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Original question:

BQ24610: LODRV MOSFET blowing on battery plugin

BQ24610: LODRV FET issue

Bernhard Rieder
Prodigy 10 points
Part Number: BQ24610


Hello,

I had troubles with current inrush and the LODRV MOSFET, burning the inductor and the current measurement shunt. However i found the proposed solution with the diode in the forum here https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1446404/bq24610-lodrv-mosfet-blowing-on-battery-plugin?tisearch=e2e-sitesearch&keymatch=BQ24610

As far as connecting the battery it works. However, the charging current is very low now and the charge LED flickers. Is there a way to get the solution with the Schottky diode working? I plan a redesign but still want to use the diode because not using it seems to risky for me, because the 4 batteries are on the board, GND of the battery is directly connected to the ground plane and the connection to VBAT+ is a very short and wide trace, too. I do not see much way of improvement and reducing the inductance here.

Also I mounted the diode between the current shunt and the inductor because this was the only feasible way to apply it as a hardware path to my prototype board. As a reference I add the shematic hereimage.png

To summarize, my questions are:
1) Is there a way to get the charger working using the diode (without it seems to risky for me)

2) Are there some issues with my design I did not see and which causes the current inrush?

 

Best Regards,
Bernhard

  • 0
    TI__Mastermind 37301 points

    Hello Bernhard,

    I do not recommend placing the diode between the Inductor and the sense resistor. The diode is affecting the charge current sense measurement and this is why you are seeing the low charge current. The diode should be placed after the sense resistor.

    Best Regards,

    Christian.

  • 0 in reply to Christian Moyer
    Prodigy 10 points

    Hi Christian,

    The solution in the shematic is based on the fact that this was the only viable solution for a hardware-patch on the current PCB without a redesign.

    So if I understand you right R316 and R371 should be connected to the anode and Q304, C317, C318 and PACK+ schould be connected to the cathode? If i understood the soullution with the diode correctly I should place a new capacitor on the anode side as well? Which value would you recommend?

    Best Regards,

    Bernhard

  • 0 in reply to Bernhard Rieder
    TI__Mastermind 37301 points

    Hello Bernhard,

    Bernhard Rieder said:
    So if I understand you right R316 and R371 should be connected to the anode and Q304, C317, C318 and PACK+ schould be connected to the cathode? If i understood the soullution with the diode correctly I should place a new capacitor on the anode side as well? Which value would you recommend?

    I recommend using a 10uF cap.

    Best Regards,

    Christian.

  • 0 in reply to Christian Moyer
    Prodigy 20 points

    Hi Christian,

    I have the same problem as Bernhard.

    I made the modifications you suggested and inserted a diode (PMEG6020ER) in the place you suggested.
    The main problem seems to be solved, but now the charging current is incorrect.
    Instead of measuring a current of about 500 mA, I measure about 90 mA.
    Briefly shorting the diode restores the correct current.
    Is it possible that the diode is interfering with the battery detection mechanism?
    Do you have a diode model to suggest?
    Thanks for your help.

  • 0 in reply to Marco Gazzi
    TI__Mastermind 37301 points

    Hello Marco,

    Can you please post a separate question along with your schematic?

    Best Regards,

    Christian.