MOSFETs

What is a MOSFET?

A MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is a voltage-controlled field-effect transistor. With high input impedance, it requires very low drive current and is widely used in switching and amplification applications. It comes in two main types: N-Channel and P-Channel.

MOSFET Types and Selection Criteria

Our catalog includes power MOSFETs (such as IRFZ44N, IRF530, IRF3205), logic level MOSFETs (IRL series), and models in both surface-mount (SMD) and through-hole (THT) packages. When selecting a MOSFET, the key parameters to consider are:

• V_DS (Drain-Source Voltage): The maximum voltage the MOSFET can block. Choose a rating 20-30% higher than your application's voltage.
• I_D (Continuous Drain Current): Continuous current carrying capacity. Current decreases with temperature, so a safety margin is essential.
• R_DS(on) (Drain-Source On Resistance): This resistance determines conduction losses; lower is better for reduced heat, especially in switching power supplies and motor drivers.
• V_GS(th) (Gate Threshold Voltage): The threshold at which the MOSFET starts turning on. For direct drive from microcontrollers (3.3V/5V), a logic-level MOSFET is necessary.
• Gate Charge (Qg) and Switching Speed: In high-frequency PWM applications, gate capacitance (Ciss) and total gate charge directly affect switching losses.
• Package Type: Power packages like TO-220, TO-247 allow heatsink mounting; SMD packages like DPAK, SOIC-8 save board space.

Applications

MOSFETs are used in a wide range of applications from low-power signal processing to high-power industrial drives. Common uses include:

• DC motor drivers and H-bridge circuits
• Switch-mode power supplies (SMPS) and DC-DC converters
• LED lighting control and PWM dimmer circuits
• Relay and solenoid drivers
• Battery protection and charging circuits
• Instrumentation amplifiers and audio amplifiers

To choose the best MOSFET for your application, clarify your voltage, current, switching frequency, and drive voltage requirements. If you're unsure, the widely used N-Channel IRFZ44N (for low-voltage switching) or IRF530 (for medium power) are excellent starting points.