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Original question:

BQ2980: Shutdown function of CTR-Pin

BQ2980: Reset via button possible?

Florian Zierer
Prodigy 50 points
Part Number: BQ2980

I would like to use a push button for a reset functionality but want to ensure the device does not get into SHUTDOWN.

I was thinking about connecting CTR (with a pull down to PACK-) via a push button to PACK+. So if the button is pushed, the CTR should turn the CHG and DSG off and thus also disabling PACK+.

As PACK+ is turned off, the voltage on CTR should be down to PACK- due to the pull down.

Is this possible or are there any things I should consider?

Can my solution have any oscillating issues?

  • 0
    TI__Genius 11315 points

    Hey Florian,

    The DSG and CHG FETs will turn back on if CTR drops below V(IL) within 3.6 seconds. It seems that you would have an oscillating system. You could connect the push button directly to BAT+. Make sure the loop terminates at BAT-.

    Thanks,
    Caleb

  • 0 in reply to Caleb Perez
    Prodigy 50 points

    Hi Caleb,

    the button shall be pushed manually so I can't implement any timing restrictions here.

    If I connect it to BAT+, there is the risk, that the button is pressed too long and that shutdown is entered instead of reset.

    How would you suggest to terminate the loop?

  • 0 in reply to Florian Zierer
    TI__Genius 11315 points

    Hey Florian,

    There is a risk that the button being held too long would cause it to shut down. I would suggest you find a button that cannot be held down, so that it only sends a pulse to the CTR pin. Terminate the loop past the sense resistor so that current from BAT+ doesn't affect current measurement.

    Thanks,
    Caleb