Low Side vs High Side Drivers

Background

Can be used as a high-side switch using a MOSFET gate driver for high amperage switching scenarios
Lower resistance than high-side

Generally driven by open-drain output pin due to pull-up resistor
Logic is backwards, to turn MOSFET on you ground the gate (send 0 to pin). To turn it off, you leave the pin as floating (for open-drain pins, this is done by sending it a logic 1)
Can use N-type transistor if the control voltage is higher than the load voltage (usually requires some circuitry to boost this voltage)

Can generally drive load from a microcontroller output as long as the logic level is higher than gate voltage of MOSFET
If a short-to-GnD fault occurs, the load is permanently on (no immediate danger)

Not good at supplying power to other circuits because GnD ref for driver circuit is above the real GnD by the amount of the voltage drop across the MOSFET
If a short-to-supply fault happens, load is shorted to supply (requires protection)

If a short-to-supply fault happens, load is permanently on (no immediate danger)
Obtain a true ground reference
Requires only 1 fuse for protection, low side requires 2

If Vdd is more than 0.6V higher than supply voltage for microcontroller, this can damage the microcontroller (e.g. microcontroller uses 5V supply and Vdd is 12V)

To avoid this, use a small N-channel MOSFET, whose outputs feeds the gate of the High-Side P-channel MOSFET

If a short-to-GnD fault occurs, the load is shorted to GnD which can be dangerous (requires protection circuitry)
Design is more complex than low-side, usually need another transistor driving the main P-channel MOSFET

Low-Side

High-Side

- Driving LEDs, relays, motors

- High current applications

- PWM control

- Turning power rails on and off

- Delivering power to entire circuit or voltage sensitive device

- Loads that require true ground