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BQ40Z50-R2: BQ40Z50-R2

Zhihan Zhang
Expert 1100 points
Part Number: BQ40Z50-R2

Hi,

I have some questions about BQ40Z50-R2's BAT, VCC, and PACK pins. According to datasheet, VCC and PACK source power from charger if present when BAT falls below VCC.

Does this mean if BAT is disconnected, without charger the IC will power down?

If BAT is disconnected, safety PTC protection will be disabled right? Will VCC or PACK be able to enable PTC function?

Please correct me if I understand wrongly. Thanks!

Best Regards,

Zhihan

  • 0
    TI__Guru 52115 points

    Hi Zhihan,

    We will take a look and get back to you.

    Andy

  • 0
    TI__Mastermind 34665 points

    Hello Zhihan,

    BAT is the default power for the gauge and the gauge will always switch to BAT power if the battery is connect and the battery voltage is above Vshutdown. 

    I'm guess you mean protection circuits by PTC. The gauge protection is to protect the battery, if there's no battery then there's no need for protection. In that case the protection FETs will be open.

  • 0 in reply to Damian Lewis
    Expert 1100 points

    Hi Damian Lewis,

    Thank you very much for your answer!

    I'm actually wondering about the situation that when the diode (D1 in DS) to BAT pin is open, so BAT pin is not available. In this case, without charger,

    1. Will VCC or PACK pin provide power to the IC? In DS, it says VCC and PACK source power from charger if present.

    2. If VCC or PACK can provide power without charger present, will PTC protection still be available? From schematic in DS, it seems PTC protection is enable through BAT.

    I would appreciate it if you could answer my questions!

    Best Regards,

    Zhihan

  • 0 in reply to Zhihan Zhang
    TI__Mastermind 34665 points

    Hello Zhihan,

    1. Yes the battery voltage will be feed through the body diode of the CHG FET to VCC. PACK is a voltage sense pin and doesn't power the gauge. VCC is the only secondary power. When power is applied from the PACK connector (say with a charger) the PACK/charger voltage will be feed through the body diode of the DSG FET to VCC.
    2. The protection wouldn't be available, since without BAT voltage the gauge interprets that the battery isn't present. Yes BAT being present is one of the checks the gauge does to close the protection FETs. Therefore with BAT voltage missing then the protection FETs will be OFF and remain OFF.