Supply Rejection
Maximum Capacitive Load
V
CC
= +2.7V to +5.5V
No sustained oscillations
66
SHDN
= GND, V
AOUT
= 0 to V
CC
AOUT to GND
AOUT to V
CC
V
OUT
= 0.2V to 4.6V, R
L(OPAMP)
= 10kΩ
V
DIFF
≥
10mV,
R
L(OPAMP)
= 10kΩ
V
CC
- V
OH
V
OL
78
(Note 3)
f = 10kHz
±0.5
±5
±0.05
32
2.5
0.01
±0.1
8
65
115
40
40
1.25
90
200
250
100
±1
±25
±4
mV
µV/°C
nA
nV/√Hz
pF
Ω
µA
mA
dB
mV
MHz
dB
pF
R
L
= 8Ω
R
L
= 4Ω
R
L
= 8Ω
R
L
= 4Ω
CONDITIONS
MIN
TYP
0 to 0.6
x V
CC
0.4
0.7
1.2
2
0.4
87
1
0.7
×
V
CC
0.3
×
V
CC
100
%
%
nA
V
V
W
MAX
UNITS
V
R
L
= 4Ω, f
IN
= 1kHz, P
O
= 1W, f
OSC
= 125kHz
MAX4295, R
L
= 4Ω, f
IN
= 1kHz, P
O
= 2W
V
LOGIC
= 0 to V
CC
LOGIC INPUTS (SHDN, FS1, FS2)
Note 1:
All devices are 100% production tested at T
A
= 25°C. All temperature limits are guaranteed by design.
Note 2:
Supply Voltage Range guaranteed by PSRR of input amplifier, frequency, duty cycle, and H-bridge on-resistance.
Note 3:
Guaranteed by design, not production tested.
_______________________________________________________________________________________
3
Mono, 2W, Switch-Mode (Class D)
Audio Power Amplifier
MAX4295
Typical Operating Characteristics
(V
CC
= PV
CC
= +3V, input amplifier gain = -1,
SHDN
= V
CC
, T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT FREQUENCY (V
IN
= 2.5V
P-P
)
MAX4295 toc01
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT FREQUENCY (V
IN
= 2.5V
P-P
)
MAX4295 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT FREQUENCY (V
IN
= 2.5V
P-P
)
V
CC
= +5V
R
L
= 32Ω
MAX4295 toc03
10
V
CC
= +5V
R
L
= 4Ω
1MHz
125kHz
10
V
CC
= +5V
R
L
= 8Ω
1MHz
125kHz
10
1
THD+N (%)
THD+N (%)
1
THD+N (%)
1
1MHz
125kHz
0.1
500kHz
250kHz
0.1
500kHz
250kHz
0.1
500kHz
250kHz
0.01
10
1k
INPUT FREQUENCY (Hz)
100k
0.01
10
1k
INPUT FREQUENCY (Hz)
100k
0.01
10
1k
INPUT FREQUENCY (Hz)
100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 1kHz)
MAX4295 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 1kHz)
MAX4295 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 1kHz)
V
CC
= +5V
R
L
= 32Ω
500kHz
MAX4295 toc06
100
V
CC
= +5V
R
L
= 4Ω
1MHz
100
100
V
CC
= +5V
R
L
= 8Ω
10
THD+N (%)
THD+N (%)
10
THD+N (%)
125kHz
1MHz
1
10
1
250kHz
125kHz
500kHz
1
1MHz
250kHz
0.1
0.1
0.1
500kHz 250kHz
125kHz
0.10
0
0.3
0.6
0.9
1.2
1.5
1.8
0
0.1
0.2
0.3
0.4
0.5
OUTPUT POWER (W)
OUTPUT POWER (W)
0.10
0
0.5
1.0
1.5
2.0
2.5
OUTPUT POWER (W)
0.10
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 20kHz)
MAX4295 toc07
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 20kHz)
MAX4295 toc08
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 20kHz)
