How to find the right MOSFET Transistors AI guide

What the AI looks for in MOSFET Transistors

Logic-level gate drive

Rds(on) must be specified at or below your actual gate voltage, for example 4.5 V for 5 V logic and 2.5 V or lower for 3.3 V logic. Vgs(th) is only where conduction starts. A MOSFET driven near threshold is barely on and overheats.

Drain-source voltage (Vds)

Choose Vds with clear margin above the bus voltage, including ringing and inductive spikes. Overvoltage avalanche is a leading failure mode in motor and solenoid circuits.

Real on-resistance and heat

Estimate conduction loss as I² times Rds(on) at your gate voltage and at a hot junction temperature, then check against package thermal resistance. Rds(on) rises significantly with temperature, and headline current ratings assume an ideal heatsink.

Gate charge vs switching frequency

At higher PWM frequencies, compare total gate charge (Qg) with your driver's current capability. Slow gate transitions cause switching losses that can exceed conduction losses.

Gate voltage limit

Check Vgs(max) for the specific part. Some logic-level parts have a lower gate limit and are easily damaged by overdrive or transients.

Channel type

Use N-channel for low-side switching. Use P-channel, or N-channel with a high-side driver, for high-side switching. An N-channel on the high side needs a gate voltage above the supply rail.