Tool/software:
I used TI's online Designer for the ISOLATED FLYBACK configuration.
I wanted to use an off-the-shelf transformer with turns ratio of 1.2 : 2 : 1 (NP:NS:Naux) (10uH primary)
I used the Power Stage Designer tool to make mods and come up with what seemed to be a working configuration with this transformer.
I need 24V out at 1.5A. I have 24Vin with several amps available.
I came up with a seemingly working configuration and put it on a PCB.
It didn't work. There were several pulses driving the FET, the output rose up to 2V and then it stopped.
Then, it ramped down and repeated.
I increased soft-start time up to 100us, 500us, and 1ms; with no appreciable change in output.
I noticed that CURRENT SENSE was not connected even though a current resistor and filter were provided.
So, I tried the current filter to the CURRENT SENSE.
As before, there were several pulses driving the FET. The output rose to 5V, then stopped and rapped down.
I looked at the reference design for the PMP2215, and took some ideas from that to try.
I was never able to get above 12V.
Any suggestions?
