NCP1237 ONSEMI [ON Semiconductor], NCP1237 Datasheet - Page 3

• Manufacturer Part Number: NCP1237
• Description: Fixed Frequency Current Mode Controller for Flyback Converters
• Manufacturer: ONSEMI [ON Semiconductor]

Latch
CS
FB
I
NTC
HV sample
V
VDD
S
DD
R
R
S
R
Q
Q
1 kW
V
Vclamp
FB(up)
I
(V
FB(OPC)
OPC
V to I
HV
PWM
−125)
= 0.5m x
Fault Flag
I
TRAN
−
+
blanking
I
blanking
NTC
t
t
LEB
BCS
ILIMIT
DMAX
+
FB
+
V
K
OTP
+
−
FB
V
+
t
CS(tran)
t
fault
tran
SIMPLIFIED INTERNAL BLOCK SCHEMATIC
+
V
Figure 3. Simplified Internal Block Schematic
+
timer
−
Soft−start
ramp
End
+
−
OVP
V
Brown−out
Soft−start end
CS(stop)
t
+
+
−
+
Soft−start
end
SSTART
−
Soft−start
Fault
Reset
comp.
slope
+
t
Reset
−
t
Latch(OVP)
Start
Latch(OTP)
blanking
UVLO
blanking
+
PWM
+
Brown−out
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Vskip
IC Start
IC Stop
V
Reset
ILIM
I
+
−
TRAN
+
−
S
R
3
Q
Protection
release
Brown−out
Mode
Skip
I
HV stop
LIMIT
Latch
IC Start
Reset
UVLO
IC stop
VDD
timer
t
autorec
HV sample
TSD
Soft−skip ramp
Reset
Autorecovery
mode only
protection
t
SSKIP
Skip
D
MAX
Reset
UVLO
VDD
Start
TSD
Stop
Sawtooth
management
Oscillator
HV current
TSD
D
BO
OVM
HV dc
Foldback
V
CMAX
CC
HV stop
Jitter
−
S
R
+
Dual HV
start−up
current source
Q
FB
Latch
TSD
Clamp
HV
VCC
DRV
GND