IRFZ44NSTRR N-Channel MOSFET 55V 49A D2PAK Equivalent & Substitute Parts

Part Overview

The IRFZ44NSTRR is an N-Channel MOSFET manufactured by Infineon Technologies in the HEXFET® series, rated for 55V drain-to-source voltage and 49A continuous drain current in D2PAK surface mount packaging. This device is classified as obsolete product status. Due to its obsolete classification and limited inventory availability (636 pcs), identification of equivalent and substitute parts is necessary for ongoing design support, production continuity, and long-term component sourcing strategies. Substitute parts maintain functional compatibility through matching or superior electrical parameters within the N-Channel MOSFET category.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	55	V
Continuous Drain Current (Id) @ 25°C	49	A (Tc)
On-Resistance (Rds On) @ 25A, 10V	17.5	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	4	V
Gate Charge (Qg) @ 10V	63	nC
Input Capacitance (Ciss) @ 25V	1470	pF
Power Dissipation (Max)	3.8 (Ta), 94 (Tc)	W
Operating Temperature Range	-55 to 175	°C (TJ)
Package Type	D2PAK (TO-263-3)	Surface Mount
FET Type	N-Channel	MOSFET

Substitute Part Grouping Explanation

Substitute parts are classified into two categories based on electrical parameter compatibility with the IRFZ44NSTRR:

Parametric Equivalent (Direct Replacement): Parts maintaining identical or functionally equivalent electrical specifications across all critical parameters: Vdss, Id, Rds On, Vgs(th), Qg, Ciss, and operating temperature range. These parts are pin-compatible in D2PAK packaging and require no circuit modifications.

Manufacturer Recommended Substitutes (Enhanced Performance): Parts with superior or equivalent electrical ratings that exceed the IRFZ44NSTRR specifications. These include higher Vdss ratings (60V vs. 55V), equal or higher Id ratings (50A-55A vs. 49A), and improved power dissipation characteristics. All maintain D2PAK packaging compatibility and identical pin configuration.

Key Parameters Determining Substitution Validity:

Drain-to-Source Voltage (Vdss): Substitute must equal or exceed 55V
Continuous Drain Current (Id): Substitute must equal or exceed 49A
Gate Threshold Voltage (Vgs(th)): Must remain within ±20V gate voltage specification
Package Type: Must be D2PAK (TO-263-3) surface mount
Operating Temperature: Must support -55°C to 175°C range
Pin Configuration: Must maintain 3-pin D2PAK lead structure

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Id (A)	Rds On (mOhm)	Vgs(th) (V)	Qg (nC)	Ciss (pF)	Power Diss. (W)	Status	RoHS
IRFZ44NSTRR	Infineon	55	49	17.5	4	63	1470	94 (Tc)	Obsolete	Non-compliant
IRFZ44NSTRLPBF	Infineon	55	49	17.5	4	63	1470	94 (Tc)	Active	ROHS3
IRFZ44SPBF	Vishay Siliconix	60	50	28	4	67	1900	150 (Tc)	Active	ROHS3
IRFZ44STRLPBF	Vishay Siliconix	60	50	28	4	67	1900	150 (Tc)	Active	ROHS3
PSMN015-60BS,118	Nexperia USA Inc.	60	50	14.8	4	20.9	1220	86 (Tc)	Active	ROHS3
STB55NF06LT4	STMicroelectronics	60	55	18	4.7	37	1700	95 (Tc)	Active	ROHS3
STB55NF06T4	STMicroelectronics	60	50	18	4	60	1300	110 (Tc)	Active	ROHS3

Engineering Selection Recommendations

Primary Recommendation: IRFZ44NSTRLPBF

The IRFZ44NSTRLPBF is the direct parametric equivalent to the IRFZ44NSTRR, manufactured by Infineon Technologies. This part maintains identical electrical specifications across all critical parameters: 55V Vdss, 49A Id, 17.5mOhm Rds On, and 94W power dissipation. The primary distinction is product status classification: IRFZ44NSTRLPBF is active with ROHS3 compliance, whereas the original part is obsolete and RoHS non-compliant. Inventory availability is substantially higher (21,134 pcs vs. 636 pcs). This part requires no circuit modifications and provides direct functional replacement with improved compliance status.

Secondary Recommendations: Vishay Siliconix IRFZ44SPBF and IRFZ44STRLPBF

Both Vishay Siliconix parts (IRFZ44SPBF and IRFZ44STRLPBF) provide enhanced electrical performance with 60V Vdss rating and 50A Id rating, exceeding the original 55V/49A specification. These parts are functionally compatible with superior voltage and current margins. The trade-off is increased on-resistance (28mOhm vs. 17.5mOhm) and higher input capacitance (1900pF vs. 1470pF). Both are active products with ROHS3 compliance. IRFZ44SPBF is packaged in tube format; IRFZ44STRLPBF is supplied in tape and reel format.

