LM25185-Q1: Using LM25185-Q1 as a controller for converting 400V/800V to 12V

Masaru Oinaga

Part Number: LM25185-Q1
Other Parts Discussed in Thread: LM5156

Hello, Team,

Our customer is currently trying to implement a converter which down converts 400Vdc or 800Vdc to 12Vdc. They are interested in UCC28C5x-Q1 and LM25185-Q1. We are aware that LM25185-Q1 can only support up to 100V, but can it also be used for 400V/800V system if its input is bucked by an external circuit such as Zener diodes or transistors?

Please let us know what kind of issues/challenges will this approach have if it is possible. If not, please suggest us with other devices.

Requirements are:

Automotive
Input Voltage: 150V ~ 900V
Output Voltage: 12V
Output Power: 300W
Junction Temperature: 150 degC
Ambient Temperature: -40 degC ~ -125degC
Other: Would be great if the power IC is capable of inputting directly from input voltage (150V~900V)

Best Regards,
Masaru Oinaga

5 months ago

+1 Youhao Xi 5 months ago

TI__Guru 72845 points

Hi Masaru,

Thank you very much for reaching out and for considering LM25185-Q1. Unfortunately the device cannot support an input voltage higher than its VIN max rating. It is because VIN pin needs to be tied directly to the input line to monitor the output voltage via transformer winding. We are still investigating a workaround but currently no proven method has been identified. I will contact you once we figure out a way. You may consider the LM5156 but 300W is also a concern for a flyback. I would suggest a forward or half-bridge topology supported by HVP groups.

Thanks,

Youhao

0 Masaru Oinaga 5 months ago in reply to Youhao Xi

TI__Intellectual 2490 points

Hi, Youhao,

FYI, we came to the conclusion to use UCC256602-Q1 instead which can support Half-Bridge IPPC-CLLC topology to convert from 800V/400V to 12V.

Best Regards,
Masaru

0 Youhao Xi 5 months ago in reply to Masaru Oinaga

TI__Guru 72845 points

Hi Masaru,

Thank you for the updates. I think you are on the right path :-). Lets' close this thread here.

Good luck.

Best Regards,

Youhao

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LM25185-Q1: Using LM25185-Q1 as a controller for converting 400V/800V to 12V