IRF840 N-Channel MOSFET 500V 8A Equivalent & Substitute Parts

Part Overview

The IRF840 is an N-Channel Metal Oxide Semiconductor Field Effect Transistor (MOSFET) rated for 500V drain-to-source voltage and 8A continuous drain current in a Through Hole TO-220 package. Manufactured by STMicroelectronics as part of the PowerMESH™ II series, this device is classified as obsolete product status. Due to its obsolete designation, equivalent and substitute parts from active product lines are necessary for new designs and ongoing production requirements. Substitute devices maintain electrical compatibility while offering improved availability and compliance certifications.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain to Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	8	A
On-State Resistance (Rds On Max) @ Id, Vgs	850 mOhm @ 3.5A, 10V	—
Gate Threshold Voltage (Vgs(th) Max) @ Id	4	V @ 250µA
Power Dissipation (Max)	125	W (Tc)
Mounting Type	Through Hole	—
Package / Case	TO-220-3	—
Operating Temperature Range	150	°C (TJ Max)

Substitute Part Grouping Explanation

Substitution of the IRF840 is determined by strict equivalence across the following critical electrical and mechanical parameters:

Electrical Equivalence Criteria:

Drain to Source Voltage (Vdss): 500V minimum
Continuous Drain Current (Id): 8A or greater at 25°C
On-State Resistance (Rds On): 850 mOhm or lower at specified gate voltage
Gate Threshold Voltage (Vgs(th)): 4V or lower
Power Dissipation: 125W or greater

Mechanical Equivalence Criteria:

Mounting Type: Through Hole or Surface Mount (package-dependent)
Package Family: TO-220 series or equivalent footprint compatibility
Pin Configuration: TO-220-3 standard

Substitute parts are grouped into two categories:

Category 1: Direct Through-Hole TO-220 Equivalents Parts maintaining identical Through Hole TO-220 mounting and electrical specifications. These include IRF840APBF, IRF840LCPBF, and IRF840PBF from Vishay Siliconix, all rated for 500V/8A with 125W power dissipation.

Category 2: Enhanced Performance Alternatives The AOT9N50 from Alpha & Omega Semiconductor Inc. provides increased continuous drain current (9A) and power dissipation (192W) while maintaining 500V voltage rating and TO-220 mounting, suitable for applications requiring higher current capacity.

Category 3: Surface Mount Alternative The IRF840LPBF offers identical electrical specifications in a Surface Mount TO-263 (D2PAK) package for applications requiring surface mount technology.

Parameter Comparison

Parameter	IRF840 (Main)	IRF840APBF	IRF840LCPBF	IRF840PBF	IRF840LPBF	AOT9N50
Manufacturer	STMicroelectronics	Vishay Siliconix	Vishay Siliconix	Vishay Siliconix	Vishay Siliconix	Alpha & Omega Semiconductor Inc.
Vdss (V)	500	500	500	500	500	500
Id @ 25°C (A)	8	8	8	8	8	9
Rds On Max (mOhm)	850 @ 3.5A, 10V	850 @ 4.8A, 10V	850 @ 4.8A, 10V	850 @ 4.8A, 10V	850 @ 4.8A, 10V	850 @ 4.5A, 10V
Vgs(th) Max (V)	4 @ 250µA	4 @ 250µA	4 @ 250µA	4 @ 250µA	4 @ 250µA	4.5 @ 250µA
Gate Charge Qg Max (nC)	39 @ 10V	38 @ 10V	39 @ 10V	63 @ 10V	63 @ 10V	28 @ 10V
Power Dissipation Max (W)	125	125	125	125	125	192
Operating Temperature (°C)	150 (TJ Max)	-55 to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Surface Mount	Through Hole
Package	TO-220-3	TO-220AB	TO-220AB	TO-220AB	TO-263-3 (D2PAK)	TO-220-3
Product Status	Obsolete	Active	Active	Active	Active	Not For New Designs
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement in Through-Hole Applications:

IRF840APBF, IRF840LCPBF, and IRF840PBF are functionally equivalent substitutes for the obsolete IRF840. All three are manufactured by Vishay Siliconix with Active product status, ensuring long-term availability and supply chain reliability. These devices maintain identical electrical specifications (500V/8A/125W) and TO-220 Through Hole packaging. All three variants are ROHS3 compliant, addressing regulatory requirements that the original IRF840 does not meet.

IRF840PBF offers the highest inventory availability (329,719 pieces) and is recommended as the primary replacement for volume production. IRF840LCPBF provides the second-highest availability (23,636 pieces) with identical electrical performance. IRF840APBF is suitable for applications where REACH compliance is required, as it is REACH Affected (indicating full regulatory documentation).

