NCP1234 ONSEMI [ON Semiconductor], NCP1234 Datasheet - Page 22

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

Feedback with Slope Compensation
is 5, meaning that the FB voltage corresponding to V
duty cycle above 50%, a fixed slope compensation is
internally applied to the current−mode control. The slope
The ratio from the FB voltage to the current sense setpoint
In order to allow the NCP1234 to operate in CCM with a
detector
V
HV(stop)
Peak
I
V
OPC
HV
Figure 38. Overpower Compensation if the HV Pin is Connected to DC Voltage
t
wd
Sample
CS
FB
Figure 39. FB Circuitry
20 kW
http://onsemi.com
ILIM
t
blanking
wd
Sample
t
LEB
V
is
FB(ref)
K FB
22
3.5 V. There is a pull−up resistor of 20 kW from FB pin to an
internal reference.
appearing on the internal voltage setpoint for the PWM
comparator is −32.5 mV/ms typical for the 65 kHz version,
and −50 mV/ms for the 100 kHz version.
+
−
t
wd
Sample
PWM
Reset
t
HV
Reset
time
time
time