ncp1216a ON Semiconductor, ncp1216a Datasheet - Page 15

• Manufacturer Part Number: ncp1216a
• Description: Pwm Current-mode Controller For High-power Universal Off-line Supplies
• Manufacturer: ON Semiconductor

Soft−Start − NCP1216A only
activated during the power on sequence (PON). As soon as
V
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
CC
The NCP1216A features an internal 1.0 ms soft−start
reaches V
+
C
bulk
CCOFF
Figure 29. Soft−start is activated during a startup sequence or an OCP condition
Figure 27.
1
2
3
4
, the peak current is gradually
8
7
6
5
A simple resistor in series avoids any latchup in the controller
or one diode forces V
+
R
> 4.7 k
CV
NCP1216, NCP1216A
bulk
CC
http://onsemi.com
CC
15
to reach V
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
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.
CC
ramps up either from zero (fresh power−on sequence)
CCON
sooner.
+
C
bulk
1
2
3
4
Figure 28.
8
7
6
5
+
CV
D3
1N4007
CC