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Default ON and toggle OFF with Big Pushbutton Power Switch



I have a couple of the Big Pushbutton Power Switch - https://www.pololu.com/product/2813, that I’d like to use it as a on/off + disable switch for an ESC for a RC-controlled model car. The ESC has no on/off slide switch.

Is there a combination of signals for the ON, OFF, and CTRL pins that will allow me to:

  1. default the power switch to the ON state once power is supplied
  2. be able to turn OFF the power switch via an external signal
  3. be able to turn ON the power switch again via an external signal

I’ve tried supplying a constant HIGH on ON, which fulfills 1) but it seems to override any control signal from the OFF/CTRL pins.

Another option is to provide a constant HIGH on CTRL, and supply the control signal via the OFF pin, but the product page seems to warn against it.

I’d appreciate any ideas, thanks!



There is not really a way to change whether our pushbutton power switch is on or off by default when power is connected, but bringing either the IN or CTRL pins high once you power it on should result in basically the same affect. Please note that the ON, OFF, and CTRL pins are intended to be used with short pulsed signals and not to be held in either a high or low state for an extended period of time. If you are using a microcontroller to control the switch, a simple way to get the behavior you want is to use two I/O pins, one each for ON and OFF, and send a high pulse to the on pin as soon as your microcontroller’s program starts running.

As you mentioned, you should never apply a high signal to both the CTRL and OFF pins at the same time; that would cause a short circuit. You can see this in the input structures diagram for the two pins:

When OFF is high, the transistor connected to CTRL will be on and the CTRL pin will be connected directly to ground.