Dear TI
UC3843A is used as flyback, the output voltage is non-isolation, input :11~120VDC
At light load ,increaing input voltage, the output PWM frequency is decreased, less than Oscillator frequency .
for example, the input voltage 60VDC, the PWM frequecy 40KHz ,Oscillator setting frequency is 160KHz, but the output voltage is stable
I want to know why caue this, is the operation mode normal ?