IRF3708 N-Channel 30V 62A MOSFET Equivalent & Substitute Parts

Part Overview

The IRF3708 is an N-Channel MOSFET manufactured by Infineon Technologies, rated for 30V drain-to-source voltage with 62A continuous drain current at 25°C. This device features a TO-220AB through-hole package and is part of the HEXFET® series. The IRF3708 is classified as obsolete, making identification of functionally equivalent substitute parts essential for ongoing design support and production continuity. Substitute parts must maintain compatibility across voltage ratings, current handling capacity, thermal characteristics, and package form factor to ensure direct replacement capability in existing circuit designs.

Key Parameters

Parameter	Value	Unit	Specification Condition
Drain-to-Source Voltage (Vdss)	30	V	Maximum rating
Continuous Drain Current (Id)	62	A	@ 25°C (Tc)
On-State Resistance (Rds On)	12	mOhm	@ 15A, 10V Vgs
Gate Threshold Voltage (Vgs(th))	2	V	@ 250µA
Gate Charge (Qg)	24	nC	@ 4.5V Vgs
Power Dissipation	87	W	@ Tc
Operating Temperature Range	-55 to 175	°C	Junction temperature (TJ)
Package Type	TO-220-3	—	Through-hole

Substitute Part Grouping Explanation

Substitute parts for the IRF3708 are grouped based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Critical Matching Parameters:

Drain-to-Source Voltage (Vdss): Must equal or exceed 30V
Package Type: Must be TO-220-3 through-hole configuration
FET Type: N-Channel MOSFET technology
Operating Temperature Range: Must support -55°C to 175°C

Performance Consideration Parameters:

Continuous Drain Current (Id): Determines current-handling capability
On-State Resistance (Rds On): Affects power dissipation and efficiency
Gate Charge (Qg): Influences switching speed and drive requirements
Power Dissipation Rating: Thermal management capability

Substitutes are classified into two categories:

Category A - Direct Current Rating Match (62A): IRLB8721PBF maintains the 62A continuous drain current specification, providing equivalent current-handling performance with improved on-state resistance characteristics and active product status.

Category B - Higher Current Capacity (100A): PSMN4R3-30PL,127 and PSMN2R0-30PL,127 provide 100A continuous drain current, enabling use in applications requiring higher current margins or future design scaling.

Category C - Lower Current Capacity (10.2A to 30A): NTP4813NLG and PSMN022-30PL,127 provide reduced current ratings suitable for applications with lower current requirements or space-constrained designs.

All substitute parts maintain the 30V Vdss rating and TO-220-3 package configuration required for mechanical and electrical compatibility.

Parameter Comparison

Parameter	IRF3708	IRLB8721PBF	NTP4813NLG	PSMN022-30PL,127	PSMN2R0-30PL,127	PSMN4R3-30PL,127
Manufacturer	Infineon	Infineon	onsemi	Nexperia	Nexperia	Nexperia
Vdss (V)	30	30	30	30	30	30
Id @ 25°C (A)	62	62	10.2	30	100	100
Rds On (mOhm)	12 @ 15A, 10V	8.7 @ 31A, 10V	13.1 @ 20A, 10V	22 @ 5A, 10V	2.1 @ 15A, 10V	4.3 @ 15A, 10V
Vgs(th) (V)	2 @ 250µA	2.35 @ 25µA	2.5 @ 250µA	2.15 @ 1mA	2.15 @ 1mA	2.15 @ 1mA
Qg (nC)	24 @ 4.5V	13 @ 4.5V	17 @ 11.5V	9 @ 10V	117 @ 10V	41.5 @ 10V
Power Dissipation (W)	87	65	2.4 (Ta) / 60 (Tc)	41	211	103
Operating Temp (°C)	-55 to 175	-55 to 175	-55 to 175	-55 to 175	-55 to 175	-55 to 175
Package	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-220-3
Product Status	Obsolete	Active	Active	Obsolete	Obsolete	Obsolete
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitute - IRLB8721PBF:

The IRLB8721PBF is the recommended primary substitute for the IRF3708. This Infineon Technologies device maintains identical voltage and current ratings (30V, 62A) while offering superior electrical characteristics. The IRLB8721PBF features lower on-state resistance (8.7 mOhm versus 12 mOhm), reduced gate charge (13 nC versus 24 nC), and lower power dissipation (65W versus 87W). Critically, the IRLB8721PBF holds active product status and ROHS3 compliance, ensuring long-term availability and regulatory alignment. The device is supplied in tube packaging and is available in inventory (15,465 pieces).

