TPS63802: The calculation of D

Skylar Li

Part Number: TPS63802

Hi Experts,

Today I read an AN called Basic Calculations of a 4 Switch Buck-Boost Power Stage as attached and found the formula as below.

slva535b.pdf

May I ask why the D is related to the efficiency?

Also here is the calculation process as below.

By referring the formula, I could not get the 0.614 and 0.330 results. Could you pls help it? Thanks!

BR,

Skylar

6 months ago

0 Tao Zhang 6 months ago

TI__Mastermind 24605 points

Hi Skylar,

A miistake in this PDF that the Vin_max in Boost duty cycle calculation should be Vin_min. Then you can get same results as PDF's.

Good question about duty calculation. There is a gap between ideal duty cycle and actual one, if voltage drop on FET is considered, then you will get a true duty cycle, and it is close to the calculation in PDF.

Regards

Tao

0 Skylar Li 6 months ago in reply to Tao Zhang

TI__Intellectual 1210 points

Hi Tao，

Also in the Dbuck，we could get 0.614 by multipling the efficiency rather than dividing the efficiency.

Could you pls confirm it？Thanks！

B R，

Skylar

0 Tao Zhang 6 months ago in reply to Skylar Li

TI__Mastermind 24605 points

Hi Skylar,

Multipling the EFF is correct because this calculation is more close to actual D.

Regards

Tao

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TPS63802: The calculation of D