STP8NM50 N-Channel MOSFET 550V 8A Equivalent & Substitute Parts

Part Overview

The STP8NM50 is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 550V drain-to-source voltage with 8A continuous drain current at 25°C. This device is packaged in TO-220-3 through-hole configuration and is part of the MDmesh™ II series. The STP8NM50 is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and component procurement.

Substitute parts must maintain functional compatibility across critical electrical parameters including voltage rating, current capacity, on-resistance characteristics, and thermal performance while accommodating packaging and compliance variations.

Key Parameters

Parameter	STP8NM50	Unit
FET Type	N-Channel	—
Technology	MOSFET (Metal Oxide)	—
Drain to Source Voltage (Vdss)	550	V
Current - Continuous Drain (Id) @ 25°C	8	A (Tc)
Drive Voltage (Max Rds On)	10	V
Rds On (Max) @ Id, Vgs	800	mOhm @ 2.5A, 10V
Vgs(th) (Max) @ Id	5	V @ 250µA
Gate Charge (Qg) (Max) @ Vgs	13	nC @ 10V
Vgs (Max)	±30	V
Input Capacitance (Ciss) (Max) @ Vds	415	pF @ 25V
Power Dissipation (Max)	100	W (Tc)
Operating Temperature	-65 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-220-3	—
Product Status	Obsolete	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the STP8NM50 is determined by the following critical electrical parameters:

Voltage Rating Compatibility: Substitute parts must maintain a Vdss rating equal to or greater than 550V to ensure safe operation in the original circuit topology. Parts with lower voltage ratings are not suitable.

Current Capacity: Substitute parts must support continuous drain current (Id) at 25°C equal to or greater than 8A to meet or exceed the original device performance.

On-Resistance (Rds On): The on-resistance at specified gate-source voltage and drain current must be comparable to ensure thermal performance and power dissipation remain within acceptable limits.

Gate Charge and Input Capacitance: These parameters affect switching speed and gate drive requirements. Substitute parts with significantly different values may require circuit redesign.

Packaging and Mounting: The TO-220-3 through-hole package is the primary form factor. Substitutes in alternative packages (TO-262-3) are listed but require PCB layout modifications.

Compliance and Product Status: Active product status and RoHS3 compliance are preferred for new designs and long-term availability.

Based on these criteria, the substitute parts are grouped as follows:

Group 1 - Direct TO-220 Substitutes (Voltage ≥ 500V, Current ≥ 8A): AOT9N50, IRFB11N50APBF

Group 2 - Lower Current TO-220 Substitutes (Voltage ≥ 500V, Current < 8A): IRF830A, IRF830APBF, IRF830PBF

Group 3 - Alternative Package Substitutes (TO-262-3): IRF830LPBF

Parameter Comparison

Parameter	STP8NM50	AOT9N50	IRF830A	IRF830APBF	IRF830LPBF	IRF830PBF	IRFB11N50APBF	Unit
Vdss	550	500	500	500	500	500	500	V
Id @ 25°C	8	9	5	5	4.5	4.5	11	A (Tc)
Rds On (Max) @ 10V	800 mOhm @ 2.5A	850 mOhm @ 4.5A	1.4 Ohm @ 3A	1.4 Ohm @ 3A	1.5 Ohm @ 2.7A	1.5 Ohm @ 2.7A	520 mOhm @ 6.6A	—
Vgs(th) (Max) @ 250µA	5	4.5	4.5	4.5	4	4	4	V
Gate Charge (Qg) @ 10V	13	28	24	24	38	38	52	nC
Ciss (Max) @ 25V	415	1042	620	620	610	610	1423	pF
Power Dissipation (Max)	100	192	74	74	74	74	170	W (Tc)
Operating Temperature	-65 to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150	°C (TJ)
Package / Case	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-262-3	TO-220-3	TO-220-3	—
Product Status	Obsolete	Not For New Designs	Active	Active	Active	Active	Active	—
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

For Direct Replacement (TO-220-3 Package, Vdss ≥ 500V, Id ≥ 8A):

The IRFB11N50APBF is the primary substitute for the STP8NM50. This device exceeds the original current rating at 11A continuous drain current, maintains 500V voltage rating, and is classified as Active with ROHS3 compliance. The lower on-resistance (520 mOhm @ 6.6A) provides improved thermal performance compared to the original 800 mOhm specification.

The AOT9N50 provides an alternative with 9A current capacity and comparable on-resistance (850 mOhm @ 4.5A). However, this part is classified as Not For New Designs, limiting its suitability for long-term applications.

