Arduino: Sequential Brake TS Flasher 4: Pch Mosfet HighSide Switch
Specification creep… the intended LED modules are Common-Cathode so a High-Side Switch is required. Here I used a P-channel Mosfet to perform the HSS function.
In addition I used an optoisolator to isolate the mosfet Gate from the Arduino Pro Mini.
In this case I’m still powering the high-side-switched LED from the Arduino’s 5V regulated output rather than the vehicle’s 12 volt supply, so we aren’t fully isolated yet.
In practice the P-ch mosfet would be switching the 12-14 V from the main vehicle power bus to the LEDs, and also it would be using the same power source for the Gate signal from the optoisolator.
Here, for demonstration purposes, I’m just using the 5V regulated output of the ProMini for both tasks. The IRF9540N switches just fine on the 5V signal to the gate.
