The Adafruit Push-button Power Switch is a tidy little design that
lets you control a DC power source using an everyday tactile button.
The breakout uses a latching analog circuit that is triggered
push of the button. Press once to turn on, then press again to turn
off. The circuit uses a 3A P-FET to connect and disconnect the IN pin
to the OUT pin. Works great from 3V to 14VDC and up to 3A (although
the FET gets a little toasty at continuous 3A draw) yet has only 0.5uA
quiescent current draw.
Using it is easy: connect the power source to Ground and IN, then the
load from Ground to OUT. We include a 12mm tactile switch that works
well but you can solder in your own switch as well. Press the button
(or short the button pins) to alternate between on or off. A on-board
red LED will light up when active so you know its working. There's a
fourth KILL pin, which you can use to turn off the load and/or keep it
off even if the button is pressed. When 1 or more volts is applied it
will instantly turn off the FET. This allows your project to turn
Comes with a assembled & tested bread-board friendly breakout board
with four mounting holes, a 12mm tactile button, and some 0.1" male
header you can solder to the board to plug it into a breadboard.
The power switch is an elegant way to control power to your project,
but there are some things to keep in mind: since there is a pass FET,
this is only for 3-14V DC voltages. This is not a mechanical switch so
there is no air-gap isolation. There is a 'body diode' in the pass FET
so if the load has a voltage on it that is higher than the input
voltage, current will flow back to the input. There is built-in
debouncing but very bouncy switches can be annoying as they will turn
on and off fast instead of latching. Details:
* Dimensions: 20.51mm / 0.8" x 17.75mm / 0.69" x 2.66mm / 0.1"
* Height with Switch: 8.69mm / 0.34"
* Weight: 2.6g