Hi,
I am developing two circuits - a H-bridge inverter and a boost converter, both of which use a MOSFET(s) with a PWM drive and resistive load. I observe:
a. The rise time measured across the drain and source *reduces* as the output load (as in more amps taken at a given output voltage) on these circuits *increases*.
b. On the boost converter, for very light loads, the drain to source waveform does not remain completely rectangular. The rising/leading edge of the switching waveform is correct, but the later part (just before the falling/lagging edge) turns "wavy".
I would like to know if the two behaviours described above are expected. Anybody else can confirm/deny that they have observed something like this? Any explanation of what could be happening is welcome.
Regards, Anand