UCD9248: Why 3.3V power is not generated by the NPN transistor and internal circuit of UCD9248.

Xiang Maverick

Part Number: UCD9248

In the attached schematic, VIND is 12V input power supply. VDD_UCD is expected to be 3.3V. But it is not. It is around 1.5V measured at the PCB board. Could you please find the reason and tell me? Thank you so much.7658.Power.pdf

over 6 years ago

0 Qian Chen over 6 years ago

TI__Mastermind 24075 points

Hello,

VDD_UCD is generated by a linear regulator.
Can you check the Q2 base and collector pin voltage? It better to use oscilloscope probe to check the voltage level and if the voltage is stable.

Thanks
Qian

0 Xiang Maverick over 6 years ago in reply to Qian Chen

Intellectual 750 points

Currently, I change my board using LDO to provide 3.3V power to UCD9248 to download firmware. I think I should follow your suggestion later.

0 Qian Chen over 6 years ago in reply to Xiang Maverick

TI__Mastermind 24075 points

Hello,

I'm going to close this post.
Please let me know if you need further support.

Thanks
Qina

0 Xiang Maverick over 6 years ago in reply to Qian Chen

Intellectual 750 points

Could this thread last for further 2 weeks? After I have 3 boards ready, I can test according to your suggestion?

0 Qian Chen over 6 years ago in reply to Xiang Maverick

TI__Mastermind 24075 points

Hello,

Per E2E policy, I have to close this post first.
If you need further support, you can reopen this post.

Thanks
Qian

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UCD9248: Why 3.3V power is not generated by the NPN transistor and internal circuit of UCD9248.