The buck converter input ripple current formula derivation

Hi Nick,

Are you looking for any particular device or a general one?

Regards,

Febin

I just want a general buck converter.

the formula is Iin.ripple = Io*√[D*(1-D)]

Thanks.

Hi Nick,

Following two app notes can help you to calculate the output ripple of buck converter. it mostly depend on many factors like device capacitators, inductor and duty cycle selection. If you looking for particular device buck converter ripple requirements than I would suggest to use Webench model. It can help you to give data for all operating conditions.

https://www.ti.com/lit/an/slyt293/slyt293.pdf?ts=1640593542547

https://www.ti.com/lit/an/slva057/slva057.pdf?ts=1640593552829

Hope this can help!

Best regards,

Tanvee

Hi Tanvee,

I want the input ripple current(Icin) to show as below red part.

Thanks.

Hi Nick,

I misunderstood the question.

The formula you have mentioned will give you the expected input ripple current RMS. This formula is well explain in this app note.   https://www.ti.com/lit/an/slyt670/slyt670.pdf?ts=1640595281717&ref_url=https%253A%252F%252Fwww.google.com%252F

Best regards,

Tanvee

Could you give me the detail, about the input ripple current formula derivation ?

Hi Nick,

There is no specific deviation formula.. it mostly depends on your supply , input capacitor selection.

 What is major concern here for your application?

Best regards,

Tanvee

Hi Tanvee,

I don't have any concern.

I am pure to want the input ripple current derivation by general buck.

because I search any website can not find about it. 

Thanks.

Hi Nick,

I mentioned before there is no specific formula for calculation. It depends on your supply external components tolerance.

Best regards,

Tanvee