MAX9759 Maxim Integrated Products, MAX9759 Datasheet - Page 12

• Manufacturer Part Number: MAX9759
• Description: 3.2W High-Efficiency Low-EMI Filterless Class D Audio Amplifier
• Manufacturer: Maxim Integrated Products

3.2W, High-Efficiency, Low-EMI, Filterless,
Class D Audio Amplifier
Figure 2. MAX9759 Outputs with an Input Signal Applied (SSM Mode)
The SYNC function allows the MAX9759 to allocate
spectral components of the switching harmonics to
insensitive frequency bands and facilitates synchroniza-
tion to a system clock (allowing for a fully synchronous
system). Applying an external TTL clock of 1000kHz to
1600kHz to SYNC synchronizes the switching frequency
of the MAX9759. The period of the SYNC clock can be
randomized, enabling the MAX9759 to be synchronized
to another MAX9759 operating in SSM mode.
The SYNC_OUT function of the MAX9759 allows for
multiple Maxim class D amplifiers to be cascaded and
frequency locked. Synchronizing multiple class D
amplifiers ensures that no beat frequencies within the
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V
V
V
OUT+
IN+
IN-
- V
OUT-
OUT+
OUT-
t
ON(MIN)
External Synchronization
Cascading Amplifiers
t
SW
t
SW
audio spectrum occur on the power-supply rails. Any
intermodulation distortion due to the interference of
several modulation frequencies is minimized as a
result. Leave the SYNC_OUT pin of the MAX9759 float-
ing if the SYNC_OUT function is not applicable.
The MAX9759 uses Maxim’s unique, patented modula-
tion scheme that eliminates the LC filter required by tra-
ditional class D amplifiers, improving efficiency,
reducing component count, and conserving board
space and system cost. Conventional class D amplifiers
output a 50% duty-cycle square wave when no signal is
present. With no filter, the square wave appears across
the load as a DC voltage, resulting in finite load current,
increasing power consumption. When no signal is pre-
Filterless Modulation/Common-Mode Idle
t
SW
t
SW
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