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BQ40Z50-R1: PACK+ goes to zero

JDrulia
Intellectual 385 points
Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQ40Z50EVM-561, BQ40Z50-R2

My design is based off the bq40z50EVM-561.

I am seeing voltage at Pack+, but when I plug an electronic load (for testing) to P+/- the voltage drops to the mV range. Why? The load is not enabled, voltage just drops upon immediate connection. I have double check that the electronic load is working fine. The output is not shorted. IT is enabled. FETs are enabled.

I have attached a log file.

Pack plugin.xlsx

Thanks in advance.

  • 0
    TI__Mastermind 25955 points
    Hi JDrulia,

    Please press the Wake pushbutton switch to temporarily connect BAT+ to PACK+. This will apply voltage to the PACK pin on the bq40z50-R2 to power-up the regulators and start the initialization sequence.

    You should see the Voltage come back :)

    To start a charge or discharge test, connect the SYS PRES position on the J3 terminal block to PACK-. If you have NR bit set to 1, you can leave the SYS PRES pin open.

    Sincerely,
    Bryan Kahler
  • 0
    Intellectual 385 points

    Just in case this may help someone else-

    I had a pinout issue with Q4. Drain and Source were swapped causing Pack+ to drop to zero (presumably through backwards Q4). I corrected that, and the issue is gone.