What is the minimum controllable on-time for these parts? Datasheet doesn't specify it for any of these. LM20323 datasheet mentions that for on-time <= 200ns operation extra 22pF capacitor should be added to the feedback loop, I take that to mean that 200ns is on the low end for all of these devices.
The Cc2 capacitor adds extra pole on the feedback loop (as pointed out in LM20242 and LM20343) so it's not exactly "meant" for low on-time compensation.
I'd like to use 20242 part for 24->3.3V conversion, I take it I should keep it at 500kHz or less to stay on the good side of the Ton limits?