Tertiary Recommendations: Nexperia PSMN015-60BS,118 and STMicroelectronics STB55NF06LT4/STB55NF06T4

The Nexperia PSMN015-60BS,118 offers superior on-resistance performance (14.8mOhm) and lower gate charge (20.9nC), with 60V/50A ratings. The STMicroelectronics STB55NF06LT4 provides the highest current rating (55A) with 60V Vdss and improved power dissipation (95W). STB55NF06T4 maintains 50A rating with 110W power dissipation. All three parts are active products with ROHS3 compliance and D2PAK packaging compatibility. These options are suitable for applications requiring enhanced thermal performance or lower switching losses.

Compliance Consideration:

All recommended substitute parts carry ROHS3 compliance certification, addressing the RoHS non-compliant status of the original IRFZ44NSTRR. This compliance upgrade is mandatory for new designs and production transitions in regulated markets.

Frequently Asked Questions (FAQ)

Q1: Can IRFZ44NSTRLPBF be used as a direct replacement for IRFZ44NSTRR without circuit modifications?

A: Yes. IRFZ44NSTRLPBF is a parametric equivalent with identical electrical specifications. No circuit modifications are required. The part is pin-compatible in D2PAK packaging and maintains the same gate threshold voltage, on-resistance, and power dissipation characteristics. The primary difference is product status (active vs. obsolete) and RoHS compliance level.

Q2: What is the difference between IRFZ44SPBF and IRFZ44STRLPBF?

A: Both parts are electrically identical with 60V/50A ratings and 28mOhm on-resistance. The difference is packaging format: IRFZ44SPBF is supplied in tube packaging, while IRFZ44STRLPBF is supplied in tape and reel format. Selection depends on production volume and assembly equipment compatibility. Both are Vishay Siliconix products with ROHS3 compliance.

Q3: Why do some substitute parts have higher Vdss ratings (60V vs. 55V)?

A: Higher Vdss ratings provide increased voltage margin and design safety without compromising functionality. A 60V-rated device can operate safely in 55V applications with improved reliability headroom. This is a beneficial characteristic for substitute selection, as it maintains backward compatibility while reducing risk of voltage stress failures.

Q4: How does on-resistance (Rds On) affect circuit performance?

A: On-resistance directly impacts power dissipation and heat generation. Lower Rds On values reduce I²R losses during conduction. The IRFZ44NSTRR has 17.5mOhm Rds On, while Vishay alternatives have 28mOhm (higher losses) and Nexperia PSMN015-60BS,118 has 14.8mOhm (lower losses). Selection depends on thermal budget and efficiency requirements of the application.

Q5: Are all substitute parts compatible with the D2PAK package footprint?

A: Yes. All listed substitute parts use D2PAK (TO-263-3) surface mount packaging with identical pin configuration (3 leads: Gate, Drain, Source). PCB footprints are directly compatible without modification. Mounting type is surface mount for all parts.

Q6: What is the significance of gate charge (Qg) differences between parts?

A: Gate charge affects switching speed and gate drive circuit requirements. Lower Qg values (e.g., PSMN015-60BS,118 at 20.9nC) enable faster switching with lower gate drive power. Higher Qg values (e.g., IRFZ44SPBF at 67nC) require more gate charge but may offer other performance benefits. Selection depends on switching frequency and gate drive circuit design.

Q7: Can STB55NF06LT4 (55A rating) replace IRFZ44NSTRR (49A rating) in all applications?

A: Yes. STB55NF06LT4 has superior current rating (55A vs. 49A), providing increased current margin. This is a beneficial substitution for applications operating near the 49A limit. The part maintains 60V Vdss, D2PAK packaging, and -55°C to 175°C operating range. Higher current capability does not create compatibility issues in lower-current applications.

Q8: What does ROHS3 compliance mean for the substitute parts?

A: ROHS3 compliance indicates conformance to Restriction of Hazardous Substances Directive 3, restricting lead, cadmium, mercury, and other hazardous materials. All recommended substitute parts carry ROHS3 certification, addressing the RoHS non-compliant status of the original IRFZ44NSTRR. This is mandatory for new designs and production in regulated markets.

Q9: How should I select between multiple substitute options?

A: Selection criteria are: (1) Product Status: Prioritize active products over obsolete; (2) Compliance: Require ROHS3 certification; (3) Electrical Performance: Match or exceed original specifications; (4) Packaging: Confirm D2PAK compatibility; (5) Inventory: Verify availability for production volume; (6) Application-Specific: Consider on-resistance for thermal performance, gate charge for switching speed, and power dissipation for thermal design.

Q10: Is inventory availability a factor in substitute selection?

A: Yes. Inventory availability affects production continuity and lead times. IRFZ44NSTRLPBF has 21,134 pcs available (vs. 636 pcs for the original), providing superior supply security. STB55NF06T4 has 18,852 pcs available. Higher inventory levels reduce supply chain risk for ongoing production and future design iterations.

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