IRFY440

Now an end-of-life discrete MOSFET from Infineon’s high-reliability portfolio, the IRFY440 is a 500V N-channel power transistor housed in a hermetic TO-257AA package. Infineon has officially discontinued production of this device, making it available exclusively through legacy supply channels. As a result, procurement depends on distributors such as ZZX Electronics that maintain sustaining inventories with full date-code traceability. Designed for rugged duty, the IRFY440 leverages planar DMOS technology to deliver a 500V breakdown voltage, low on-resistance, and strong avalanche capability—characteristics that suit it for high-voltage switching and linear-mode operation in tightly packaged, thermally demanding assemblies. Typical application domains include power supply converters, motor drive bridges, and power distribution control within defense avionics, satellite bus subsystems, and industrial drives where the TO-257AA’s isolated metal base facilitates heat sinking and electrical separation.

For engineering teams managing long-fielded platforms, the IRFY440 provides a direct drop-in path to sustain existing circuits without triggering a board redesign, new-component qualification, or system recertification. ZZX Electronics handles this obsolete part as legacy stock, rigorously enforcing lot-level date-code tracking and incoming inspection to meet counterfeit avoidance protocols. The hermetic package and established radiation-tolerant pedigree make the device relevant for maintaining aerospace and defense equipment, heavy industrial motor controls, and high-reliability power stages already qualified around its electrical and thermal footprint. In these contexts, securing authentic, traceable inventory of the discontinued IRFY440 preserves service continuity and avoids the cost and schedule impact of requalifying an alternative active-sourcing power MOSFET.