Datasheet

NCP1216, NCP1216A
http://onsemi.com
15
Figure 27. Figure 28.
A simple resistor in series avoids any latchup in the controller
or one diode forces V
CC
to reach V
CCON
sooner.
D3
1N4007
1
2
45
8
6
7
3
+
+
CV
CC
C
bulk
1
2
45
8
6
7
3
+
+
CV
CC
C
bulk
R
bulk
> 4.7 k
Soft−Start − NCP1216A only
The NCP1216A features an internal 1.0 ms soft−start
activated during the power on sequence (PON). As soon as
V
CC
reaches V
CCOFF
, the peak current is gradually
increased from nearly zero up to the maximum clamping
level (e.g. 1.0 V). This situation lasts during 1ms 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 29 portrays the soft−start behavior. The time scales
are purposely shifted to offer a better zoom portion.
Figure 29. Soft−start is activated during a startup sequence or an OCP condition