SG1525A/SG1527A SERIES
APPLICATION INFORMATION
(continued)
SHUTDOWN OPTIONS
1. Use an external transistor or open-collector comparator to pull
down on the Comp terminal. This will set the PWM latch turning
off both outputs. If the shutdown signal is momentary, pulse-
by-pulse protection can be accomplished as the PWM latch will
be reset with each clock pulse.
2. The same results can be accomplished by pulling down on the
Soft-Start terminal with the difference that on this pin, shutdown
will not affect the amplifier compensation network but must
discharge any Soft-Start capacitor.
3. Apply a positive-going signal to the Shutdown terminal. This
will provide most rapid shutdown of the outputs but will not
immediately set the PWM latch if there is a Soft-Start capacitor.
This capacitor will discharge but with a current of approxi-
mately twice the charging current.
4. The shutdown terminal can be used to set the PWM latch on
a pulse-by-pulse basis if there is no external capacitance on
Soft-Start terminal. Slow turn-on may still be accomplished by
applying an external capacitor, blocking diode, and charging
resistor to the comp terminal. (See SG1524 Application Note).
SG1525A/1527A LAB TEST FIXTURE
11/91 Rev 1.3 10/96
Copyright
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1996
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