# MP9486 Capacitor Values 72V(Vin) - 16V(Vout), Iout 1A

I’m trying to design a 72v input to 16v output with 1A and 20% ripple current with MP9486. I need help in calculating the Capacitor Values.

Good luck with that, going to be difficult/impossible or you are smarter than me. This is a voltage mode part and operates in a hysteretic way so no clock even. Why do you suppose you need 20% ripple current?

hi J Shannon i am a fresher and this hysteresis voltage mode control is really new to me and i cant find any reference designs using this module. not even available in MPS’s dc-dc designer. this was a task given to me from a startup. I used the ev9486 evaluation board’s datasheet where if i just change the resistor values I could get the desired output. but is it efficient? I saw that 20%-40% as an typical ripple current. have u built these type of systems? what other details is needed?
Thanks

I don’t have a lot of experience with these. Looking at the datasheet, what turns the switch on and starts adding power to the output is Vfb of 185mV or less. There are two things that turn the switch Off a peak current of 1A or a Vfb of 215mV.

Except, the datasheet is confusing in this regard as VFBH and VFBL are specified, as stated but if you look at the block diagram it looks like those numbers are “adaptive” and processed in some circuit block in some mysterious way.

Looks like they want you to use an output cap with some ESR to inject some extra hysteresis signal into the vfb.

I expect it is decently efficient if the frequency isn’t crazy. A bit tweaky is all.
Good luck

I need to learn and work on it if I’m going to build the system completely.
Meanwhile can I Just use this Evaluation Board’s Schematic just by changing the Resistors Values To 790K Ohms for R1. And C2A and C2B for 25V 20% ripple Variants.