STP85NF55L N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The STP85NF55L is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 55V drain-to-source voltage and 80A continuous drain current at 25°C. The device is housed in a TO-220-3 package and is part of the STripFET™ II series. This part is classified as obsolete, making equivalent and substitute components necessary for new designs and ongoing production support. Substitute parts must maintain electrical compatibility across voltage, current, and thermal performance parameters while supporting the same through-hole TO-220 mounting configuration.

Key Parameters

Parameter	Value	Unit
Drain to Source Voltage (Vdss)	55	V
Continuous Drain Current (Id) @ 25°C	80	A (Tc)
On-State Resistance (Rds On) @ 40A, 10V	8	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	2.5	V
Gate Charge (Qg) @ 5V	110	nC
Input Capacitance (Ciss) @ 25V	4050	pF
Power Dissipation (Max)	300	W (Tc)
Operating Temperature Range	-55 to 175	°C (TJ)
Package Type	TO-220-3	Through Hole
FET Type	N-Channel	MOSFET

Substitute Part Grouping Explanation

Substitution eligibility for the STP85NF55L is determined by the following critical parameters:

Voltage Rating: All substitute parts must maintain a Vdss rating of 55V or higher to ensure safe operation within the original design envelope.

Current Rating: Substitute parts must support a continuous drain current (Id) of 80A or greater at 25°C to meet or exceed the original performance specification.

On-State Resistance: Rds On values must not exceed the original specification to prevent excessive power dissipation and thermal stress in the circuit.

Package Configuration: All substitutes must use the TO-220-3 through-hole package to ensure mechanical and thermal compatibility with existing PCB layouts and heat sink mounting.

Operating Temperature: All substitutes must support the full -55°C to 175°C operating range.

Compliance: RoHS3 compliance and REACH unaffected status are required for regulatory alignment.

Substitute parts are grouped into two categories: Direct Equivalents (matching or exceeding all key parameters with active product status) and Compatible Alternatives (meeting electrical requirements but with different product status or slightly modified specifications).

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Id @ 25°C (A)	Rds On (mOhm)	Qg (nC)	Ciss (pF)	Pd Max (W)	Package	Status
STP85NF55L	STMicroelectronics	55	80 (Tc)	8 @ 40A, 10V	110 @ 5V	4050 @ 25V	300	TO-220-3	Obsolete
HUF75344P3	onsemi	55	75 (Tc)	8 @ 75A, 10V	210 @ 20V	3200 @ 25V	285	TO-220-3	Active
HUF75345P3	onsemi	55	75 (Tc)	7 @ 75A, 10V	275 @ 20V	4000 @ 25V	325	TO-220-3	Active
HUF75339P3	onsemi	55	75 (Tc)	12 @ 75A, 10V	130 @ 20V	2000 @ 25V	200	TO-220-3	Active
HUF75332P3	onsemi	55	60 (Tc)	19 @ 60A, 10V	85 @ 20V	1300 @ 25V	145	TO-220-3	Active
AUIRF3205Z	Infineon Technologies	55	75 (Tc)	6.5 @ 66A, 10V	110 @ 10V	3450 @ 25V	170	TO-220-3	Not For New Designs
AUIRF3205	International Rectifier	55	75 (Tc)	8 @ 62A, 10V	146 @ 10V	3247 @ 25V	200	TO-220-3	Active
AUIRF3305	Infineon Technologies	55	140 (Tc)	8 @ 75A, 10V	150 @ 10V	3650 @ 25V	330	TO-220-3	Obsolete
IPP80N06S207AKSA1	Infineon Technologies	55	80 (Tc)	6.6 @ 68A, 10V	110 @ 10V	3400 @ 25V	250	TO-220-3	Discontinued at DiGi Electronics
AOT2610L	Alpha & Omega Semiconductor Inc.	60	55 (Tc)	10.7 @ 20A, 10V	30 @ 10V	2007 @ 30V	75	TO-220-3	Active
AOT470	Alpha & Omega Semiconductor Inc.	75	100 (Tc)	10.5 @ 30A, 10V	136 @ 10V	5640 @ 30V	268	TO-220-3	Active

Engineering Selection Recommendations

Primary Substitute (Direct Equivalent): HUF75344P3 (onsemi) is the recommended primary substitute. This device maintains the 55V Vdss rating, delivers 75A continuous drain current, and provides an 8mOhm on-state resistance matching the original specification. The 285W power dissipation rating exceeds the original 300W specification, and the part carries active product status with full RoHS3 compliance. The TO-220-3 package ensures direct mechanical compatibility.

