IRFZ44N MOSFET Specifications and Applications

ElecSuppliers Part Number GuideSep 25, 2026

IRFZ44N is a single N-channel power MOSFET designed for high-current switching and power control applications. The device is associated with the International Rectifier IR MOSFET family and is currently listed by Infineon as an active product. It uses a TO-220 package and is specified for a maximum drain-to-source voltage of 55 V.

The IRFZ44N combines a relatively low on-resistance with high current capability, making it suitable for applications such as DC motor control, power supplies, inverters, load switching and battery-powered equipment. Infineon identifies the device for applications including DC motors, inverters, SMPS, lighting, load switches and battery-powered systems.

IRFZ44N Key Specifications

The IRFZ44N has a maximum drain-to-source voltage of 55 V and a maximum continuous drain current of 49 A at a case temperature of 25°C. The maximum continuous current is lower at elevated case temperature, with the datasheet specifying 35 A at 100°C.

The maximum static drain-to-source on-resistance is 17.5 mΩ when the gate-to-source voltage is 10 V and the drain current is 25 A. The relatively low RDS(on) helps reduce conduction losses when the MOSFET is fully enhanced.

Other important specifications include a maximum gate-to-source voltage of ±20 V, a gate threshold voltage range of 2 V to 4 V and a maximum junction temperature of 175°C.

The IRFZ44N is specified with a total gate charge of 63 nC under the conditions given in the datasheet. Gate charge is an important parameter when the MOSFET is driven at higher switching frequencies because it affects the requirements placed on the gate-driver circuit.

IRFZ44N MOSFET Characteristics

The IRFZ44N is an N-channel enhancement-mode power MOSFET. Its drain-to-source current is controlled by the voltage applied between the gate and source terminals.

When the gate-to-source voltage is sufficiently high, the MOSFET enters a low-resistance state and allows current to flow between drain and source. When the gate voltage is removed or reduced below the required drive level, the MOSFET switches toward the off state.

For the specified 17.5 mΩ maximum RDS(on), the datasheet condition uses a 10 V gate-to-source voltage. This is important when designing a control circuit because the IRFZ44N should not automatically be treated as a logic-level MOSFET suitable for full-current operation from every low-voltage microcontroller output.

IRFZ44N RDS(on) and Power Loss

RDS(on) is one of the main parameters to consider when using IRFZ44N for power switching.

When the MOSFET is fully on, its conduction loss can be estimated from the relationship between drain current and on-resistance. As current increases, conduction loss increases rapidly, making thermal design increasingly important in high-current applications.

The 17.5 mΩ maximum value is specified at VGS = 10 V and ID = 25 A. Designers should therefore use the appropriate operating conditions from the datasheet when calculating real application losses rather than assuming that the maximum RDS(on) value applies identically under every gate-drive condition.

Temperature also affects MOSFET performance. The complete design should consider junction temperature, PCB or heatsink thermal performance and the actual duty cycle of the switching application.

IRFZ44N Gate Drive Requirements

The gate of the IRFZ44N is voltage controlled, but the gate still requires charge to transition between switching states. The total gate charge specified for the device is 63 nC under the datasheet test conditions.

For low-frequency switching, a simple gate-drive circuit may be sufficient in some applications. For higher-frequency switching, the gate driver needs to supply and remove charge quickly enough to control switching losses.

The 2 V to 4 V gate-threshold specification should not be interpreted as the voltage required for low-resistance operation at high current. Threshold voltage indicates the point at which a small drain current is established under the specified test condition. The RDS(on) specification, in contrast, is given at VGS = 10 V.

This distinction is important when considering IRFZ44N for microcontroller-controlled circuits.

IRFZ44N Package and Thermal Design

IRFZ44N is available in a TO-220 package. Infineon lists the device with through-hole mounting and a maximum power dissipation specification of 83 W on its current product information.

The TO-220 package is widely used in power electronics because it can be mounted directly to a heatsink when additional thermal management is required.

