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Original question:

BQ76920: Is the Alert-Pin an Open-Drain output?

BQ76920: Is Alert pin damaged when MCU always pull it down?

David Yang2
Intellectual 320 points
Part Number: BQ76920


Hi,

The Alert pin is connected to MCU as below.

MCU would always pull Alert pin down. Is Alert pin damaged? the maximum current from BQ76920 Alert pin?

Best regards,

  • 0
    TI__Mastermind 42535 points
    Your question has been assigned to an AE. It will be answered shortly.
  • 0
    TI__Guru 54715 points
    Hi David,
    ALERT is a push-pull driver with input as shown in the figure of the apnote www.ti.com/.../slva682. In the bq76920 data sheet a maximum current is not specified, but it is not recommended to be pulled down. Current from the pin will depend on the strength of the specific driver transistors, it is not a characterized data sheet parameter. The output high level is specified at a 1 mA load, output current from the pin will come from the battery and a high current is generally undesired in the system.
    Notice that the internal pull down resistance RALERT_PD is large even when combined with the recommended external RALERT, it should be easy to select a series resistor as you show above to limit the current while providing suitable signal levels to the bq76920 and MCU.