• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 265 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

BQ25121A: Behavior with battery disconnected

John Condon55
Prodigy 160 points
Part Number: BQ25121A

Greetings,

What is the expected behavior of the BQ25121A when the battery is disconnected, but an input charging voltage is supplied? I would expect that the Battery UVLO fault would trigger, but on our hardware we see the battery voltage jumping between 96-98% and no faults. Is there a recommend way to detect battery disconnection?

Thanks,

John

  • 0
    TI__Mastermind 21590 points

    Hello John,

    That is because the capacitor on the BAT pin is getting charged and discharged from the battery regulation voltage to thee battery recharge threshold.

    You can either disable charge through I2C or set /CD high. This will let you know when the battery is absent and show the BUVLO fault.

  • 0 in reply to Raheem
    Prodigy 160 points

    I set the /CD pin high while reading the STATUS, FAULT, and performing the battery voltage sample/read procedure. Unfortunately this had identical results where the the BUVLO fault was not set and the battery voltage. How long will I need to hold /CD high before the BQ25121A reacts?

    Below is a capture of the I2C, /CD, and Battery Voltage lines at two different time scales.

  • 0 in reply to John Condon55
    TI__Mastermind 21590 points

    Hello,

    You have to hold /CD high and hold for a few ms to see the BUVLO. The capacitor on the battery pin will also need to be discharged.