IRF840LC N-Channel MOSFET 500V 8A Equivalent & Substitute Parts

Part Overview

The IRF840LC is an N-Channel MOSFET manufactured by Vishay Siliconix, rated for 500V drain-to-source voltage with 8A continuous drain current at 25°C. This device is housed in a TO-220AB through-hole package and is designed for high-voltage switching applications requiring 125W maximum power dissipation. The part maintains active product status and is currently in stock with 4450 units available.

Equivalent and substitute parts are identified based on matching electrical specifications and mechanical compatibility. Substitutes are selected when they satisfy the core operating parameters: drain-to-source voltage rating, continuous drain current, on-state resistance, gate threshold voltage, and through-hole TO-220 package configuration.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain to Source Voltage (Vdss)	500	V
Current - Continuous Drain (Id) @ 25°C	8	A (Tc)
Rds On (Max) @ Id, Vgs	850 mOhm @ 4.8A, 10V	—
Vgs(th) (Max) @ Id	4	V @ 250µA
Power Dissipation (Max)	125	W (Tc)
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-220-3	—

Substitute Part Grouping Explanation

Substitution logic for the IRF840LC is based on the following critical parameters that must be matched or exceeded:

Electrical Compatibility Criteria:

Drain-to-source voltage (Vdss) must equal or exceed 500V
Continuous drain current (Id) must equal or exceed 8A at 25°C
On-state resistance (Rds On) must not exceed 850 mOhm at the specified gate-source voltage
Gate threshold voltage (Vgs(th)) must be compatible with 10V drive voltage
Power dissipation capability must support the application thermal requirements

Mechanical Compatibility Criteria:

Mounting type: Through Hole
Package configuration: TO-220-3 (TO-220AB or TO-220 variant)

Compliance Considerations:

Product status must be Active
RoHS compliance status is noted for regulatory requirements

Substitute parts are grouped into two categories: direct equivalents (identical electrical and mechanical specifications) and manufacturer-recommended alternatives (equivalent performance with minor parameter variations within acceptable engineering tolerances).

Parameter Comparison

Parameter	IRF840LC	IRF840LCPBF	STP9NK50Z
Manufacturer	Vishay Siliconix	Vishay Siliconix	STMicroelectronics
FET Type	N-Channel	N-Channel	N-Channel
Vdss (V)	500	500	500
Id @ 25°C (A)	8	8	7.2
Rds On (Max) @ Vgs 10V (mOhm)	850 @ 4.8A	850 @ 4.8A	850 @ 3.6A
Vgs(th) (Max) (V)	4 @ 250µA	4 @ 250µA	4.5 @ 100µA
Gate Charge Qg (Max) @ 10V (nC)	39	39	32
Input Capacitance Ciss (Max) @ 25V (pF)	1100	1100	910
Power Dissipation (Max) (W)	125	125	110
Operating Temperature Range (°C)	-55 to 150	-55 to 150	-55 to 150
Package / Case	TO-220-3	TO-220-3	TO-220-3
Mounting Type	Through Hole	Through Hole	Through Hole
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant
Inventory (Pcs)	4450	23636	15942

Engineering Selection Recommendations

IRF840LCPBF (Vishay Siliconix)

The IRF840LCPBF is a direct electrical and mechanical equivalent to the IRF840LC. Both parts share identical electrical specifications: 500V Vdss, 8A continuous drain current, 850 mOhm Rds On, and 125W power dissipation. The primary distinction is packaging format (tube versus bulk) and RoHS compliance status. The IRF840LCPBF is ROHS3 compliant, whereas the IRF840LC is non-compliant. This substitute is suitable for applications requiring RoHS-compliant components or when tube packaging is preferred. Inventory availability is significantly higher at 23636 units.

STP9NK50Z (STMicroelectronics)

The STP9NK50Z is a manufacturer-recommended alternative from STMicroelectronics, rated for 500V Vdss with 7.2A continuous drain current. This part exhibits lower gate charge (32 nC versus 39 nC) and reduced input capacitance (910 pF versus 1100 pF), resulting in faster switching characteristics. The on-state resistance remains equivalent at 850 mOhm, though measured at a lower current level (3.6A versus 4.8A). Power dissipation is rated at 110W compared to 125W for the IRF840LC. The STP9NK50Z is ROHS3 compliant and features SuperMESH™ technology. This substitute is appropriate for applications where the 7.2A current rating is sufficient and where improved switching performance is beneficial. The lower power dissipation rating requires thermal design verification for high-power applications.

Both substitute parts maintain the same operating temperature range (-55°C to 150°C) and through-hole TO-220-3 package configuration, ensuring mechanical compatibility with existing PCB layouts.

Frequently Asked Questions (FAQ)

Q: Can IRF840LCPBF be used as a direct replacement for IRF840LC?

A: Yes. The IRF840LCPBF is electrically and mechanically identical to the IRF840LC. Both parts are manufactured by Vishay Siliconix and share all critical electrical parameters: 500V Vdss, 8A Id, 850 mOhm Rds On, and 125W power dissipation. The difference is packaging format (tube) and RoHS compliance status (ROHS3 compliant). No circuit modifications are required.

Q: Is the STP9NK50Z a suitable substitute for the IRF840LC?

A: The STP9NK50Z is suitable for applications where the 7.2A continuous drain current rating meets or exceeds the design requirement. The part maintains 500V Vdss and 850 mOhm Rds On specifications. However, the power dissipation rating is lower (110W versus 125W), requiring thermal design verification. The lower gate charge and input capacitance provide faster switching performance. Applications requiring the full 8A rating should not use this substitute.

Q: What is the difference between the IRF840LC and IRF840LCPBF packaging?

A: The IRF840LC is supplied in bulk packaging, while the IRF840LCPBF is supplied in tube packaging. Both use the same TO-220AB through-hole package configuration. Tube packaging provides better component protection during handling and storage. The choice between bulk and tube depends on assembly process requirements and inventory management practices.

Q: Are all three parts RoHS compliant?

A: No. The IRF840LC is RoHS non-compliant. Both the IRF840LCPBF and STP9NK50Z are ROHS3 compliant. Applications subject to RoHS regulations must use either the IRF840LCPBF or STP9NK50Z.

Q: Can the STP9NK50Z handle the same power dissipation as the IRF840LC?

A: The STP9NK50Z is rated for 110W maximum power dissipation, compared to 125W for the IRF840LC. Applications requiring sustained power dissipation above 110W should use the IRF840LC or IRF840LCPBF. Thermal design analysis is required to confirm the STP9NK50Z is suitable for applications operating near its power dissipation limit.

Q: What are the switching performance differences between these parts?

A: The STP9NK50Z exhibits lower gate charge (32 nC versus 39 nC) and reduced input capacitance (910 pF versus 1100 pF) compared to the IRF840LC and IRF840LCPBF. These characteristics result in faster switching transitions and reduced gate drive power requirements. The IRF840LC and IRF840LCPBF are electrically identical in switching performance.

Q: Are these parts pin-compatible?

A: Yes. All three parts use the TO-220-3 package configuration with identical pin assignments: Gate, Drain, and Source. No PCB layout modifications are required when substituting between these parts.

Q: Which substitute should be selected for new designs?

A: For new designs, the IRF840LCPBF is recommended as it provides identical electrical performance to the IRF840LC with ROHS3 compliance and higher inventory availability. The STP9NK50Z is recommended when improved switching performance and lower gate charge are beneficial, provided the 7.2A current rating and 110W power dissipation are acceptable for the application.

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