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[FAQ] TPS650830: Is a series resistor needed on the VBATTBKUP?

Part Number: TPS650830

Is a series resistor needed on the VBATTBKUP?

  • A: If the VBATTBKUP is being used with a coin-cell battery as intended then, a series resistor is required to protect the coin-cell battery from excessive discharge current. The equation below shows how to calculate the resistor needed.

    Minimum R = Max Vbatt / Imax_discharge_spec

    Where: The max discharge current is usually specified in the coin-cell battery datasheet.

    Cases where resistor is not required:

    If the VBATTBKUP feature is not used then, the VBATTBKUP pin may be floated and therefore no resistor is required.
    If the VBATTBKUP is supplied from some other type of source like an LDO then no resistor is required because, there would be no coin-cell battery to protect.