V
CC
= +5V
R
L
= 32Ω
1MHz
MAX4295 toc09
100
V
CC
= +5V
R
L
= 4Ω
10
V
CC
= +5V
R
L
= 8Ω
100
1MHz
10
1
THD+N (%)
1MHz
1
125kHz
250kHz
0.1
500kHz
500kHz
0.10
0
0.5
1.0
1.5
2.0
2.5
OUTPUT POWER (W)
0.01
0
0.3
0.6
0.9
1.2
1.5
1.8
OUTPUT POWER (W)
THD+N (%)
125kHz
THD+N (%)
10
1
125kHz
0.1
250kHz
500kHz
0.1
250kHz
0.10
0
0.1
0.2
0.3
0.4
0.5
OUTPUT POWER (W)
4
_______________________________________________________________________________________
Mono, 2W, Switch-Mode (Class D)
Audio Power Amplifier
MAX4295
Typical Operating Characteristics (continued)
(V
CC
= PV
CC
= +3V, input amplifier gain = -1,
SHDN
= V
CC
, T
A
= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT FREQUENCY (V
IN
= 1.5V
P-P
)
MAX4295 toc10
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT FREQUENCY (V
IN
= 1.5V
P-P
)
MAX4295 toc11
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT FREQUENCY (V
IN
= 1.5V
P-P
)
V
CC
= +3V
R
L
= 32Ω
1MHz
1
THD+N (%)
125kHz
MAX4295 toc12
10
125kHz 1MHz
1
THD+N (%)
500kHz
0.1
V
CC
= +3V
R
L
= 4Ω
10
1MHz
125kHz
1
THD+N (%)
V
CC
= +3V
R
L
= 8Ω
10
250kHz
0.1
500kHz
250kHz
0.1
250kHz
500kHz
0.01
10
1k
INPUT FREQUENCY (Hz)
100k
0.01
10
1k
INPUT FREQUENCY (Hz)
100k
0.01
10
1k
INPUT FREQUENCY (Hz)
100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 1kHz)
MAX4295 toc13
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 1kHz)
MAX4295 toc14
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 1kHz)
V
CC
= +3V
R
L
= 32Ω
1MHz
10
THD+N (%)
MAX4295 toc15
100
V
CC
= +3V
R
L
= 4Ω
1MHz
100
V
CC
= +3V
R
L
= 8Ω
100
1MHz
10
THD+N (%)
500kHz
1
125kHz
10
THD+N (%)
250kHz
500kHz
1
0.1
125kHz
0.1
0
0.1
0.2
0.3
0.4
0.5
0.6 0.7
0.8
OUTPUT POWER (W)
0.10
0
0.1
0.2
0.3
0.4
0.5
0.6 0.7
0.8
OUTPUT POWER (W)
0.10
0
0.05
0.10
0.15
0.20
OUTPUT POWER (W)
250kHz
0.1
250kHz
500kHz
1
125kHz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 20kHz)
MAX4295 toc16
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 20kHz)
MAX4295 toc17
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (f
IN
= 20kHz)
V
CC
= +3V
R
L
= 32Ω
1MHz
MAX4295 toc18
100
V
CC
= +3V
R
L
= 4Ω
1MHz
250kHz
100
V
CC
= +3V
R
L
= 8Ω
1MHz
100
10
THD+N (%)
THD+N (%)
10
125kHz
1
10
THD+N (%)
1
500kHz
0.1
125kHz
1
125kHz
0.1
250kHz
500kHz
500kHz
0.1
250kHz
0.10
0
0.1
0.2
0.3
0.4
0.5
0.6 0.7
0.8
OUTPUT POWER (W)
0.10
0
0.1
0.2
0.3
0.4
0.5
0.6 0.7
0.8
OUTPUT POWER (W)
0.10
0
0.05
0.10
0.15
0.20
OUTPUT POWER (W)
_______________________________________________________________________________________
5
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