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BQ20Z45-R1 PRES pin function

1567623
Intellectual 330 points
Other Parts Discussed in Thread: BQ20Z45, BQ20Z45-R1, BQEVSW

Hi 

We are working on smart battery (which is based on BQ20z45-R1) & using LTC4100 battery charger & external mcu. Now we are facing problems that  battery is not charging or discharging. We had given 3.3V signal from MCU to PRES pin (pin no 12) of BQ20Z45  & noticed that absolute max. vtg rate of PRES pin is 2.8V.

My question is will this cause to damage of this IC pin?

What are the possible reason to behave the IC like this?

  

 

  • 0
    TI__Expert 3385 points
    Hi

    Yes, it is very possible that this could damage the IC. The pin functions such that if it is pulled to ground, the bq20z45 detects the system as present. The pin should never go beyond its abs max rating, and doing so may result in permanent damage of the IC.

    Best,
    Justin
  • 0 in reply to Justin Erfan
    Intellectual 330 points

    Thanks Justin.. 

    But we have posted one query related same issue in e2e forum but still not received any reply. Could you pls help on this. 

    Pls find below link (Explained problems in detailed)

    https://e2e.ti.com/support/power_management/battery_management/f/179/t/502672

  • 0 in reply to Justin Erfan
    Prodigy 50 points

    Hi Justin,

    In the above scenario of /PRES pin damaged, still SMBus module in the gas gauge will work?

    Regards

    SUNIL

  • 0 in reply to SUNIL P
    TI__Expert 3385 points
    Hi Sunil,

    I cannot guarantee that the device will still operate (or even communicate) after this damage. Easiest way to check would be to connect to bqEVSW and see if the device is detected; however, if the pin is damaged in the above scenario, it would be best to replace the IC.

    Best,
    Justin
  • 0 in reply to Justin Erfan
    Prodigy 50 points

    Hi Justin,

    Since we are working only with the battery pack, we don't have the access to the gas gauge inside the pack. The problem we are facing now is, we could not get the battery voltage at the terminals even if we pull the "/PRES" pin to GND. This could be due to the damage of "/PRES" pin. But we are able to communicate to the battery through SMBus and could read that battery has enough SOC in it . Please see the snap shot of the register values read through gas gauge evaluation software.

    Can you please inform whether there is a way to activate the battery pack if /PRES pin is damaged?

    Regards,

    SUNIL

  • 0 in reply to SUNIL P
    TI__Expert 3385 points
    Hi Sunil,

    I notice from your screenshot that your PRES pin is not being set. If you are pulling the pin low and still cannot get this bit to set, there could be an issue. There is a bit in Op Config B, [NR], which when it is set, it can ignore the physical pin's state. However, if the PRES pin is indeed damaged, it is likely you will not be able to charge or discharge, and the IC will need to be replaced.

    Best,
    Justin
  • 0 in reply to Justin Erfan
    Prodigy 50 points

    Hi Justin,

    We have tried to read the Operations Cfg B register, but it shows some error message while reading.

    Please find the attached screenshot.

    Regards,

    SUNIL