TPS2373-4EVM-758: Zener Diode

Mike Oudshoorn

Part Number: TPS2373-4EVM-758
Other Parts Discussed in Thread: UCC2897A

Tool/software:

Dear TI,

This is a follow up on the earlier post. something came inbetween so i was delayed with answering the details you asked for.

As you can see in the image below the duty cycle is very low. the output voltage of the converter is 1,3V which is not desired. If you need more information please let me know!

11 months ago

0 Diang Xing 11 months ago

TI__Mastermind 37111 points

Hi Mike,

Could you share your circuit schematic? What DC/DC controller you applied?

Best regards,

Diang

0 Mike Oudshoorn 11 months ago in reply to Diang Xing

Prodigy 30 points

Dear Diang,

See the attached File for the schematic. Im using the same circuit as used on the Eval board.

Kind regards,

Mike

7485.Hubbay-PoE PD.pdf

0 Diang Xing 11 months ago in reply to Mike Oudshoorn

TI__Mastermind 37111 points

Hi Mike,

Thanks for updates.

One thing I noticed is your VC_OUT cap is not 10x larger than the VC_IN cap. You can consider to make C80 = 1 - 10 uF. And try to measure the VC_IN - RTN and VC_OUT - RTN voltage. Let me know if it can fix or not.

Best regards,

Diang

0 Mike Oudshoorn 10 months ago in reply to Diang Xing

Prodigy 30 points

Dear Diang,

I replaced C80 with a 4,7uF cap. I measured Vcin and Vcout. they are switching. I also measured the supply voltage 54v. which is stable.

Green is VCIN, Blue is VCOUT and Yellow is VDD

Kind regards,

Mike

0 Diang Xing 10 months ago in reply to Mike Oudshoorn

TI__Mastermind 37111 points

Hi Mike,

Thanks for your updates. I will get back to you in 5 business days.

Best regards,

Diang

0 Diang Xing 10 months ago in reply to Diang Xing

TI__Mastermind 37111 points

Hi Mike,

Thanks for your patience.

It looks like the circuit goes into hiccup mode due to AC forward circuit overload.

Though the TPS2373-4's VC_IN and VC_OUT caps are corrected now, you may still need to open a new ticket to check with UCC2897A's engineer for the AC forward circuit issue.

Best regards,

Diang

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TPS2373-4EVM-758: Zener Diode