IRFZ44NSPBF N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The IRFZ44NSPBF is an N-Channel MOSFET manufactured by Infineon Technologies, rated for 55V drain-to-source voltage with 49A continuous drain current in D2PAK surface mount packaging. This device is part of the HEXFET® series and is currently discontinued at DiGi Electronics, necessitating identification of functionally equivalent alternatives for ongoing design support and procurement.

The IRFZ44NSPBF operates across a temperature range of -55°C to 175°C (TJ) and complies with RoHS3 and REACH standards. With 5230 pieces in current inventory, substitute parts must maintain electrical compatibility while meeting modern component availability requirements.

Key Parameters

Parameter	Value	Unit	Specification Basis
Drain-to-Source Voltage (Vdss)	55	V	Maximum rated voltage
Continuous Drain Current (Id) @ 25°C	49	A	Tc rating
On-State Resistance (Rds On) @ 25A, 10V	17.5	mOhm	Maximum at specified conditions
Gate Threshold Voltage (Vgs(th)) @ 250µA	4	V	Maximum
Gate Charge (Qg) @ 10V	63	nC	Maximum
Input Capacitance (Ciss) @ 25V	1470	pF	Maximum
Power Dissipation (Tc)	94	W	Maximum at case temperature
Operating Temperature Range	-55 to 175	°C	TJ junction temperature
Package Type	D2PAK (TO-263-3)	—	Surface mount, 2 leads + tab
FET Type	N-Channel	—	MOSFET technology

Substitute Part Grouping Explanation

Substitution of the IRFZ44NSPBF is determined by the following electrical and mechanical criteria:

Primary Substitution Criteria:

Drain-to-Source Voltage (Vdss) must equal or exceed 55V
Continuous Drain Current (Id) must equal or exceed 49A
On-State Resistance (Rds On) must not exceed the original specification to maintain thermal performance
Gate Threshold Voltage (Vgs(th)) must be compatible with existing gate drive circuits
Package must be D2PAK (TO-263-3) surface mount for mechanical compatibility
FET Type must be N-Channel MOSFET
Operating temperature range must span -55°C to 175°C

Substitutes are grouped into two categories:

Category A - Direct Voltage Class Substitutes (55V-60V Rating): These parts maintain the original 55V voltage class or operate at 60V, providing direct functional replacement with minimal circuit redesign. Parts include IRFZ44SPBF, IRFZ44STRLPBF, STB55NF06LT4, STB55NF06T4, and PSMN015-60BS,118.

Category B - Higher Voltage Class Substitute (100V Rating): The IPB50N10S3L16ATMA1 operates at 100V, providing enhanced voltage margin for applications requiring higher transient voltage protection. This part is suitable where circuit topology permits higher voltage rating without performance degradation.

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Id @ 25°C (A)	Rds On (mOhm)	Vgs(th) (V)	Qg (nC)	Ciss (pF)	Pd Tc (W)	Package	Status
IRFZ44NSPBF	Infineon	55	49	17.5	4	63	1470	94	D2PAK	Discontinued
IRFZ44SPBF	Vishay Siliconix	60	50	28	4	67	1900	150	D2PAK	Active
IRFZ44STRLPBF	Vishay Siliconix	60	50	28	4	67	1900	150	D2PAK	Active
STB55NF06LT4	STMicroelectronics	60	55	18	4.7	37	1700	95	D2PAK	Active
STB55NF06T4	STMicroelectronics	60	50	18	4	60	1300	110	D2PAK	Active
PSMN015-60BS,118	Nexperia USA Inc.	60	50	14.8	4	20.9	1220	86	D2PAK	Active
IPB50N10S3L16ATMA1	Infineon	100	50	15.4	2.4	64	4180	100	D2PAK	Active

Engineering Selection Recommendations

For Direct Replacement (Same Voltage Class):

IRFZ44SPBF and IRFZ44STRLPBF (Vishay Siliconix) are functionally equivalent to IRFZ44NSPBF with identical gate threshold voltage (4V) and similar gate charge characteristics. Both are Active status with RoHS3 compliance. The primary difference is packaging format: IRFZ44SPBF is supplied in Tube, while IRFZ44STRLPBF is supplied in Tape & Reel. On-state resistance is higher (28 mOhm vs. 17.5 mOhm), requiring thermal analysis for power-dissipative applications.

