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PDF MAX4297 Data sheet ( Hoja de datos )
| Número de pieza | MAX4297 | |
| Descripción | Mono/Stereo 2W Switch-Mode (Class-D) Audio Power Amplifiers | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-1746; Rev 1; 2/01
Mono/Stereo 2W Switch-Mode (Class-D)
Audio Power Amplifiers
General Description
The MAX4295/MAX4297 mono/stereo, switch-mode
(Class-D) audio power amplifiers operate from a single
+2.7V to +5.5V supply. They have >85% efficiency and
are capable of delivering 2W continuous power to a 4Ω
load, making them ideal for portable multimedia and
general-purpose high-power audio applications.
The MAX4295/MAX4297 feature a total harmonic distor-
tion plus noise (THD+N) of 0.4% (fOSC = 125kHz), low
quiescent current of 2.8mA (MAX4295) or 4.6mA
(MAX4297), high efficiency, and clickless power-up and
shutdown. The SHDN input disables the device and lim-
its supply current to <1.5µA (MAX4295) or <2.3µA
(MAX4297). Other features include a 1A current limit,
thermal protection, and under-voltage lockout.
The MAX4295 (mono) and MAX4297 (stereo) reduce
the number of required external components. Both
devices have internal high-speed power-MOS transis-
tors, allowing operation as bridge-tied load (BTL) ampli-
fiers. 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 package, and the MAX4297 is offered in a com-
pact 24-pin SSOP package.
Applications
Palmtop/Notebook
Computers
PDA Audio
Sound Cards
Game Cards
Boom Boxes
AC Amplifiers
Battery-Powered Speakers
Cordless Phones
Portable Equipment
Features
o +2.7V to +5.5V Single-Supply Operation
o 2W/Channel Output Power at 5V
0.7W/Channel Output Power at 3V
o 87% Efficiency (RL = 4Ω, PO = 2W, MAX4295)
o 0.4% THD+N (RL = 4Ω, fOSC = 125kHz)
o Logic-Programmable PWM Frequency Selection
(125kHz, 250kHz, 500kHz, 1MHz)
o Low-Power Shutdown Mode
o Clickless Transitions Into and Out of Shutdown
o 1A Current Limit and Thermal Protection
o Available in Space-Saving Packages
16-Pin QSOP (MAX4295)
24-Pin SSOP (MAX4297)
PART
MAX4295EEE
MAX4295ESE
MAX4297EAG
MAX4297EWG
Ordering Information
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 Narrow SO
24 SSOP
24 Wide SO
Pin Configurations appear at end of data sheet.
Typical Operating Circuit
INPUTL
CIN RIN
INPUTR
CIN RIN
VCC
VCC
VCC VPVCC
RF 1 AOUTL
2 INL
RF 12 AOUTR
11
INR
22 SHDN
14 FS1
15
FS2
SS
24
CSS
4, 9,
3 16, 21
VCC VPVCC
+
MAX4297
OUT+L 5
OUT-L 20
L1A
C1A
L1B
C1B
8
OUT+R
L2A
C2A
OUT-R 17
VCM* 13
L2B
C2B
AGND
10
PGND
6, 7,
18, 19
*DO NOT CONNECT.
________________________________________________________________ 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.
1 page  
Mono/Stereo 2W Switch-Mode (Class-D)
Audio Power Amplifiers
Typical Operating Characteristics (continued)
(VCC = PVCC = +3V, input amplifier gain = -1, SHDN = VCC , TA = +25°C, unless otherwise noted.)
