Gregory's Server
After some ngscopeclient updates and a busy week at work, back to playing with the LTC3374 test board.
Here's channel 1, with back side bulk cap and no high freq cap.. Input ripple ranges from 38 mV p-p / 1.4 mV RMS at no load to 57 mV p-p / 2.5 mV RMS at max design load of 1A.
Output ripple is *slightly* dependent on load, but much less of a shift. Pretty consistent around 21 mV P-P. / 5 mV RMS.
Now let's see what happens when we run the same filter graph on the other supplies.
Channel 2, bulk cap on back side plus high freq cap on the front. No changes to the output side.
Input ripple is greatly improved, ranging from 21 mV p-p / 0.86 mV RMS to 33 mV p-p / 1.7 mV RMS.
Output ripple is only slightly improved, hovering around 19 mV p-p / 4.65 mV RMS regardless of load.
So the high freq cap had a massive impact on input ripple, but fairly small improvement on the output side.