STB55NF06T4 (STMicroelectronics) provides improved on-state resistance (18 mOhm) and lower gate charge (60 nC), with higher power dissipation rating (110W Tc). Gate threshold voltage is 4V, matching the original. This part is suitable for applications prioritizing switching efficiency.

PSMN015-60BS,118 (Nexperia USA Inc.) offers the lowest on-state resistance (14.8 mOhm) among 60V alternatives and lowest input capacitance (1220 pF), with reduced gate charge (20.9 nC). Gate threshold voltage is 4V. This part is optimal for high-frequency switching applications.

STB55NF06LT4 (STMicroelectronics) supports the highest drain current (55A) among 60V options with 18 mOhm on-state resistance. Gate threshold voltage is 4.7V, requiring verification of gate drive circuit compatibility.

For Higher Voltage Margin Applications:

IPB50N10S3L16ATMA1 (Infineon, OptiMOS™ series) operates at 100V with 50A continuous current and 15.4 mOhm on-state resistance. Gate threshold voltage is 2.4V, requiring gate drive circuit adjustment. Input capacitance is significantly higher (4180 pF), affecting switching speed. This part is suitable where circuit topology permits 100V operation and gate drive modification is feasible.

Compliance and Availability:

All substitute parts are RoHS3 compliant and REACH unaffected. All operate across -55°C to 175°C temperature range. Inventory availability ranges from 1311 to 18852 pieces, ensuring procurement continuity.

Frequently Asked Questions (FAQ)

Q1: Can IRFZ44SPBF directly replace IRFZ44NSPBF without circuit modification?

A: IRFZ44SPBF is mechanically and electrically compatible for direct substitution. Both are N-Channel MOSFETs in D2PAK packaging with 4V gate threshold voltage and ±20V maximum gate voltage. The 60V rating provides 5V additional voltage margin over the 55V original. However, on-state resistance is higher (28 mOhm vs. 17.5 mOhm), requiring thermal analysis for applications operating near maximum current ratings.

Q2: What is the difference between IRFZ44SPBF and IRFZ44STRLPBF?

A: Both parts are electrically identical with identical electrical specifications. The difference is packaging format: IRFZ44SPBF is supplied in Tube packaging, while IRFZ44STRLPBF is supplied in Tape & Reel format. Selection depends on assembly process requirements and volume handling.

Q3: Why does PSMN015-60BS,118 have lower on-state resistance than the original IRFZ44NSPBF?

A: PSMN015-60BS,118 represents a newer generation of MOSFET technology with improved semiconductor processing. Lower on-state resistance (14.8 mOhm vs. 17.5 mOhm) reduces conduction losses and heat generation. This part is suitable for applications where thermal performance is critical.

Q4: Is IPB50N10S3L16ATMA1 suitable as a drop-in replacement?

A: IPB50N10S3L16ATMA1 is not a drop-in replacement due to different gate threshold voltage (2.4V vs. 4V). Gate drive circuits designed for 4V threshold may not provide adequate gate voltage margin with this part. Additionally, significantly higher input capacitance (4180 pF vs. 1470 pF) affects switching speed and gate drive current requirements. This part requires gate drive circuit redesign and is suitable only where 100V voltage rating provides system-level benefits.

Q5: What are the key parameters determining substitution compatibility?

A: Substitution compatibility is determined by: (1) Drain-to-Source Voltage rating equal to or exceeding 55V, (2) Continuous Drain Current equal to or exceeding 49A, (3) D2PAK surface mount package, (4) N-Channel MOSFET technology, (5) Gate threshold voltage compatible with existing gate drive circuits, and (6) Operating temperature range spanning -55°C to 175°C. On-state resistance and gate charge affect performance but do not prevent substitution if thermal and switching requirements are met.

Q6: Which substitute part offers the best thermal performance?

A: STB55NF06T4 offers the highest power dissipation rating (110W Tc) among 60V alternatives, combined with 18 mOhm on-state resistance. PSMN015-60BS,118 provides the lowest on-state resistance (14.8 mOhm), minimizing conduction losses. Selection depends on whether thermal margin or conduction efficiency is the priority.

Q7: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed are RoHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements for electronic component procurement.

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