ncp1250 ON Semiconductor, ncp1250 Datasheet - Page 3

• Manufacturer Part Number: ncp1250
• Description: Ncp1250 Current-mode Pwm Controller For Off-line Power Supplies
• Manufacturer: ON Semiconductor

OPP
CS
FB
RFB
VDD
Vlatch
VDD
Vskip
/ 4.2
Vfold
gone?
OVP
Frequency
modulation
LEB
Frequency
foldback
Figure 2. Internal Circuit Architecture
RST
counter
Up
4
S
R
600 ns time
constant
Q
Q
250 mV
peak current
freeze
Rramp
Power on
reset
http://onsemi.com
The s oft −s tart is act ivated during:
− the s tartup sequence
− the auto−recovery burs t mode
VOPP
VDD
65/100 kHz
3
blanking
clock
on reset
1 ms
powe r
+
V FB < 1.05 V ? s e t p o in t = 250 mV
V
management
V
CC
limit
Vlimit + VOPP
an d log ic
hiccup
IpFlag
S
R
Q
Q
4 ms
SS
UVLO
IpFlag
Clamp
GND
VCC
Drv