ncp1234ad100r2g ON Semiconductor, ncp1234ad100r2g Datasheet - Page 17

• Manufacturer Part Number: ncp1234ad100r2g
• Description: Ncp1234 Fixed Frequency Current Mode Controller For Flyback Converters
• Manufacturer: ON Semiconductor

Oscillator with Maximum Duty Cycle and Frequency
Jittering
switching frequency with an accuracy of $7%. Two
frequency options can be ordered: 65 kHz and 100 kHz. The
maximum duty cycle of the DRV pin is 80%, with an
accuracy of $7%.
frequency jitters $6% around its nominal value, with a
triangle−wave shape and at a frequency of 125 Hz. This
frequency jittering is active even when the frequency is
decreased to improve the EMI in light load condition.
Nominal f
The NCP1234 includes an oscillator that sets the
In order to improve the EMI signature, the switching
f
f
OSC
OSC
OSC
+ 6
f
− 6
OSC
Figure 30. Frequency Jittering
(125 Hz)
8%
Time
http://onsemi.com
17
Clamped Driver
28 V, but most of the MOSFETs that will be connected to the
DRV pin cannot accept more than 20 V on their gate. The
driver pin is therefore clamped safely below 16 V. This
driver has a typical current capability of $500 mA.
The supply voltage for the NCP1234 can be as high as
DRV signal
Figure 31. Clamped Driver
Clamp
VCC
DRV