Does your microcontroller need to control a high-voltage item, like a 12V LED strip, while also needing to be powered? Do you want to avoid having multiple power adapters and microcontrollers for your project? The MOSFET Power Switch and Buck Regulator (Low-Side) is one product we needed at SparkFun, so we figured other folks might have the same problem. Power the board with up to 12V and control up to 10A, all while providing a sweet 3.3V to your control board.

The SparkFun MOSFET Power Switch and Buck Regulator (Low-Side) combines two circuits into one board: an LMR14203 buck regulator configured to output 3.3V and an N-channel MOSFET (PSMN7R0-100BS) configured as a low-side switch. A flyback diode is also on the load side for devices with back EMF! Simply pull the CTL pin low to activate the load.

Various connectors (barrel jack, female header, and poke-home) are provided to connect a power supply to a microcontroller of your choice (Arduino, micro-bit, Raspberry Pis microcontroller) and load them together. VCC, 3.3V, CTL, and GND are also broken out through 0.1″ spaced PTHs for those who prefer to solder. Two LEDs (PWR_LED and ON_LED) indicate when there is 3.3V and whenever power is applied to the load. Jumpers are included on the back to disable the LEDs. A MEAS PTH jumper is also included for those interested in precisely measuring the current consumption of the system.

Note: While the MOSFET is rated to 100A/100V, we don’t recommend you go much above 10A as the PCB polygon pours and traces become the limiter.

Get Started with the Sparkfun Mosfet Power Switch and Buck Regulator Guide

Features

• Input Voltage Range: 4.5V to 12V
• LMR14203 Step Down Voltage Regulator
  • Configured to Output 3.3V/300mA
• PSMN7R0-1000BS N-Channel MOSFET
  • Configured as a Low-Side Switch
• Connectors
  • Input: 5.5mm x 2.1mm Barrel Jack (Center-Positive)
  • Output: Poke-Home Connectors
  • Control: 1×4 Female Headers
• 0.1″-spaced PTHs
• Built-in Flyback Diode on Load
• LEDs
  • PWR
  • ON
• Jumpers
  • PWR_LED
  • MEAS
  • ON_LED
• Dimensions: 1.50″ x 1.50″ (38.1mm x 38.1mm)
• Weight: 9.9g

Resources

• Schematic
• Eagle Files
• Board Dimensions
• Hookup Guide
• Fritzing Part
• Datasheet
  • LMR14203
  • PSMN7R0-100BS
• GitHub Hardware Repo