NCP1654_09 ONSEMI [ON Semiconductor], NCP1654_09 Datasheet - Page 18

• Manufacturer Part Number: NCP1654_09
• Description: Power Factor Controller for Compact and Robust, Continuous Conduction Mode Pre-Converters
• Manufacturer: ONSEMI [ON Semiconductor]

Soft Start
function are as shown in Figure 42 and Figure 43. The
device provides no output (or no duty ratio) when the
V
when:
•
•
conditions;
Undervoltage Protection, the 200 mA current source block
keeps off. Hence only the Operating Trans−conductance
Amplifier (OTA) raises the V
slowly. This is to obtain a slow increasing duty cycle and
hence reduce the voltage and current stress on the
MOSFET. A soft−start operation is obtained.
control
The block diagram and timing diagram of soft start
When the IC recovers from one of the following
Brown−out, or
Undervoltage Protection
UVLO, BO, or UVP
is lower than V
Vout Low Detect
Undervoltage
Vdd Rising
Reset
Vdd
Vfb
Set
CONTROL(min)
Q
Lockout,
control
. V
. And V
Period I
control
Figure 43. Soft Start Timing Diagram
Brown−out
is pulled low
control
http://onsemi.com
rises
or
18
Vdd
Vfb
Period II
V
control
Figure 42. Soft Start Block Diagram
Bias
6
5
V
95%
REF
Off
V
REF
S
R
-
+
-
+
Q
Q
OTA
V
±20 mA
out
95% V
Low Detect
BO
REF
BO
UVLO
200 mA
UVLO
UVP
Vdd