LM5141-Q1: OCP issue : Vo return to error value

Eddie Chen1

Part Number: LM5141-Q1

12Vin to 3.3Vo design:

I use electronic load and set it be CC-mode to do OCP verify.

I add load slowly from 2A until hiccup OCP, and then to eliminate the load (return to no load) --> But Vo become to 5V??

How can I solve this issue?

Thanks.

over 3 years ago

0 Timothy Hegarty over 3 years ago

TI__Mastermind 49647 points

Hi Eddie,

Please send a completed LM5141-Q1 Excel quickstart file for this design (the file is available in the product folder).

I noted that the IAUC FET from Infineon has a 4.2V Miller plateau (see Fig 15 in the FET datasheet). This is very high relative to the 5V gate drive voltage and may result in adequate turn on. Please change to a lower threshold FET and retest (for example, use the same device as the high-side FET as this has quite low Rdson as well).

Also, you need some damping after the 3.5uH inductor. Use an electrolytic cap (Cdamp = 4 x Cin ceramic, derate the nameplate value for voltage) and a resistor in series = Rdamp = SQRT (Lin/Cin).

Regards,

Tim

0 Eddie Chen1 over 3 years ago in reply to Timothy Hegarty

Prodigy 150 points

Let's to discuss by mail.

0 Timothy Hegarty over 3 years ago in reply to Eddie Chen1

TI__Mastermind 49647 points

Thanks, Eddie.

I will close out this thread.

Regards,

Tim

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LM5141-Q1: OCP issue : Vo return to error value