UCC256303: Start-up fails when high humidity

Kazuki Itoh

Part Number: UCC256303
Other Parts Discussed in Thread: UCC256403

Hello team,

Could you please help me to address UCC256303 start-up issue under high humidity?

Please find internal link here for detailed issue description, schematic and waveforms. (Please connect to VPN for download)

It includes 5 questions from my customer.

Regards,

Itoh

over 4 years ago

0 Yunsheng Qu over 4 years ago

TI__Genius 9790 points

Hi, Kazuki

It is the first time to see this phenomenon, please give few more days to dig in.

BTW, is that possible to change UCC256303 to UCC256403 which is the upgrade version and it is easier to debug and has higher noise immunity. Here is migrating guideline from UCC256303 to UCC256403.

https://www.ti.com.cn/cn/lit/an/slua966a/slua966a.pdf?ts=1611746617452&ref_url=https%253A%252F%252Fwww.ti.com.cn%252Fproduct%252Fcn%252FUCC256403

Yunsheng

0 Kazuki Itoh over 4 years ago in reply to Yunsheng Qu

TI__Genius 10730 points

Hello Yunsheng-san,

Thank you for taking a look at the issue.

OK. I'd appreciate if you address the issue in this week.

Regards,

Itoh

0 Kazuki Itoh over 4 years ago in reply to Kazuki Itoh

TI__Genius 10730 points

Hello Yunsheng-san,

A have two additional questions.

6. Could you please provide more detailed BLK pin internal circuit to understand this issue?

7. Could you please let me know the input impedance of the BLK pin?

Regards,

Itoh

0 Yunsheng Qu over 4 years ago in reply to Kazuki Itoh

TI__Genius 9790 points

Hi, Kazuki-san

Could you let me know what is failure rate of this issue?

Can you see the failure if you change the chip to another date code?

I suggest you to submit the FA process.

Yunsheng

Power management

Power management forum

UCC256303: Start-up fails when high humidity