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BQ24618: BQ24618 BATDRV

Prathamesh Tadaka
Prodigy 185 points
Part Number: BQ24618

Hello,

I working on 3s li-ion charger. I have build circuit of bq24618 ic as per given in the datasheet. bq24618 works well but without BATFET mosfet. If i used BATFET mosfet high current flow through it and dameged Q4 ,Q6 MOSFET? I didn't understand why these damaged. What will be reason?

  • 0
    TI__Mastermind 24075 points

    Hi Prathamesh,

        The intrinsic body diode of the BATFET, and the HSFET should block current flowing from the adapter to the battery when converter is disabled. What is the load on your system? If you have a short on SYS, this could cause the adapter voltage to sag, which turns on BATDRV and would damage those FET as current could be dumped through the body diode of the 2 FETs. Try testing normal operation with BATFET with system load removed. If this works, include a safe constant current load at SYS and observe operation.

         If damage occurs consistently I would recommend obtaining an EVM to test ideal BQ24618 configuration to verify as well.

  • 0 in reply to Kedar Manishankar
    Prodigy 185 points

    Hi Kedar,



                    I tested this without load. As soon as i connect adapter to charge large current flow through it and damaged mosfet.



    Regards,

    Prathamesh

  • 0 in reply to Prathamesh Tadaka
    TI__Mastermind 24075 points

    Hi Prathmesh,

       Electrically this should not be possible unless 

    • There is improper solder causing a short
    • You have reversed the drain and source of either of the switching MOSFET

    Post is labeled BATDRV issue, but do you actually see BATDRV ever coming on? Issue with the IC would only be if you saw both ACDRV and BATDRV on at the same time, which would not happen.