NCP1234 ONSEMI [ON Semiconductor], NCP1234 Datasheet - Page 3

• Manufacturer Part Number: NCP1234
• Description: Fixed Frequency Current Mode Controller for Flyback Converters
• Manufacturer: ONSEMI [ON Semiconductor]

Latch
CS
FB
I
HV sample
NTC
V
FB(ref)
V
S
R
DD
Q
1 kW
20 kW
V
clamp
I
OPC
PWM
V
(V
I
FB(OPC)
LIMIT
HV
Fault Flag
V to I
= 0.5m x
−
− 125)
+
I
NTC
blanking
blanking
t
t
LEB
BCS
+
+
V
OTP
/ 5
+
−
+
t
fault
SIMPLIFIED INTERNAL BLOCK SCHEMATIC
+
V
Figure 2. Simplified Internal Block Schematic
+
timer
OVP
−
Soft−start ramp Start
+
End
−
V
CS(stop)
Soft−start end
+
−
+
Soft−start
end
−
Soft−start
t
Fault
SSTART
t
Latch(OVP)
blanking
comp.
t
slope
Latch(OTP)
blanking
Reset
+
PWM
Reset
+
http://onsemi.com
V
skip
V
Reset
+
ILIM
−
IC Start
IC Stop
+
−
S
R
3
Q
Protection
release
Mode
I
LIMIT
Latch
IC Start
UVLO
timer
IC stop
VDD
t
autorec
TSD
For
Autorecovery
protection
mode only
Reset
UVLO
V
Start
TSD
DD
Sawtooth
Stop
HV current
Oscillator
management
TSD
Foldback
V
Jitter
CC
HV
S
R
Dual HV
start−up
current source
Q
Latch
TSD
UVLO
Clamp
V
DRV
GND
HV
CC