Vishay Siliconix IRFZ40

Overview

IRFZ40 from Vishay Siliconix is a 60 V, 50 A N-channel enhancement-mode power MOSFET in TO-220AB package, featuring 0.028 Ω R_DS(on) at V_GS = 10 V, 67 nC total gate charge, and 175 °C maximum junction temperature. It delivers fast switching, rugged avalanche capability (100 mJ), and ease of paralleling for high-current DC-DC converters, motor drives, and SMPS primary-side switches.

For engineers reviewing the IRFZ40 datasheet, IRFZ40 pinout, IRFZ40 application, or IRFZ40 equivalent, key selection criteria include its 60 V V_DS, 50 A continuous drain rating at 25 °C, low thermal resistance (R_thJC = 1.0 °C/W), body diode recovery time (120–180 ns), and RoHS-compliant lead-free/halogen-free variant IRFZ40PbF-BE3.

Technical Context

The IRFZ40 employs a third-generation silicon process optimized for low conduction loss and dynamic performance. Its gate threshold voltage (2.0–4.0 V) enables standard 10 V logic-level drive, while the 1900 pF input capacitance and 170 pF reverse transfer capacitance support predictable turn-on/turn-off timing with 14 ns delay and 110 ns rise time under defined test conditions.

Designed for hard-switched topologies, it sustains unclamped inductive switching up to 51 A with 100 mJ single-pulse avalanche energy and exhibits controlled diode recovery (Q_rr = 0.53–0.80 nC, t_rr = 120–180 ns), minimizing voltage overshoot during commutation in flyback and buck converters.

Key Specifications

Pinout & Package

IRFZ40 is housed in a through-hole TO-220AB package with isolated tab (drain-connected), standard mounting hole, and 1.0 °C/W junction-to-case thermal resistance. The case is electrically connected to the drain terminal.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar N-channel power MOSFET applications.

Compared with STP60NF06 and IRFZ44N, the IRFZ40 offers balanced trade-offs: lower gate charge than STP60NF06 for faster switching, and tighter V_GS(th) distribution (2.0–4.0 V) than IRFZ44N for more predictable turn-on in multi-device arrays.

Availability

IRFZ40 is available at Aetrix Electronics and suitable for brushed motor drives, DC-DC buck converters, and inductive load switching requiring stable component supply and long-term industrial lifecycle support.

Supply support for IRFZ40 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Vishay Siliconix is a global leader in discrete semiconductors, specializing in power MOSFETs, diodes, and optoelectronics with emphasis on reliability, ruggedness, and thermal performance.

The IRFZ40 belongs to Vishay's third-generation power MOSFET family, engineered for cost-effective, high-current switching in commercial and industrial power conversion where robustness and ease of use are critical.

FAQ

What is the maximum continuous drain current rating for IRFZ40 at 100 °C case temperature?

The IRFZ40 supports 36 A continuous drain current at T_C = 100 °C, derated linearly from 50 A at 25 °C using a 1.0 W/°C factor. This reflects real-world thermal constraints in enclosed power supplies or motor controllers where heatsink temperature exceeds ambient. The IRFZ40 maintains safe operation up to 175 °C junction temperature, making it suitable for high-temperature industrial deployments.

Does IRFZ40 require a gate resistor for reliable switching in a 100 kHz SMPS application?

Yes - a gate resistor is required to control dI/dt and suppress ringing caused by the IRFZ40's 7.5 nH internal source inductance and PCB layout parasitics. Typical values range from 5 Ω to 25 Ω depending on driver strength and EMI targets. The IRFZ40's 18 nC Q_gs and 25 nC Q_gd define the Miller plateau duration, and improper gate resistance can cause shoot-through or excessive switching loss. Verified layouts use <10 cm gate traces and local 100 nF decoupling near the IRFZ40 source.

Can IRFZ40 be used in parallel configurations without current-sharing resistors?

Yes - the IRFZ40's positive R_DS(on) temperature coefficient (0.060 V/°C) enables inherent thermal current balancing when multiple devices share a common heatsink. As individual die temperatures rise under load, their on-resistance increases, redistributing current toward cooler units. Successful parallel operation of IRFZ40 devices requires matched gate drive paths, symmetrical PCB layout, and mechanical mounting that ensures uniform thermal coupling - no external source resistors are needed for basic current sharing.

What is the body diode reverse recovery charge (Q_rr) of IRFZ40, and why does it matter in synchronous rectification?

The IRFZ40 body diode exhibits Q_rr = 0.53–0.80 nC at T_J = 25 °C, IF = 51 A, and dI/dt = 100 A/μs. In synchronous rectification, this stored charge causes temporary reverse conduction and voltage spikes during turn-off, increasing switching loss and EMI. For the IRFZ40, low Q_rr enables cleaner commutation in buck-derived topologies, especially when paired with precise gate timing to minimize dead-time overlap. Designers must account for this value when selecting gate drivers and calculating snubber sizing.

Is IRFZ40PbF-BE3 pin-compatible with legacy IRFZ40 versions?

Yes - the IRFZ40PbF-BE3 is a direct form-fit-function replacement for all prior IRFZ40 variants, including Pb-bearing versions. It retains identical TO-220AB mechanical dimensions, pinout (G-D-S), thermal characteristics (R_thJC = 1.0 °C/W), and electrical specifications. The "BE3" suffix denotes Vishay's halogen-free and lead-free construction per JEDEC J-STD-609, with no performance or reliability trade-offs. The IRFZ40PbF-BE3 meets RoHS Directive 2011/65/EU and is qualified for industrial temperature range operation.