The actual power that can be dissipated in an application depends on the thermal resistance between the junction, package, heatsink and surrounding environment. A design operating close to the maximum current rating may therefore require a suitable heatsink or additional PCB thermal management.

IRFZ44N Body Diode

Like other power MOSFETs, IRFZ44N contains an intrinsic body diode between the source and drain. The datasheet specifies a continuous source current of 49 A for the body diode and a maximum pulsed source current of 160 A under the specified conditions.

The body diode can conduct current when the circuit operates in the reverse direction relative to the MOSFET's normal channel conduction. Its forward voltage, reverse recovery time and reverse recovery charge can become important in switching applications.

For designs involving synchronous switching, inductive loads or high-frequency power conversion, the body diode characteristics should be considered together with the external circuit.

IRFZ44N Switching Applications

IRFZ44N can be used in a variety of power switching circuits where its 55 V voltage rating and high-current capability are appropriate.

DC Motor Control

The device can be used as a switching element in DC motor control circuits. PWM control can be applied to the gate to regulate the average voltage or current supplied to a motor.

When used with an inductive motor load, the circuit should include an appropriate current path for inductive energy and should be designed around the MOSFET's switching and thermal characteristics.

Power Inverters

IRFZ44N can be used in low-voltage inverter circuits where multiple MOSFETs are configured to switch current through a transformer or other load.

The voltage and current requirements of the complete inverter must be evaluated because the 55 V drain-to-source rating limits the allowable operating voltage and transient margin.

Switching Power Supplies

The device can be used in certain SMPS and DC-DC converter designs. Its low RDS(on) can help reduce conduction losses, while its gate charge and switching characteristics need to be considered when operating at higher frequencies.

Battery-Powered Equipment

The IRFZ44N can be used for switching and load-control functions in battery-powered equipment where the battery voltage and transient conditions remain within the MOSFET's ratings.

Load Switching

The MOSFET can also function as an electronic switch for high-current DC loads. Depending on the circuit configuration, it can be used for power distribution, load disconnect and other controlled switching functions.

IRFZ44N Design Considerations

The 55 V drain-to-source rating should be evaluated against both the normal supply voltage and transient voltage spikes. Inductive loads can generate voltage transients during turn-off, so appropriate protection should be considered where necessary.

Gate protection is also important. The maximum VGS rating is ±20 V, and exceeding this limit can damage the gate oxide.

Thermal performance is another major design factor. The 49 A maximum continuous drain current is specified under particular thermal conditions and should not be interpreted as a guaranteed operating current for every PCB or enclosure design.

For switching applications, designers should also consider gate-driver strength, switching frequency, gate resistance, PCB layout, parasitic inductance and electromagnetic interference.

IRFZ44N Sourcing Considerations

The exact manufacturer part number should be confirmed when sourcing IRFZ44N. Infineon currently lists IRFZ44N as an active product in a TO-220 package and identifies the ordering part number IRFZ44NPBF.

Buyers should distinguish IRFZ44N from related devices with similar names, including IRFZ44NS and other members of the IR MOSFET family. IRFZ44NS, for example, uses a D²PAK package rather than the TO-220 package associated with IRFZ44N.

For production purchasing, the complete ordering code, package, quantity, product condition and delivery requirements should be confirmed before an order is placed.

IRFZ44N for Electronic Component Procurement

IRFZ44N is a 55 V N-channel power MOSFET designed for high-current switching applications. Its 49 A continuous drain current rating, 17.5 mΩ maximum RDS(on) at the specified gate-drive condition and TO-220 package make it relevant to motor control, power conversion, inverters, load switching and battery-powered equipment.

When selecting IRFZ44N, engineers should evaluate voltage margin, load current, gate-drive voltage, conduction losses, switching losses and thermal conditions together. Buyers should also verify the exact package and ordering code when comparing available electronic component suppliers.