• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 425 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ78350: Inquire BQ78350+BQ76930+BQ76200 SCH review and charge-pump issue

user4773172
Intellectual 1410 points
Part Number: BQ78350
Other Parts Discussed in Thread: BQ76200, BQ76930, BQSTUDIO

Hi Sir,

May I have your help to give us some suggestion about my customer issue as below:

My customer C-tech have three projects and use our BQ78350+BQ76930+BQ76200, please refer SCH in the attachment.

They facing an issue us BQ76200 charge pump work abnormal, it will not be active when re-boot the power.

The waveform in the attachment is 7 series application, yellow and blue is MOS gate voltage.

Also, they have another 14 series platform facing the same issue, they use BQStudio RESET command, and charge pump will not be active when re-boot the power, there will have high frequency switch noise during this status.

Could you kindly help to review the SCH first to see if there have any potential risk will cause this issue?

7S5P_BQ78350+76930-0626(ARTHUR) FOR SIMON.pdf7S5P_BQ78350+76930-0626(C-tech).pdf

Thank you.

Edward

  • 0
    TI__Guru* 80963 points
    Hi Edward,

    The best reference for debugging this issue is this app note: www.ti.com/.../slua794.pdf
    I don't know the cause of the issue, but here is our feedback on what we can observe from the schematic:
    - We would have expected some larger resistance at R16, R18 and smaller where you have the 620 ohm values. I think some FET suppliers recommend ~90% of the resistance should be on the common path.
    - The charge pump cap looks sized OK for the FETs, 4 at 4.2nF x 25 = 420 nF.
    - The C2 & C46 could be bad adding load, but they small and are shown as NC.
    - C14 says it is the right value.
    - Perhaps something was substituted or shorted in assembly.
    - For debug you might connect PACK+ to VP+ to see if it turns on, that might indicate a problem bringing up PACK+. Or if you could separate CHG_EN from DSG_EN.

    Best regards,
    Matt