I'm working on a buck regulator to bring 16-30VDC down to 14V. It seems to be working nicely but I'm seeing jitter on the PWM.
It looks a bit like frequency dithering to mitigate EMI issues , but I see nothing mentioned about that in the datasheet.
It looks exactly the same even if I sweep the input voltage from 15V to 30V and change the load from 2A down to 400mA. Below that it goes to PFM mode , so that's fine.
The duty cycle and amplitudes change as expected , but the jitter is always there.
Regulation is good and efficiency is close to 96% , so I was wondering if this is intended or is there a stability issue. I've tried adding capacitance (multiple 10uF ceramic 50V) to the input and
output and it makes absolutely no difference to the waveform. Also changed the inductor from 10uh , 15uH and 33uH. Again no difference at all to the PWM jitter , which is making me think it's not a stability issue, but I may be wrong.
Cheers
Rob