Secondary Substitutes - Higher Current Capacity:

PSMN4R3-30PL,127 and PSMN2R0-30PL,127 provide 100A continuous drain current capability, exceeding the IRF3708 specification. These devices are suitable for applications requiring current margin expansion or designs with anticipated future current scaling. PSMN4R3-30PL,127 offers moderate on-state resistance (4.3 mOhm) and moderate power dissipation (103W), while PSMN2R0-30PL,127 provides the lowest on-state resistance (2.1 mOhm) but highest power dissipation (211W). Both devices are manufactured by Nexperia USA Inc. and hold ROHS3 compliance. Both are classified as obsolete.

Tertiary Substitute - Lower Current Capacity:

NTP4813NLG, manufactured by onsemi, provides 10.2A continuous drain current and is suitable for applications with reduced current requirements. This device maintains 30V Vdss rating, TO-220-3 package configuration, and active product status with ROHS3 compliance. NTP4813NLG is recommended only when application current requirements are confirmed below 10.2A.

Compliance and Availability Considerations:

All substitute parts maintain the required -55°C to 175°C operating temperature range and TO-220-3 package configuration. IRLB8721PBF is the only active-status substitute with ROHS3 compliance and represents the optimal choice for new designs and production continuity. Obsolete substitutes (PSMN series and PSMN022-30PL,127) should be evaluated for inventory availability and long-term supply risk.

Frequently Asked Questions (FAQ)

Q1: Can IRLB8721PBF directly replace IRF3708 in existing circuit designs?

A: Yes. IRLB8721PBF maintains identical voltage (30V) and current (62A) ratings, operates across the same temperature range (-55°C to 175°C), and uses the same TO-220-3 package configuration. The device is pin-compatible and electrically compatible. Superior electrical characteristics (lower Rds On, lower Qg) provide performance improvement over the original IRF3708.

Q2: What is the difference between the 62A-rated IRLB8721PBF and the 100A-rated PSMN4R3-30PL,127?

A: IRLB8721PBF is rated for 62A continuous drain current, matching the IRF3708 specification. PSMN4R3-30PL,127 is rated for 100A continuous drain current, providing 38A additional current capacity. Selection depends on application current requirements. If the circuit operates at or below 62A, IRLB8721PBF is appropriate. If higher current margin or future scaling is required, PSMN4R3-30PL,127 is suitable, though it requires thermal management evaluation due to higher power dissipation potential.

Q3: Why is NTP4813NLG listed as a substitute if it only provides 10.2A?

A: NTP4813NLG is listed as a substitute for applications where circuit current requirements are confirmed below 10.2A. This device maintains the 30V voltage rating and TO-220-3 package, enabling mechanical compatibility. However, it is not suitable for applications requiring the full 62A capacity of the IRF3708. Substitution with NTP4813NLG requires circuit analysis to confirm current requirements do not exceed 10.2A.

Q4: What is the significance of product status (Active vs. Obsolete)?

A: Active product status indicates ongoing manufacturer support, continued production, and long-term availability. Obsolete status indicates the manufacturer has discontinued production. IRLB8721PBF holds active status, ensuring supply continuity and regulatory support. Obsolete substitutes (PSMN series) carry supply risk and should be evaluated for inventory availability before selection.

Q5: Are all substitute parts ROHS3 compliant?

A: IRLB8721PBF, NTP4813NLG, PSMN022-30PL,127, PSMN2R0-30PL,127, and PSMN4R3-30PL,127 are all ROHS3 compliant. The original IRF3708 is RoHS non-compliant. Substitution with any listed alternative improves regulatory compliance for new designs and production batches.

Q6: How does on-state resistance (Rds On) affect circuit performance?

A: On-state resistance determines power dissipation during conduction. Lower Rds On reduces heat generation and improves efficiency. IRLB8721PBF (8.7 mOhm) provides lower Rds On than IRF3708 (12 mOhm), reducing power loss. PSMN2R0-30PL,127 (2.1 mOhm) provides the lowest Rds On among substitutes but is rated for 100A, requiring thermal analysis for 62A applications.

Q7: What is gate charge (Qg) and why does it matter?

A: Gate charge represents the total charge required to switch the MOSFET from off to on state. Lower gate charge enables faster switching and reduces drive circuit power requirements. IRLB8721PBF (13 nC) provides lower gate charge than IRF3708 (24 nC), improving switching performance and reducing driver stress.

Q8: Can substitute parts be mixed in the same circuit or production batch?

A: Mixing substitute parts with different electrical characteristics (particularly Rds On and Qg) in parallel configurations may result in unequal current distribution and thermal stress. If multiple devices are used in parallel, all devices should be from the same part number to ensure matched electrical characteristics and balanced current sharing.

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