XX-XXXX; Rev 0; 3/08
20W Stereo Class D Speaker Amplifier
with Volume Control
MAX974
General Description
Features
The MAX9744 20W stereo Class D audio power amplifi-
er provides Class AB amplifier performance with Class
D efficiency, conserving board space and eliminating
the need for a bulky heatsink. This device features sin-
gle-supply operation, adjustable gain, shutdown mode,
SYNC output, speaker mute, and industry-leading click-
and-pop suppression.
♦ Wide 4.5V to 14V Power-Supply Voltage Range
♦ Filterless Spread-Spectrum Modulation Lowers
Radiated RF Emissions from Speaker Cables
♦ 20W Stereo Output (4Ω, V
= 12V, THD+N = 10%)
DD
2
♦ Integrated Volume Control (I C or Analog)
♦ Low 0.04% THD+N
The MAX9744 features a 64-step dual-mode (analog or
digital), programmable volume control and mute func-
tion. The MAX9744 operates from a 4.5V to 14V single
supply and can deliver up to 20W per channel into a
4Ω speaker with a 14V supply.
The MAX9744 offers two modulation schemes: a fixed-
frequency modulation mode that allows one of several
preset switching frequencies to be selected, and a
spread-spectrum modulation mode that helps to
reduce EMI-radiated emissions.
♦ High 75dB PSRR
♦ High 93% Efficiency (20W, 8Ω)
♦ Integrated Click-and-Pop Suppression
♦ Low-Power Shutdown Mode
♦ Short-Circuit and Thermal-Overload Protection
♦ Available in a 44-Pin Thin QFN-EP
(7mm x 7mm x 0.8mm)
The MAX9744 features high 75dB PSRR, low 0.04%
THD+N, and SNR in excess of 90dB. Robust short-cir-
cuit and thermal-overload protection prevent device
damage during a fault condition. The MAX9744 is avail-
able in a 44-pin thin QFN-EP (7mm x 7mm x 0.8mm)
package and is specified over the extended -40°C to
+85°C temperature range.
Ordering Information
PIN-
PACKAGE
PKG
CODE
PART
TEMP RANGE
MAX9744ETH+
-40°C to +85°C 44 TQFN-EP*
T4477-3
Applications
+Denotes a lead-free package.
*EP = Exposed paddle.
Flat-Panel Televisions
PC Speaker Systems
Multimedia Docking Stations
Pin Configuration appears at end of data sheet.
Simplified Block Diagram
3V TO 3.6V
4.5V TO 14V
MAX9744 EMI WITH FERRITE BEAD FILTERS
MAX9744
(V = 12V, 1m CABLE, 8Ω LOAD)
DD
40
35
30
25
20
15
10
5
VOLUME
CONTROL
BIAS
OVER 20dB MARGIN
TO EN55022 B LIMIT
MUTE
SHUTDOWN
CONTROL
2
I C
ANALOG
CONTROL
0
SYNC
SYNCOUT
30
80
120 160 200 240 280
140 260 300
FREQUENCY (MHz)
OSCILLATOR
60
100
180
220
________________________________________________________________ Maxim Integrated Products
1
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.