cupoftea
Advanced Member level 6
When you are testing a 400kHz 20vin 60W, 30Vout DCDC Boost SMPS for stability, you obviously look at Vout
over multiple time bases.....say 2us/div to 50ms/div....why not look over that range?...all you have to
do is turn the timebase dial...might as well view it over that full range.
You would also look at the error amplifier output if it was available...on max load....and again over
the same timebase range as above.
As well as that, I would also look at the fet drain voltage pulses....from a timebase of some 2us/div....right up to that
maximum timebase that still allows you to see the drain voltage pulses.....whatever timebase that is....obviously on 1s/div
you wont be able to see the pulse to pulse spacing any more....but might as well look over the widest timebase possible.
However, our contractor, when looking at the drain voltage pulses, he just gets three switching periods on the scope, and if the distance
between the drain pulses is the same, and they are the same width, then he declares stability, and wont bother looking over any wider
timebase Setting. We think this is skimping it.
What say thee about this?
over multiple time bases.....say 2us/div to 50ms/div....why not look over that range?...all you have to
do is turn the timebase dial...might as well view it over that full range.
You would also look at the error amplifier output if it was available...on max load....and again over
the same timebase range as above.
As well as that, I would also look at the fet drain voltage pulses....from a timebase of some 2us/div....right up to that
maximum timebase that still allows you to see the drain voltage pulses.....whatever timebase that is....obviously on 1s/div
you wont be able to see the pulse to pulse spacing any more....but might as well look over the widest timebase possible.
However, our contractor, when looking at the drain voltage pulses, he just gets three switching periods on the scope, and if the distance
between the drain pulses is the same, and they are the same width, then he declares stability, and wont bother looking over any wider
timebase Setting. We think this is skimping it.
What say thee about this?