NCP1217, NCP1217A
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16
Soft−Start (NCP1217A only)
The NCP1217A features an internal 1.0 ms soft−start
activated during the power on sequence (PON). As soon as
V
CC
reaches VCC
OFF
, the peak current is gradually
increased from nearly zero up to the maximum clamping
level (e.g. 1.0 V). This situation lasts during 1.0 ms and
further to that time period, the peak current limit is blocked
to 1.0 V until the supply enters regulation. The soft−start is
also activated during the Over Current Burst (OCP)
sequence. Every restart attempt is followed by a soft−start
activation. Generally speaking, the soft−start will be
activated when V
CC
ramps up either from zero (fresh
power−on sequence) or 5.6 V, the latchoff voltage occurring
during OCP. Figure 30 portrays the soft−start behavior. The
time scales are purposely shifted to offer a better zoom
portion.
Figure 30. Soft−start is activated during a startup sequence or an OCP condition
