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LM25011 shutdown circuit

Doane Arnold
Intellectual 335 points
Other Parts Discussed in Thread: LM25011

I would like to be able to shut down the LM25011 regulator from my microcontroller. The datasheet for the LM25011 states the shutdown threshold to be 70mV minimum. Is that the required voltage threshold to shutdown the part? What would you recommend for a circuit to guarantee remote shutdown. My controller is running at 3.3VDC.

Thanks, Doane

  • 0
    TI__Intellectual 1435 points

    The best approach to shutdown the LM25011 is an open drain N-channel MOSFET connected to the SS pin.  If your microntroller has an open drain output (no pull-up device), that output could be connected directly to the SS pin of the LM25011.   If the micro doesn't have an open drain output, you could drive a small discrete MOSFET with the 3.3V output from the micro.

    When the MOSFET is turned on by the microcontroller,  it will sink the 10uA pull-up current of the SS pin and force the SS voltage below the shutdown threshold.  This threshold is nominally 140mV and worst case 70mV.  The datasheet provides a graph of temperature dependence of the shutdown threshold  which indicates that lower threshold values occur at low temperatures.  See Figure 13

  • 0 in reply to David Pace
    Intellectual 335 points

    Thanks David. I'll try using one of the open-drain outputs.

    Doane