Can HFC0100 handle 75W output ; [12V ,2.2A+140V,0.35A] ; if yes, how can I control the frequency to operate at 100khz at full load? when I set the current limiter at 270mohm for 3.6Peak current ;instead of operating at 100khz as expected, the IC starts valley skipping mode resulting in decreased frequency(65k).
It is a controller so can have any output power you want. The frequency of operation is variable with line and load. So for some combination of load, turns ratio, and input voltage it will operate at 100.00 khz. Mostly it won’t though.
Thank you for your reply; why does the IC start skipping valleys although the frequency is below the maximum limit ? The combination of load, turns ratio, and input voltage is supposed to operate the system at 100khz, if the switched is turned on with the first valley.
I think the system hits the minimum turn off limit causing the operating frequency to reduce to 65khz. is there anyway to overcome this limitation noting that the operating frequency is much smaller than IC maximum frequency(150khz)
Fig 4 of the datasheet shows the minimum off time of 7.8usec. It shows the first valley being skipped as it occurs too soon after the main switch turned off. Maybe?
So the switch retriggers on the first valley after 7.8usec has passed. I can’t determine what your off time is from the scope traces.
Yes, it is indeed 7.8usec;
I have to reduce the inductance or operate at lower frequency.
thanks.