max9700beub Maxim Integrated Products, Inc., max9700beub Datasheet - Page 9

• Manufacturer Part Number: max9700beub
• Description: 1.2w, Low-emi, Filterless, Class D Audio Amplifier
• Manufacturer: Maxim Integrated Products, Inc.

Figure 1. MAX9700 Outputs with an Input Signal Applied
spread over a bandwidth that increases with frequency.
Above a few megahertz, the wideband spectrum looks
like white noise for EMI purposes (Figure 3).
The SYNC input allows the MAX9700 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
1.2W, 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
MAX9700. The period of the SYNC clock can be ran-
domized, enabling the MAX9700 to be synchronized to
another MAX9700 operating in SSM mode.
The MAX9700 uses Maxim’s unique, patented modula-
tion scheme that eliminates the LC filter required by
traditional 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
Filterless Modulation/Common-Mode Idle
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