TPS54425 max duty cycle

toapex

Prodigy 230 points

Other Parts Discussed in Thread: TPS54425

is it possible to change 5.5v to 5v by using TPS54425?

what's the maximum duty cycle when Vin=5.5v?

any equations or relationship to show the max duty cycle between Vin and Vout.

thank you!

over 8 years ago

0 JohnTucker over 8 years ago

TI__Guru**** 191445 points

Duty cycle is limited by the minimum off time. Vout max = Vin min * ( 1 - Fsw * 310E-9). That is the hard limit. Regulation degrades slightly as the input voltage approaches the minimum.

0 toapex over 8 years ago in reply to JohnTucker

Prodigy 230 points

but its Fsw is changing with Vin&Vout because of the adaptive on-time scheme, in figure 9 , page 11th of the IC's datasheet, i could read Fsw=560KHz approximately when Vin=5v and Vo=3.3v, so what's the Fsw when Vo=5v and Vin=5.5v? is is possible or the Fsw in the equation you give is a designated 700KHz?

0 JohnTucker over 8 years ago in reply to toapex

TI__Guru**** 191445 points

You just have to estimate it based on the datasheet curve.

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TPS54425 max duty cycle