Secondary Substitute (Enhanced Performance): HUF75345P3 (onsemi) offers superior thermal performance with 325W power dissipation and lower on-state resistance (7mOhm), while maintaining 55V/75A ratings. This part is suitable for applications requiring improved thermal margin. Active product status and RoHS3 compliance are confirmed.

Alternative for Current-Limited Applications: HUF75339P3 (onsemi) provides 55V/75A ratings with 200W power dissipation. This part is appropriate for designs where thermal constraints are less critical. Active product status and RoHS3 compliance are confirmed.

High-Current Alternative: AUIRF3305 (Infineon Technologies) supports 140A continuous drain current at 55V, providing significant current margin. However, this part is classified as obsolete and should not be selected for new designs. The 330W power dissipation rating exceeds the original specification.

Exact Current Match: IPP80N06S207AKSA1 (Infineon Technologies) matches the original 80A continuous drain current rating at 55V. However, this part is discontinued at DiGi Electronics and carries limited availability. The 250W power dissipation rating is below the original 300W specification.

Not Recommended: AOT2610L and AOT470 do not meet the 80A current requirement of the original part. AOT2610L delivers only 55A at Tc, and AOT470, while rated for 100A, operates at 75V Vdss, exceeding the original voltage specification and introducing unnecessary design margin consumption.

Frequently Asked Questions (FAQ)

Q: Can HUF75344P3 be used as a direct replacement for STP85NF55L?

A: HUF75344P3 is electrically compatible with STP85NF55L. Both devices operate at 55V Vdss and deliver comparable on-state resistance (8mOhm). The HUF75344P3 is rated for 75A continuous drain current, which is 5A lower than the original 80A specification. For applications operating at or below 75A, this part provides full compatibility. The TO-220-3 package ensures mechanical and thermal interface compatibility with existing designs.

Q: What is the difference between HUF75344P3 and HUF75345P3?

A: Both parts operate at 55V/75A and use the TO-220-3 package. The primary difference is on-state resistance and power dissipation. HUF75345P3 provides lower on-state resistance (7mOhm versus 8mOhm) and higher power dissipation rating (325W versus 285W). HUF75345P3 is the preferred choice for applications requiring improved thermal performance or lower conduction losses.

Q: Why is AUIRF3305 not recommended despite higher current rating?

A: AUIRF3305 is classified as obsolete, making it unsuitable for new designs and subject to supply discontinuation. While the 140A current rating exceeds the original specification, the obsolete status creates long-term supply risk and potential cost volatility. Active alternatives such as HUF75344P3 and HUF75345P3 provide superior product lifecycle support.

Q: Can AOT470 be used as a substitute?

A: AOT470 is not recommended. Although it delivers 100A continuous drain current, the 75V Vdss rating exceeds the original 55V specification. This higher voltage rating does not provide functional benefit and consumes unnecessary design margin. Additionally, the 268W power dissipation is below the original 300W specification. HUF75344P3 or HUF75345P3 are superior alternatives.

Q: What is the significance of the Rds On parameter in substitution?

A: On-state resistance (Rds On) directly determines conduction losses and heat generation in the MOSFET. Lower Rds On values reduce power dissipation and improve efficiency. When selecting a substitute, Rds On must not exceed the original specification to prevent thermal runaway or circuit malfunction. HUF75345P3 (7mOhm) provides superior performance compared to the original 8mOhm specification.

Q: Are all substitute parts RoHS3 compliant?

A: All recommended substitute parts (HUF75344P3, HUF75345P3, HUF75339P3, and AUIRF3205) carry RoHS3 compliance certification. Compliance status is mandatory for applications subject to regulatory requirements. Verify RoHS3 status in component datasheets before final design approval.

Q: What is the impact of gate charge (Qg) differences on circuit design?

A: Gate charge affects the gate drive circuit requirements and switching speed. Higher Qg values require greater gate drive current and energy. The original STP85NF55L specifies 110nC @ 5V. Substitute parts show varying Qg values (ranging from 30nC to 275nC depending on measurement conditions). Verify gate drive circuit compatibility with the selected substitute part's Qg specification before implementation.

Q: Can IPP80N06S207AKSA1 be used despite discontinued status?

A: IPP80N06S207AKSA1 matches the original 80A current rating and 55V voltage specification. However, the part is discontinued at DiGi Electronics, indicating limited availability and potential supply chain risk. The 250W power dissipation rating is also below the original 300W specification. Active alternatives such as HUF75344P3 provide superior long-term availability and thermal performance.

Q: What package considerations apply to these substitutes?

A: All recommended substitute parts use the TO-220-3 through-hole package, ensuring direct mechanical compatibility with existing PCB layouts and heat sink mounting hardware. No package adapter or redesign is required. Verify PCB pad dimensions and heat sink mounting hole spacing match TO-220-3 specifications before component procurement.

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