Datasheet

TPS2480
TPS2481
www.ti.com SLUS939B –APRIL 2010–REVISED DECEMBER 2010
TIMER and PG Operation (Figure 12)
The TIMER pin charges C
T
as long as limiting action continues, and discharges at a 1/10 charge rate when
limiting stops. If the voltage on C
T
reaches 4 V before the output is charged, the external FET is turned off and
either a latch-off or restart cycle commences, depending on the part type. The open-drain PG output provides a
deglitched end-of-charge indication which is based on the voltage across the external FET. PG is useful for
preventing a downstream DC-to-DC converter from starting while C
O
is still charging. PG goes active (open
drain) about 9 ms after C
O
is charged. This delay allows the external FET to fully turn on and any transients in
the power circuits to end before the converter starts up. The resistor pull-up shown on pin PG in the typical
application diagram only demonstrates operation; the actual connection to the converter depends on the
application. Timing can appear to terminate early in some designs if operation transitions out of the power limit
mode into a gate charge limited mode at low V
DS
values.
Figure 12. Basic Board Insertion
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