max9712eub Maxim Integrated Products, Inc., max9712eub Datasheet - Page 9

• Manufacturer Part Number: max9712eub
• Description: Max9712 500mw, Low Emi, Filterless, Class D Audio Amplifier
• Manufacturer: Maxim Integrated Products, Inc.

Figure 1. MAX9712 Outputs with an Input Signal Applied
spread over a bandwidth that increases with frequency.
Above a few MHz, the wideband spectrum looks like
white noise for EMI purposes (Figure 3).
The SYNC input allows the MAX9712 to be synchro-
nized to a system clock (allowing a fully synchronous
Table 1. Operating Modes
SYNC INPUT
Clocked
FLOAT
GND
V
DD
V
V
V
IN+
OUT+
IN-
- V
OUT-
FFM with f
FFM with f
SSM with f
FFM with f
OUT+
OUT-
_______________________________________________________________________________________
t
ON(MIN)
S
S
S
S
= 1100kHz
= 1450kHz
= external clock frequency
= 1220kHz 120kHz
MODE
External Clock Mode
t
SW
500mW, Low EMI, Filterless,
Class D Audio Amplifier
system), or allocating the spectral components of the
switching harmonics to insensitive frequency bands.
Applying an external TTL clock of 800kHz to 2MHz to
SYNC synchronizes the switching frequency of the
MAX9712. The period of the SYNC clock can be ran-
domized, enabling the MAX9712 to be synchronized to
another MAX9712 operating in SSM mode.
The MAX9712 uses Maxim’s unique, patented modula-
tion scheme that eliminates the LC filter required by
traditional class D amplifiers, improving efficiency,
reducing component count, conserving board space
and system cost. Conventional class D amplifiers out-
put a 50% duty cycle square wave when no signal is
present. With no filter, the square wave appears across
Filterless Modulation/Common-Mode Idle
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