TRSF3223E: ASCII character issue from UART

Zhonghui Xu

Part Number: TRSF3223E

Hi team,

I got a question form VIP customer.

after some period of time, we began getting ASCI character issue or weird character displaying on our putty window. We believe that the C3/C4 caps 0.1uF(0201) 5%, 16V was not adequate considering the amount of ripple measured on seen V-/+ but mostly on V-. We doubled (2) C3/C4(V-/+) caps, 0.1uF(0201) 5%, 16V on both the V+/- and seems to be the fix on one board and used a higher voltage cap V- caps 0.1uF(0201) 5%, 25V which worked as well. Could you explain why this worked on the charge pump cap on V+/-?? Might be temperature related.

hope get answer.

thanks.

Best regards,

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 276230 points

"After some period of time" implies that the capacitors degraded over time. Can you measure the capacitance of those capacitors? What are the actual temperatures?

0 Eric Hackett over 3 years ago in reply to Clemens Ladisch

TI__Guru 69622 points

Clemens,

Thanks for the help here as always!

Zhongui,

As Clemens said, capacitances to degrade over time, but also over temperature and even DC bias. Make sure the capacitors chosen are sufficient for the temperature and DC bias of the application.

Regards,

Eric Hackett

0 Zhonghui Xu over 3 years ago in reply to Eric Hackett

TI__Expert 5445 points

Hi team,

thanks a lot.

Best regards,

Zhonghui

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TRSF3223E: ASCII character issue from UART