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BQ76940: ALERT-pin equivalent circuit

JAP
Intellectual 2410 points
Part Number: BQ76940

Dear Experts,

According to BQ76940 datasheet there is a pulldown resistor in ALERTpin.

When looking at equivalent circuit of ALERT-pin from SLVA682, pin seems to be push-pull type.
http://www.ti.com/lit/an/slva682/slva682.pdf

Could you explain the internal circuitry of ALERT-pin? Another thing, what is the current driving capability of ALERT-pin when driven high?

Thanks!

Rgds,

Juha

  • 0
    TI__Guru 54715 points
    Hi Juha,
    The ALERT pin driver is a push-pull as shown. It also has the input function shown on the left side of the figure. The pull down is weak, a high impedance driver. See the RALERT_PD specification in the electrical characteristics table of the data sheet. The author of the application note apparently considered the resistance part of the driver transistor.
    The ALERT pin does not have a specified maximum drive current. Note the VALERT_OH specification, it will output 75% of REGOUT or more with 1 mA output current.