AAT1415 Datasheet, PDF (25/32 Pages) Advanced Analog Technology, Inc. – FIVE-CHANNEL DC-DC CONVERTER WITH A 2.5V LDO

Soft Start Waveform
Advanced Analog Technology, Inc.
May 2008
AAT1415/AAT1415A
Figure 7. Timing Chart of Soft-Start
Figure 8. Oscillator Frequency
Low-Voltage Startup Oscillator
The AAT1415/AAT1415A internal control and
reference voltage circuitry receives power from VDD
and do not function when VDD is less than 2.5V. To
ensure low voltage startup, the CH1 employs a
low-voltage startup oscillator (about 200kHz) that
activates at 1.2V if a Schottky diode is connected from
PWR to OUT1. The startup oscillator drives the internal
NMOS at SW1 until VDD reaches 2.5V, at which point
voltage control is passed to the normal oscillator
(current-mode PWM circuitry). At low input voltages,
the CH1 can have difficulty starting into heavy loads.
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Version 3.00
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