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BQ25175: Charging permanently disabled/damaged after battery removal

MUHAMMAD ASIM ZIA
Prodigy 10 points
Part Number: BQ25175


Tool/software:

Hi TI, I recently had an experience where the system functioned correctly, fast charging at 3V for 1S1P, 1S2P battery configurations.



However, during my testing, I disconnected the battery connector while the USB was connected. After this, the system stopped charging. 0V on ISET, 0V on TS. No matter what i do, its in a permanent state of failure. Can you help me understand whats happening? I initially believed that this is a simple safety timer fault, however, now Im thinking that due to disconnecting battery and keeping the USB connected, i might have permanently damaged the internal circuit. 

  • 0
    TI__Guru* 76516 points

    Hello

    Disconnecting the battery should not damage the unit, input is rated to 30V and output is rated to 13V.  Input power Off/On should restart unit, also pulling TS pin low then release will rest unit.

    Is the TS Pin connected only to R4 and U1, no NTC or connection to battery pack?

    Are you seeing this will mult units or only one?

  • 0 in reply to Bill Johns
    Prodigy 10 points

    Hi Bill, ts is pulled down by 10kOhm resistor. Have an FET to force it off. I tried toggling the TS, did not work either. Feels like permanent damage; this has happened on 2-3 units. 1 completely stopped showing signs of life, the other two only charge above 3V.

  • 0 in reply to MUHAMMAD ASIM ZIA
    TI__Guru* 76516 points

    Hello

    I am setting up some test here and will update you tomorrow.

    The input voltage is 5V, right?

    Battery voltage during your test is 3V?

    The problem is occurring below the max charge voltage of 4.35V?

  • 0 in reply to Bill Johns
    Prodigy 10 points

    Test setup:

    Input 5V USB.

    The battery was at 3V.

    Test 1, pulling the USB out during charging.

    Test 2, inserting USB without any battery on.

    Outcomes: Battery charger gets permanently damaged/charging behaviours change

  • 0 in reply to MUHAMMAD ASIM ZIA
    TI__Guru* 76516 points

    Hello

    i have tested this condition in the lab on an EVM, multiple cycles and do not see fails.

    Would like to get more information on your system.  We can set up a private conversation using the PM feature of the forum.  Look for a request from me.