Email from customer:
I am experiencing a problem with one of your components and I was hoping you could assist me with the issue.
I need a Current-Mode PWM Controller with a low start up threshold for a COTS flyback converter. I originally was using the UCC3803. However, this controller caused me a problem when running very small duty cycles because of its built in leading edge blanking time. So I then switched to the UCC38C40. This controller worked for my minimum duty cycle conditions but I see a half switching frequency oscillation in the PWM output of the UCC38C40. I troubleshoot my circuit to determine were the oscillation was being introduce to no avail. Without changing any other components in my circuit, I replaced the UCC38C40 with a UCC3843B and the oscillation was no longer present. It appears that the UCC38C40 has a sensitivity that causes a half switching frequency oscillation in its output.
Can you please help me determine a solution to this oscillation? Or could you recommend a difference Current Mode PWM controller with a low start threshold and no leading edge blanking built in?
