TPS543C20: OCP in calculation ve. OCP in WEBENCH report

MINKYUNG KIM

Part Number: TPS543C20

Hi team,

I have question regarding to OCP setting of TPS543C20.

The operating condition is 12Vin, 0.9Vout, 17.8Aout, 491kHz, Lout = 0.47uH. I follow through the DS with Rlim = 30.1kOhm.

Iocp = (30.1kOhm * 11.2uA) / (16 * 0.58mOhm) - ((12V-0.9V)*0.9V) / (2 * 0.47uH * 491kHz * 12V) = 34.5238A

However, when I checked the design in WEBENCH, it shows me OCP level of 21.631A with the same 30.1kOhm on ILIM pin. I ran the simulation with TPS543C20A, which is an enhancement version with HS FET having the same operation on OCP circuitry. I attached the WEBENCH report. Could you clarify the correct OCP level?

WBDesign46 (2).pdf

Thanks,

over 4 years ago

0 Kris F over 4 years ago

TI__Genius 17905 points

Hi MINKYUNG KIM,

Your calculation looks correct. I will check with the WEBENCH team on how it is calculated in the tool and confirm if it needs to be corrected.

Regards,
Kris

0 MINKYUNG KIM over 4 years ago in reply to Kris F

Expert 1250 points

Thank you Kris,

Please kindly update me once you figure it out.

0 Kris F over 4 years ago in reply to MINKYUNG KIM

TI__Genius 17905 points

Sure, I will update here with the feedback from the WEBENCH team. Most likely some update is needed in the WEBENCH equations. I have already verified your your manual calculation is correct so you can proceed with your calculated value.

0 Kris F over 4 years ago in reply to Kris F

TI__Genius 17905 points

Hi,

WEBENCH team is fixing the equation used in the WEBENCH calculations for OCP to match the datasheet. It will be fixed by end of the month.

Regards,
Kris

0 Kris F over 4 years ago in reply to Kris F

TI__Genius 17905 points

The current limit calculations in WEBENCH have been updated.

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TPS543C20: OCP in calculation ve. OCP in WEBENCH report