TPS62875-Q1: Datasheet formula question

xin

Part Number: TPS62875-Q1

hello sir,

When i calculate input capacitor of BUCK TPS6275-Q1, i find duty formula will divide efficiency. Why? From typical knowledge, BUCK duty=VOUT/VIN. Please help to check if it's right?

Cynthia

over 1 year ago

0 Excel Regidor over 1 year ago

TI__Mastermind 37141 points

Hello Cynthia,

Thanks for reaching out to us.

The duty formula below includes the efficiency because the converter also needs to deliver the dissipated energy as well. So, the calculation gives a more realistic duty cycle value instead not factoring the efficiency (D = Vout / Vin).

For Cin calculation, maximum value of the duty cycle is necessary to determine the highest possible input ripple current it needs to filter.

I hope I was able to address your queries.

Best regards,

Excel

0 Excel Regidor over 1 year ago in reply to Excel Regidor

TI__Mastermind 37141 points

Hello Cynthia,

Just a gentle reminder.

Do you still have further queries? If not, can you kindly close the thread?

Thank you.

Best regards,

Excel

0 xin over 1 year ago in reply to Excel Regidor

Intellectual 795 points

sorry for late to reply.

But not all TI power IC datasheet duty calculation is the same, some is considering efficiency, some are not. So, how to select?

+1 Excel Regidor over 1 year ago in reply to xin

TI__Mastermind 37141 points

Hi Cynthia,

If you want a more precise or needs the worst-case value of the duty cycle, use the equation with efficiency. Otherwise, the formula D = Vout / Vin should be enough.

Best regards,

Excel

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TPS62875-Q1: Datasheet formula question