MAX4295
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT FREQUENCY (VIN = 1.5Vp-p)
10 VCC = +3V
RL = 4Ω
125kHz 1MHz
MAX4295
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT FREQUENCY (VIN = 1.5Vp-p)
10 VCC = +3V
RL = 8Ω
1MHz
125kHz
MAX4295
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. INPUT FREQUENCY (VIN = 1.5Vp-p)
10
VCC = +3V
RL = 32Ω
1MHz
125kHz
1 11
500kHz
0.1
250kHz
500kHz
0.1
250kHz
0.1
250kHz
500kHz
0.01
10
1k
INPUT FREQUENCY (Hz)
100k
MAX4295
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (fIN = 1kHz)
100
VCC = +3V
RL = 4Ω
1MHz
10
250kHz
500kHz
1
125kHz
0.01
10
1k
INPUT FREQUENCY (Hz)
100k
MAX4295
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (fIN = 1kHz)
100
VCC = +3V
RL = 8Ω
1MHz
10
500kHz
1
125kHz
0.1 250kHz
0.01
10
1k
INPUT FREQUENCY (Hz)
100k
MAX4295
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (fIN = 1kHz)
100
VCC = +3V
RL = 32Ω
1MHz
10
500kHz
1
125kHz
0.1
250kHz
0.1
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7
OUTPUT POWER (W)
0.8
MAX4295
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (fIN = 20kHz)
100
VCC = +3V
RL = 4Ω
1MHz
10
250kHz
1
500kHz
0.1 125kHz
0.10
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7
OUTPUT POWER (W)
0.8
0.10
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7
OUTPUT POWER (W)
0.8
MAX4295
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (fIN = 20kHz)
100
VCC = +3V
RL = 8Ω
10 1MHz
125kHz
1
500kHz
0.1
250kHz
0.10
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7
OUTPUT POWER (W)
0.8
0.10
0
0.05 0.10 0.15
OUTPUT POWER (W)
0.20
MAX4295
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (fIN = 20kHz)
100
VCC = +3V
RL = 32Ω
10 1MHz
1
0.1
0.10
0
125kHz
250kHz
500kHz
0.05 0.10 0.15
OUTPUT POWER (W)
0.20
_______________________________________________________________________________________ 5
5 Page 
Mono/Stereo 2W Switch-Mode (Class-D)
Audio Power Amplifiers
AOUT
IN
0.3 ✕ VCC
(VCM)
FS1
FS2
SS
CSS
PWM
OSC
POWER MANAGEMENT
AND PROTECTION
VCC
GND
PVCC
GATE
DRIVE
OUT+
PGND
PVCC
GATE
DRIVE
OUT-
PGND
Figure 1a. MAX4295 Functional Diagram
H-bridge. The switches work in pairs to reverse the
polarity of the signal in the load. Break-before-make
switching of the H-bridge MOSFETs by the driver circuit
keeps supply current glitches and crowbar current in
the MOSFETs at a low level. The output swing of the H-
bridge is a direct function of the supply voltage.
Varying the oscillator swing in proportion to the supply
voltage maintains constant gain with varying supply
voltage.
FS1 and FS2 program the oscillator to a frequency of
125kHz, 250kHz, 500kHz, and 1MHz. The sawtooth
oscillator swings between GND and 0.6 ✕ VCC. The
input signal is typically AC-coupled to the internal input
op amp, whose gain can be controlled through external
feedback components. The common-mode voltage of
the input amplifier is 0.3 ✕ VCC and is internally gener-
ated from the same resistive divider used to generate
the 0.6 ✕ VCC reference for the PWM oscillator.
Current Limit
A current-limiting circuit in the H-bridge monitors the
current in the H-bridge transistors and disables the H-
bridge if the current in any of the H-bridge transistors
exceeds 1A. The H-bridge is enabled after a period of
100µs. A continuous short circuit at the output results in
a pulsating output.
Thermal Overload Protection
Thermal overload protection limits total power dissipa-
tion in the MAX4295/MAX4297. When the junction tem-
perature exceeds +145°C, the thermal detection
disables the H-bridge transistors. The H-bridge transis-
tors are enabled after the IC’s junction temperature
cools by 10°C. This results in a pulsating output under
continuous thermal overload conditions. Junction tem-
perature does not exceed the thermal overload trip
point in normal operation, but only in the event of fault
conditions, such as when the H-bridge outputs are
short circuited.
Undervoltage Lockout
At low supply voltages, the MOSFETs in the H-bridge
may have inadequate gate drive thus dissipating
excessive power. The undervoltage lockout circuit pre-
vents the device from operating at supply voltages
below +2.2V.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet MAX4297.PDF ] | |
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