max98306 Maxim Integrated Products, Inc., max98306 Datasheet - Page 9

• Manufacturer Part Number: max98306
• Description: Stereo 3.7w Class D Amplifier
• Manufacturer: Maxim Integrated Products, Inc.

The MAX98306 features low quiescent current, a low-
power shutdown mode, comprehensive click-and-pop
suppression, and excellent RF immunity.
The IC offers Class AB audio performance with Class D
efficiency in a minimal board-space solution.
The Class D amplifier features spread-spectrum modula-
tion, active emissions limiting, edge-rate, and overshoot
control circuitry that offers significant improvements to
switch-mode amplifier radiated emissions.
The amplifier also features click-and-pop suppression
that reduces audible transients on startup and shut-
down, as well as thermal-overload and short-circuit
protection.
The filterless Class D amplifier output stage offers much
higher efficiency than Class AB amplifiers. The high effi-
ciency of a Class D amplifier is due to the pulse-width
modulated (PWM) rail-to-rail switching operation of the
output stage transistors. This ensures that any power
loss associated with the Class D output stage is mostly
due to the I
quiescent current overhead.
Traditional Class D amplifiers require the use of external
LC filters, or shielding, to meet EN55022B electromag-
netic-interference (EMI) regulation standards. Maxim’s
active-emissions-limiting edge-rate control circuitry and
spread-spectrum modulation reduce EMI emissions,
while maintaining up to 92% efficiency.
Spread-spectrum modulation and active emissions limit-
ing limit wideband spectral components, while propri-
etary techniques ensure that the cycle-to-cycle varia-
tion of the switching period does not degrade audio
reproduction or efficiency. The IC’s spread-spectrum
modulator randomly varies the switching frequency by
Q20kHz around the center frequency (320kHz). Above
10MHz, the wideband spectrum looks like noise for EMI
purposes (Figure 1).
If the output current of the speaker amplifier exceeds
the current limit (3A typ), the IC disables the outputs for
approximately 100Fs. At the end of 100Fs, the outputs
are reenabled. If the fault condition still exists, the IC
continues to disable and reenable the outputs until the
fault condition is removed.
2
R loss of the MOSFET on-resistance and
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Detailed Description
Class D Speaker Amplifier
EMI Filterless Output Stage
Speaker Current Limit
Stereo 3.7W Class D Amplifier
Table 1. Gain Control Configuration
Figure 1. EMI with 12in of Speaker Cable and No Output Filter
The IC offers five programmable gains selected using
the GAIN input.
The IC features a low-power shutdown mode, drawing
P 1FA (typ) of supply current. Drive SHDN low to place
the MAX98306 into shutdown. Drive SHDN above 1.4V
for normal operation.
The IC speaker amplifier features Maxim’s comprehen-
sive click-and-pop suppression. During startup, the
click-and-pop suppression circuitry reduces any audible
transient sources internal to the device. When entering
shutdown, the differential speaker outputs ramp down to
PGND quickly and simultaneously.
Connect to PGND
Connect to PGND through
100kI ±5% resistor
Connect to PVDD
Connect to PVDD through
100kI ±5% resistor
Unconnected
GAIN PIN
-10
90
80
70
60
50
40
30
20
10
0
0
100
200 300 400 500
Click-and-Pop Suppression
FREQUENCY (MHz)
MAXIMUM GAIN (dB)
600 700
Selectable Gain
800
18
15
12
900
9
6
Shutdown
1000
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