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?
BR
Cynthia
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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?
BR
Cynthia
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
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
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?
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