Flying Capacitor Selection

[gkkrish52]

Hi. I am working on 1/2 step down switched capacitor dc dc converter. The relation between ripple and load is given by the equation delta_V = t x I / C. My load is 10 mA and Ripple i want is 50 mV. How much should be C and t ? I want to fix C and find the time required for charging it.

Thanks in advance for your help. Have a nice day.

Best,
Gopal

 

[barry]

You're asking us to do simple algebra for you? No thanks.

 

[gkkrish52]

Dear Barry,

I am unable to fix the time taken to charge the capacitor. It is not about simple algebra though.

Best,
Gopal

 

[KlausST]

Hi,

If you don't know the timing, how do you think we can know?
We are not able to mind read, we are not able to see your schematic, we can not connect a scope or a frequency meter to your circuit ... we only have the informations you give us.

Klaus

 

[barry]

Dear Barry,

I am unable to fix the time taken to charge the capacitor. It is not about simple algebra though.

Best,
Gopal

It is absolutely about algebra. You have two variables, fix one and you can calculate the other. You could use a capacitor with infinite capactance, and your charging time will be zero; you could use a capacitor with zero capacitance and your charging time will be infinite. Or you can pick some rational values in between.

- - - Updated - - -

I messed up. Infinite capacitance==> infinite time.