TPS628501-Q1: Power management forum

xin

Intellectual 575 points

Part Number: TPS628501-Q1

Hi sir,

TPS628501-Q1: I can't find inductor calculation formula in the datasheet , could you give the formula?

Thanks

Cynthia

over 1 year ago

0 Stefano Panaro over 1 year ago

TI__Expert 7585 points

Hi Cynthia,

Thanks for contacting us.

The answer is similar to the previous one ((+) TPS62812-Q1: Power management forum - Power management forum - Power management - TI E2E support forums).

In this case, the recommended range is:

In particular this device has been optimized for a nominal 0.47-µH inductor with a switching frequency of typically 2.25 MHz.

Please refer to the datasheet for further details.

Thanks,

Stefano

0 xin over 1 year ago in reply to Stefano Panaro

Intellectual 575 points

thanks for your reply.

so, you mean the inductor value can't exceed this range, right? Because i calculate the value referring to similar buck of TI.

For our application, frequency is 2.233MHz by connected 8.06K resistor in pin4.

Vin=5V, Vout=1.8V, Iout=0.1A, the inductor value is almost 17uH. Is not correct?

+1 Stefano Panaro over 1 year ago in reply to xin

TI__Expert 7585 points

Hi Cynthia,

The formula is in theory correct, but it won't work for our converter. Since the compensation network is integrated, you need to pick an inductance value inside the recommended range. If you use a 17uH inductor, you would very likely have stability / load transient problems.

I would recommend to use either 470nH (optimal) or 1uH inductor at 2.25MHz.

For a 0.1A, I would expect the device to either run in DCM (PFM mode), or to run in CCM with a negative minimum inductor current.

If you are interested in the details, you can simulate the behavior with the device models.

Thanks,

Stefano

0 xin over 1 year ago in reply to Stefano Panaro

Intellectual 575 points

understand, thanks very much