For Current-Limited Applications (TO-220-3 Package, Vdss ≥ 500V, Id < 8A):

The IRF830APBF and IRF830PBF are suitable substitutes where circuit design accommodates reduced current capacity (5A and 4.5A respectively). Both devices are Active with ROHS3 compliance. The IRF830APBF is preferred due to REACH Affected status indicating current regulatory tracking, while IRF830PBF offers the largest inventory availability (25,300 units).

The IRF830A provides equivalent electrical performance to IRF830APBF but is classified as RoHS non-compliant, limiting use in regulated applications.

For Alternative Packaging (TO-262-3):

The IRF830LPBF accommodates applications requiring the TO-262-3 long-lead package. This substitution requires PCB layout modification and is suitable only where package form factor is a design requirement. Current capacity is reduced to 4.5A.

Compliance Considerations:

All recommended substitutes maintain ROHS3 compliance except IRF830A. For applications subject to REACH regulations, IRFB11N50APBF is classified as REACH Unaffected, while IRF830APBF and IRF830PBF are REACH Affected. Verify regulatory requirements before final component selection.

Frequently Asked Questions (FAQ)

Q: Can the AOT9N50 directly replace the STP8NM50 in all applications?

A: The AOT9N50 meets the minimum voltage (500V) and current (9A) requirements for direct substitution in TO-220-3 packaging. However, the part is classified as Not For New Designs, indicating limited long-term availability and support. For new designs, IRFB11N50APBF is the preferred substitute.

Q: What is the impact of lower Vdss rating (500V vs. 550V) in substitute parts?

A: Substitute parts rated at 500V Vdss are suitable for circuits designed for the original 550V device, as they operate within the original voltage envelope. However, they provide reduced voltage margin. Verify circuit maximum voltage stress does not exceed 500V under all operating conditions, including transient overvoltage events.

Q: Why do substitute parts show higher on-resistance values?

A: The IRF830 series devices (IRF830A, IRF830APBF, IRF830PBF) exhibit higher on-resistance (1.4 to 1.5 Ohm) compared to the STP8NM50 (800 mOhm) due to lower current ratings. These parts are suitable only for applications where the 8A current requirement can be reduced. The IRFB11N50APBF provides lower on-resistance (520 mOhm) and is preferred for high-current applications.

Q: Can I use IRF830LPBF as a substitute if I modify the PCB layout?

A: Yes, the IRF830LPBF is electrically compatible but requires PCB layout modification due to TO-262-3 packaging (long leads) versus the original TO-220-3. Current capacity is reduced to 4.5A. This substitution is justified only when the alternative package form factor provides design benefits.

Q: What is the significance of Gate Charge (Qg) differences between parts?

A: Gate charge affects switching speed and gate drive circuit requirements. The STP8NM50 has 13 nC gate charge, while substitutes range from 24 to 52 nC. Higher gate charge requires longer switching times and may increase switching losses. Verify gate drive circuit can supply sufficient current for the substitute part's gate charge specification.

Q: Are there inventory or lead-time considerations for substitute selection?

A: Yes. IRF830PBF has the largest inventory (25,300 units), followed by IRFB11N50APBF (15,426 units). AOT9N50 has 3,846 units available. For applications requiring immediate availability, IRF830PBF is the preferred choice despite lower current rating.

Q: What is the difference between IRF830A and IRF830APBF?

A: Both devices have identical electrical specifications (500V, 5A, 1.4 Ohm Rds On). The primary difference is packaging: IRF830A is supplied in standard packaging, while IRF830APBF is supplied in tube packaging. IRF830APBF is ROHS3 compliant, while IRF830A is RoHS non-compliant. For regulated applications, IRF830APBF is required.

Q: Can I use IRFB11N50APBF in a circuit designed for lower current?

A: Yes. The IRFB11N50APBF is rated for 11A continuous drain current, exceeding the original 8A specification. It can be used in any application designed for 8A or lower current. The superior on-resistance (520 mOhm) provides improved thermal performance and reduced power dissipation compared to the original device.

Q: What operating temperature range should I verify for substitute parts?

A: The STP8NM50 operates from -65°C to 150°C (TJ). All substitute parts operate from -55°C to 150°C (TJ), providing a reduced low-temperature range of 10°C. Verify circuit minimum operating temperature does not fall below -55°C. For applications requiring -65°C operation, the STP8NM50 is the only suitable device.

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