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BQ2423n / Switch off battery

Daniel PUIGSECH
Prodigy 40 points
Other Parts Discussed in Thread: BQ24230, BQ24232

Hi

I'm working on a battery charger based on the BQ24230 or BQ24232 (the choice is not finalized) but I would have a précision. In my project, I want the battery will be disconnected if the voltage rise to the cut-off value. Reading the datasheet on page 8, is that Q2 is off. So Pin OUT is over and the load is switch off. Reading the datasheet, I'm not sure this condition is made by the chip. Can you confirm this point.

Kind regards

Daniel

 

  • 0
    TI__Genius 13700 points

    Hello Daniel,

    I am not sure i understand your question.

    Are you asking if Q2 will open if the input voltage exceeds the OVP value? When an OVP case is detected Q1 will open to protect the downstream system and the battery but the OUT will be shorted to the battery through Q2.

    However if you are asking if Q2 opens when the battery charging has terminated by finishing the current taper while the battery is at the regulation voltage the answer is YES. Looking at the flowchart on Pg. 20 of the datasheet you can see that the BATFET is turned off if the charge has terminated while the adapter is still attached. However once the adapter is removed or the battery voltage dips to low the BATFET will close again.

  • 0 in reply to Ryan May
    Prodigy 40 points

    Hello Ryan

    Sorry, I have to precise my interrogation.

    What I want is to switch off the battery from the load when the V BAT  reaches the CUT-OFF voltage (approx. 3V). To do this, in the chip Q2 must be OFF. As I discuss with battery suppliers, the circuit is integrated in the battery pack, but in case of not, I would like to know if the bq2423n can do this by monitoring V BAT.

    I hope this is more clear for you now.

    Thank so much for your help.

    Daniel  

  • 0 in reply to Daniel PUIGSECH
    TI__Genius 13700 points

    Hello Daniel,

    Understood.

    There is no battery over-discharge protection incorporated into the BQ2423x family.

    This other E2E post provides a possible solution to add and battery undervoltage cut-off using a voltage supervisor to monitor the battery voltage and disconnect the battery.

    http://e2e.ti.com/support/power_management/battery_management/f/179/t/347974.aspx

  • 0 in reply to Ryan May
    Prodigy 40 points

    Ryan

    Thank you very much for your help.

    I'm going to read this article with great care.

    Kind regards

    Daniel