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BQ25700A: Series resistor on SRP pin and SRN pin

Tamio Yokokura
Expert 3970 points
Part Number: BQ25700A


Hi, Support team,

The datasheet is mention as follows;

10Ω series resistor on SRP and SRN is for protection when battery pack is reversely inserted to connector.

Recently, a cell voltage is 4.40V/cell. As the result,the charging voltage is 17.6V if cell structure is 4-cells.

Can 10Ω series resistor protect from IC damage if 1.76A(=17.6V/10Ω) flows from GND to SRN or SRP as follows?

And also, I would like to know the maximum current that can flow through the internal diode.

Thanks

T.Yokokura

  • 0
    TI__Guru 56650 points

    SRP or SRN pin should be damaged with 1.76A on it.

    For the real battery application, the battery pack internal short protection circuit could be triggered before SRN or SRP pin get damage. The 10ohm SRP or SRN series resistors just give extra SRN or SRP current ramping up delay time before the battery pack's internal protection circuit turns off the battery voltage output.

    Also, the SRP or SRN series resistor could be damaged/disconnected before SRP or SRN pin gets damage. After SRP/SRN series resistor is disconnected, the SRP or SRN pin get protection.

  • 0 in reply to Wang5577
    TI__Expert 3970 points

    Thank you for your support.

    How much is the continuous(constant) current not to damage the internal diode on SRP and SRN pin? 

    I would like to know the value in the design.

    Thanks

    T.Yokokura