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fast CC/CV power supply... again

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exe:

--- Quote from: ArdWar on July 01, 2024, 06:07:31 pm --- Are you sure your gate are actually at zero during the "taper off" period?

--- End quote ---

Yes, I measured it. There is a 2us delay between the time the gate is off and mosfet stops conducting.

exe:
I compared three different bjts for current limiting. To my surpise, the winner is 2n3904 (can't identify company, probably onsemi, beta 300). It has the smallest overshoot. Next bc849c bc549c (fairchild, beta 600), then d882 (ST, beta 200). For those who play along at home, vertical scale is 200mA/division. That's because it measures voltage across 0R25 resistor.

I expected bc849c to win because I thought it has smaller die due to lover current rating. However, in the datasheets, it has nearly identical capacitances with 2n3904.

Peak current is 240mA, recovery takes only 130ns, I think it's a success).

NB I changed scope parameters such as bandwidth (now its 20MHz lowpass, 10X probe), switched back to AP2312 mosfet, and limited voltage to 20V. Because of that, results are not directly comparable with previous screenshots.

exe:
JFYI I was revisiting this approach recently while designing yet another power supply and I found this approach... impractical. Too much drop is required for this to work. I though I might compensate for that with a faster circuitry, but, alas, not really. Together with output capacitor this creates too much of phase shift to my liking.

So, not continuing this way.

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