WEBENCH® Tools/LM5160-Q1: Switcher's source and ground pin is getting shorted.

ALOK GIRI

Part Number: LM5160-Q1

Tool/software: WEBENCH® Design Tools

Dear TI Team,

I have designed a Flybuck converter for 44Vin to 54Vin at 12Vout-iso, 1.2A using Webench. kindly find the design report in attachment, in order to get 12V output i have changed the values of rfbb and rfbt resistors , while operating at 44V initially the circuit works and shows the desired output voltage but after few cycles the switcher ic's pin (ie Vin and gnd) is getting shorted internally. kindly address me what possibly could be the reason. Final_48V-to-12V_Converter-7_Nos.pdf

over 5 years ago

0 Arief Hernadi over 5 years ago

TI__Mastermind 23835 points

Hi,

Do you use the same transformer part number that is recommended by webench?

Also, do you test this on our EVM?

Thanks

-Arief

0 ALOK GIRI over 5 years ago in reply to Arief Hernadi

Prodigy 60 points

Hello Arief,

yes, I have used the same transformer part number that is recommended by webench, the green waveform shown in the attached image is the voltage across the primary side of the transformer which have oscillations while switching,could it be the reason?.output is 15V instead of 12V because i still have to size the values feedback resistors.

I have not tested in your EVM, find my schematic circuit in the attachment

I have designed pcb layout accordingly.

Regards,

- Alok

0 Arief Hernadi over 5 years ago in reply to ALOK GIRI

TI__Mastermind 23835 points

Hi Alok,

The switching in the transformer should happen because the transformer will transfer the energy to the secondary of the circuit.

Is the part damaged after loading at the primary or secondary?

Can you try to load the primary output voltage and ensure you maintain regulation and stability?

Also, it's a good idea to double check against an EVM and we can send you one if you prefer

Thanks

-Arief

0 ALOK GIRI over 5 years ago in reply to Arief Hernadi

Prodigy 60 points

Dear Arief,

I have connected my load at secondary in order to get isolated output, kindly explain me how connecting load in primary will ensure stability? I would like to cross check with your EVM, can I a get a sample.

0 Arief Hernadi over 5 years ago in reply to ALOK GIRI

TI__Mastermind 23835 points

Hi Alok,

On a flybuck design, the regulation happens at primary. Therefore i want to ensure stability first by trying to see if the primary side of regulation is ok.

If you have an address, i can send an EVM to you

Thanks

-Arief

0 ALOK GIRI over 5 years ago in reply to Arief Hernadi

Prodigy 60 points

Hello Arief,

Do i need to pay for the EVM sample?

0 Arief Hernadi over 5 years ago in reply to ALOK GIRI

TI__Mastermind 23835 points

Hi Alok,

No, i can send you one if you are located within the USA.

Just let me know your shipping address

Thanks

-Arief

0 ALOK GIRI over 5 years ago in reply to Arief Hernadi

Prodigy 60 points

Dear Arief,

This is to bring you kind notice that i understood the flaw in my circuit and i successfully tested the design at rated condition.Thank you! for your support.

0 Arief Hernadi over 5 years ago in reply to ALOK GIRI

TI__Mastermind 23835 points

Hi Alok,

Sounds great. I am glad that you are able to resolve the issue

Thanks

-Arief

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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WEBENCH® Tools/LM5160-Q1: Switcher's source and ground pin is getting shorted.