Advanced Analog Technology, Inc.
April 2007
AAT1164/AAT1164B/AAT1164C
Soft Start Waveform
supply. The ground connection of the VDD and VREF
bypass capacitor should be connected to the analog
ground pin (GND) with a wide trace.
LAYOUT CONSIDERATION
The system’s performances including switching noise,
transient response, and PWM feedback loop stability
are greatly affected by the PC board layout and
grounding. There are some general guidelines for
layout:
Output Capacitors
Place output capacitors as close as possible to the IC.
Minimize the length and maximize the width of traces to
get the best transient response and reduce the ripple
noise. We choose 10µF ceramics capacitor to reduce
the ripple voltage, and use 0.1µF ceramics capacitor to
reduce the ripple noise.
Inductor
Always try to use a low EMI inductor with a ferrite core.
Filter Capacitors
Place low ESR ceramics filter capacitors (between
0.1µF and 0.22µF) close to VDD and VREF pins. This
will eliminate as much trace inductance effects as
possible and give the internal IC rail a cleaner voltage
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Advanced Analog Technology, Inc. –
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