MAX9736AETJ/V+ Maxim Integrated Products, MAX9736AETJ/V+ Datasheet - Page 14

• Manufacturer Part Number: MAX9736AETJ/V+
• Description: IC AMP MONO/STER CLASS D 32TQFN
• Manufacturer: Maxim Integrated Products
• Type: Class Dr

Specifications of MAX9736AETJ/V+

• Output Type: 1-Channel (Mono) or 2-Channel (Stereo)
• Max Output Power X Channels @ Load: 35W x 1 @ 4 Ohm; 17.5W x 2 @ 8 Ohm
• Voltage - Supply: 8 V ~ 28 V
• Features: Depop, Short-Circuit and Thermal Protection, Shutdown
• Mounting Type: Surface Mount
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Mono/Stereo High-Power Class D Amplifier
The MAX9736A/B/D filterless, stereo Class D audio
power amplifiers offer Class AB performance and Class
D efficiency with minimal board space. The MAX9736A
outputs 2x15W in stereo mode and 30W in mono mode.
The MAX9736B/D output 2x6W in stereo mode and 12W
in mono mode. These devices operate from an 8V to
28V supply range.
The MAX9736 features a filterless, spread-spectrum
switching mode (MOD = high) or a classic PWM fixed-
frequency switching mode (MOD = low).
The MAX9736 features externally set gain and a low-
power shutdown mode that reduces supply current to
less than 1µA. Comprehensive click-and-pop circuitry
minimizes noise into and out of shutdown or mute.
The MAX9736 features two output modulation schemes,
filterless modulation (MOD = high) or classic PWM (MOD
= low). Maxim’s unique, filterless modulation scheme
eliminates the LC filter required by traditional Class D
amplifiers, reducing component count, conserving
board space, and reducing system cost. Configure for
classic PWM output when using a full LC filter.
Click-and-pop protection does not apply when the out-
put is switching between modulation schemes. To
maintain click-and-pop protection when switching
between output schemes the device must enter shut-
down mode and be configured to the new output
scheme before the startup sequence is finished.
The MAX9736 features a unique spread-spectrum mode
that flattens the wideband spectral components, improv-
ing EMI radiated by the speaker and cables. The
switching frequency of the Class D amplifier varies ran-
domly by ±6kHz around the 300kHz center frequency.
Instead of a large amount of spectral energy present at
multiples of the switching frequency, the energy is
spread over a bandwidth that increases with frequency.
Above a few megahertz, the wideband spectrum looks
like white noise for EMI purposes. A proprietary amplifier
topology ensures this white noise does not corrupt the
noise floor in the audio bandwidth. The spread-spec-
trum mode is enabled only with filterless modulation.
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Filterless Modulation/PWM Modulation
Detailed Description
Spread-Spectrum Mode
Operating Modes
The high efficiency of a Class D amplifier is due to the
switching operation of the output stage transistors. In a
Class D amplifier, the output transistors act as switches
and consume negligible power. Power loss associated
with the Class D output stage is due to the I
the MOSFET on-resistance, various switching losses,
and quiescent current overhead.
The theoretical best efficiency of a linear amplifier is 78%
at peak output power. Under typical music reproduction
levels, the efficiency falls below 30%, whereas the
MAX9736 exhibits > 80% efficiency under the same con-
ditions (Figure 1).
The MAX9736 features a shutdown mode that reduces
power consumption and extends battery life in portable
applications. The shutdown mode reduces supply cur-
rent to 1µA (typ). Drive SHDN high for normal opera-
tion. Drive SHDN low to place the device in low-power
shutdown mode. In shutdown mode, the outputs are
high impedance; and the common-mode voltage at the
output decays to zero. In shutdown mode, connect
REGEN low to minimize current consumption.
The MAX9736 features a clickless-and-popless mute
mode. When the device is muted, the signal is attenuat-
ed at the speaker and the outputs stop switching. To
mute the MAX9736, drive MUTE low. Hold MUTE low
during system power-up and power-down to ensure
that clicks and pops caused by circuits before the
MAX9736 are suppressed.
Figure 1. MAX9736A Efficiency vs. Class AB Efficiency
100
90
80
70
60
50
40
30
20
10
0
0
vs. TOTAL OUTPUT POWER
TOTAL OUTPUT POWER (W)
5
MAX9736A
EFFICIENCY
CLASS AB
10
15
Mute Function
Efficiency
Shutdown
20
2
R loss of