Contents
Simple MOSFET transistor circuits allow you to turn ON or OFF electrical devices, instruments and embedded systems with the touch of a button. Sometimes you want to be able to toggle an electronic instrument ON or OFF by momentarily pushing a single button.
A short button press applies power, a subsequent press initiates orderly shutdown under control of the microcontroller, and a long button press forces power-down. The microcontroller instrument can also turn itself OFF by setting an output pin.
How does a push button on / off power switch work?
Fig. 1 Circuit schematic of a latching push button ON/OFF power switch for a microcontroller based product, allowing the microcontroller to turn itself OFF. In this circuit, a momentary button press turns ON power to the microcontroller, and latches it ON. A second press can initiate shut down, or the microcontroller can turn itself OFF.
How does a p-channel MOSFET turn on?
2) The P-Channel MOSFET turns on when its gate is negative relative to the source. When you press the button, the gate of the MOSFET is pulled to GND, allowing current to flow to the VIN pin, which will power the microcontroller. This happens as long as the MOSFET’s gate is pulled to GND.
Push Button ON/OFF Power Control Using MOSFETs Simple MOSFET transistor circuits allow you to turn ON or OFF electrical devices, instruments and embedded systems with the touch of a button. Sometimes you want to be able to toggle an electronic instrument ON or OFF by momentarily pushing a single button.
How does the power switch work on a N-MOSFET?
While it is ON, pressing and holding the button for more than 3 seconds turns the power switch back OFF, and it stays OFF until the next momentary button press. For it to reliably turn OFF, the load should draw sufficient current so that any downstream capacitors will discharge within a few seconds, allowing the gate drive of the N-MOSFET to decay.
How are MOSFET transistors used in microcontrollers?
Here you’ll find several application notes describing micropower latch switch circuits that detect a button press and switch ON and OFF the main power to your embedded system or microcontroller project using high-side MOSFET transistor switches.