IRF634 N-Channel MOSFET 250V 8.1A Equivalent & Substitute Parts

Part Overview

The IRF634 is an N-Channel Metal Oxide Semiconductor Field Effect Transistor (MOSFET) rated for 250V drain-to-source voltage with 8.1A continuous drain current at 25°C. The device is packaged in a TO-220AB through-hole configuration and dissipates up to 74W at the case temperature. The IRF634 is classified as obsolete, making identification of active equivalent and substitute parts essential for ongoing design support, production continuity, and component procurement.

Substiute Parts

IRF634

Vishay SiliconixIn Stock: 1345IRF634 Datasheet

Current PartRFQ

IRF634PBF

Vishay SiliconixIn Stock: 38338IRF634PBF Datasheet

DirectRFQ

RCX100N25

Rohm SemiconductorIn Stock: 1623RCX100N25 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the IRF634 is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

• Drain-to-Source Voltage (Vdss): Must equal or exceed 250V
• Continuous Drain Current (Id): Must equal or exceed 8.1A at 25°C
• Gate Drive Voltage: Must support 10V operation
• Gate Threshold Voltage (Vgs(th)): Must be compatible with 4V @ 250µA specification
• Maximum Gate Voltage (Vgs): Must accommodate ±20V or greater
• Operating Temperature Range: Must span -55°C to 150°C (TJ)

Mechanical Compatibility Criteria:

• Mounting Type: Through Hole required
• Package / Case: TO-220-3 or equivalent footprint

Substitute parts are grouped into two categories based on these criteria:

Category 1: Direct Electrical and Mechanical Equivalents Parts that match all electrical parameters and use identical or compatible packaging.

Category 2: Functional Substitutes with Parameter Variations Parts that meet or exceed critical electrical requirements but may have different secondary specifications or packaging variants.

Parameter Comparison

Engineering Selection Recommendations

IRF634PBF (Vishay Siliconix) — Recommended Primary Substitute

The IRF634PBF is the direct active equivalent of the obsolete IRF634. It maintains identical electrical specifications across all critical parameters: 250V Vdss, 8.1A continuous drain current, 450mOhm Rds(on), 41nC gate charge, and -55°C to 150°C operating temperature range. The IRF634PBF is manufactured by the same supplier (Vishay Siliconix) and uses the same TO-220-3 package footprint. The primary distinction is product status: IRF634PBF is active with significantly higher inventory availability (38,261 units) compared to the obsolete IRF634 (1,286 units). IRF634PBF carries ROHS3 compliance, whereas the original IRF634 is RoHS non-compliant. This substitute provides seamless drop-in replacement capability for existing designs without circuit modification.

RCX100N25 (Rohm Semiconductor) — Alternative Substitute with Parameter Variations

The RCX100N25 is a functional substitute that meets the core voltage and current requirements of the IRF634. It provides 250V Vdss and exceeds the continuous drain current specification at 10A (Ta) versus 8.1A (Tc) for the IRF634. The RCX100N25 operates at the same 10V drive voltage and supports a wider maximum gate voltage range (±30V versus ±20V). However, the RCX100N25 exhibits reduced power dissipation capability (40W Tc versus 74W Tc) and uses a TO-220FM package variant (full pack) rather than the standard TO-220AB. Detailed specifications for Rds(on), Vgs(th), gate charge, and input capacitance are not provided for the RCX100N25. This substitute is suitable for applications where the reduced power dissipation rating is acceptable and where the TO-220FM footprint is compatible with the circuit board layout. The RCX100N25 carries ROHS3 compliance and is actively manufactured by Rohm Semiconductor.

Compliance and Regulatory Considerations

Both active substitutes (IRF634PBF and RCX100N25) are ROHS3 compliant and REACH unaffected, addressing modern regulatory requirements. The obsolete IRF634 is RoHS non-compliant, making transition to an active substitute necessary for new production runs or designs subject to RoHS regulations. Both substitutes carry the same ECCN (EAR99) and HTSUS (8541.29.0095) classifications as the original part.

Frequently Asked Questions (FAQ)

Q: Can the IRF634PBF be used as a direct replacement for the IRF634 without circuit modification?

A: Yes. The IRF634PBF is electrically and mechanically identical to the IRF634 across all specified parameters. It uses the same TO-220-3 package and maintains identical Vdss (250V), Id (8.1A), Rds(on) (450mOhm), gate charge (41nC), and operating temperature range (-55°C to 150°C). The IRF634PBF is a direct drop-in substitute requiring no circuit changes.

Q: What are the key differences between the IRF634 and RCX100N25?

A: The RCX100N25 exceeds the IRF634 in continuous drain current (10A versus 8.1A) and maximum gate voltage (±30V versus ±20V). However, the RCX100N25 has reduced power dissipation capability (40W versus 74W) and uses a TO-220FM package variant instead of TO-220AB. Detailed electrical parameters such as Rds(on), Vgs(th), gate charge, and input capacitance are not specified for the RCX100N25. The RCX100N25 is suitable for applications where the lower power dissipation rating is acceptable.

Q: Why is the IRF634 listed as obsolete?

A: The IRF634 is classified as obsolete by the manufacturer, indicating it is no longer in active production. The IRF634PBF has replaced it as the active equivalent. Existing inventory of the IRF634 remains available (1,286 units), but new designs should transition to the IRF634PBF to ensure long-term supply continuity and compliance with current regulatory standards.

Q: Are both substitute parts RoHS compliant?

A: Yes. Both the IRF634PBF and RCX100N25 are ROHS3 compliant. The original IRF634 is RoHS non-compliant. For applications subject to RoHS regulations, either active substitute must be used.

Q: What is the difference between TO-220AB and TO-220FM packaging?

A: Both are through-hole TO-220-3 packages with compatible footprints. TO-220AB is the standard variant used by the IRF634 and IRF634PBF. TO-220FM is a full-pack variant used by the RCX100N25. The mechanical footprint and pin configuration remain compatible, but the full-pack variant may have different lead forming or tape-and-reel specifications. Verify board layout compatibility before substitution.

Q: Can the RCX100N25 be used in high-power dissipation applications designed for the IRF634?

A: No. The RCX100N25 has a maximum power dissipation rating of 40W (Tc) compared to 74W (Tc) for the IRF634. Applications requiring sustained power dissipation above 40W must use the IRF634 or IRF634PBF. The RCX100N25 is suitable only for applications where power dissipation remains below 40W.

Q: What inventory levels are available for each substitute?

A: The IRF634PBF has the highest availability at 38,261 units in stock. The RCX100N25 has 1,548 units available. The obsolete IRF634 has 1,286 units remaining. For new production, the IRF634PBF is the recommended choice due to superior availability and active product status.

Q: Are there any differences in gate drive requirements between the substitutes?

A: All three parts (IRF634, IRF634PBF, and RCX100N25) operate at 10V drive voltage for maximum Rds(on) specification. The RCX100N25 supports a wider maximum gate voltage range (±30V versus ±20V), providing additional design flexibility. Gate threshold voltage and gate charge specifications are identical for the IRF634 and IRF634PBF (4V @ 250µA and 41nC @ 10V, respectively). These parameters are not specified for the RCX100N25.