For Surface Mount Applications:

IRF840LPBF provides equivalent electrical performance in a Surface Mount TO-263 (D2PAK) package. This variant is appropriate for PCB designs requiring surface mount technology while maintaining the same 500V/8A/125W specifications. ROHS3 compliance is confirmed.

For Enhanced Current Capacity:

AOT9N50 from Alpha & Omega Semiconductor Inc. offers increased continuous drain current (9A) and power dissipation (192W) in a Through Hole TO-220 package. This device is suitable for applications requiring higher thermal headroom or current margins. However, AOT9N50 carries "Not For New Designs" status, limiting its use to legacy system maintenance or applications where the enhanced specifications provide specific design advantages.

Compliance Considerations:

The original IRF840 is RoHS non-compliant. All recommended substitutes (IRF840APBF, IRF840LCPBF, IRF840PBF, IRF840LPBF) are ROHS3 compliant. For applications subject to RoHS regulations, these substitutes are mandatory.

Frequently Asked Questions (FAQ)

Q: Can IRF840APBF, IRF840LCPBF, and IRF840PBF be used interchangeably with the original IRF840?

A: Yes. All three Vishay Siliconix variants maintain identical electrical specifications (500V Vdss, 8A Id, 125W power dissipation, 850 mOhm Rds On) and TO-220-3 package configuration. Pin-to-pin compatibility is confirmed. The primary differences are product status (all Active versus Obsolete) and compliance certifications (all ROHS3 compliant).

Q: What is the difference between IRF840APBF, IRF840LCPBF, and IRF840PBF?

A: All three devices are electrically equivalent with identical voltage, current, and power ratings. Differences include gate charge specifications (IRF840APBF and IRF840LCPBF: 38-39 nC; IRF840PBF: 63 nC) and input capacitance values. IRF840PBF has significantly higher inventory availability. Selection should be based on supply chain requirements and specific gate drive circuit characteristics.

Q: Is IRF840LPBF a direct replacement for the original IRF840?

A: IRF840LPBF is electrically equivalent but differs in mounting technology. The original IRF840 uses Through Hole TO-220 mounting, while IRF840LPBF uses Surface Mount TO-263 (D2PAK) packaging. IRF840LPBF is suitable only for PCB designs that accommodate surface mount components. Through Hole applications require IRF840APBF, IRF840LCPBF, or IRF840PBF.

Q: Should AOT9N50 be used as a replacement for the IRF840?

A: AOT9N50 is electrically compatible (500V Vdss, 9A Id, 192W power dissipation) and maintains Through Hole TO-220 mounting. However, AOT9N50 carries "Not For New Designs" product status. It is suitable for legacy system maintenance or applications where the increased current capacity (9A versus 8A) and power dissipation (192W versus 125W) provide specific design advantages. For new designs, IRF840APBF, IRF840LCPBF, or IRF840PBF are preferred.

Q: Are there package compatibility concerns when substituting the IRF840?

A: Package compatibility depends on the specific substitute selected. IRF840APBF, IRF840LCPBF, and IRF840PBF maintain Through Hole TO-220-3 packaging identical to the original IRF840, ensuring direct PCB compatibility. IRF840LPBF uses Surface Mount TO-263 (D2PAK) packaging and requires PCB redesign. AOT9N50 uses Through Hole TO-220-3 packaging compatible with the original footprint.

Q: What compliance certifications should be verified when selecting a substitute?

A: The original IRF840 is RoHS non-compliant. All recommended substitutes are ROHS3 compliant. For applications subject to RoHS regulations (EU Directive 2011/65/EU and amendments), ROHS3 compliance is mandatory. IRF840APBF is REACH Affected, indicating full REACH compliance documentation. IRF840LCPBF is REACH Unaffected. IRF840PBF is REACH Affected. Verify REACH requirements based on application geography and regulatory jurisdiction.

Q: What is the significance of "Active" versus "Not For New Designs" product status?

A: "Active" status indicates the manufacturer actively produces and supports the device with full technical documentation and long-term availability commitment. "Not For New Designs" status indicates the manufacturer no longer recommends the device for new applications, though existing inventory may be available. For production designs, Active status devices (IRF840APBF, IRF840LCPBF, IRF840PBF, IRF840LPBF) are preferred over AOT9N50.

Q: How do gate charge differences between substitute parts affect circuit design?

A: Gate charge (Qg) affects gate drive circuit design and switching speed. The original IRF840 specifies 39 nC @ 10V. IRF840APBF and IRF840LCPBF maintain similar gate charge (38-39 nC). IRF840PBF and IRF840LPBF specify higher gate charge (63 nC), requiring higher gate drive current for equivalent switching speed. AOT9N50 specifies lower gate charge (28 nC), enabling faster switching with reduced gate drive requirements. Gate drive circuit compatibility should be verified based on the selected substitute.

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