IRLZ44Z N-Channel 55V 51A MOSFET Equivalent & Substitute Parts

Part Overview

The IRLZ44Z is an N-Channel MOSFET manufactured by Infineon Technologies, rated for 55V drain-to-source voltage and 51A continuous drain current in a TO-220AB through-hole package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

The IRLZ44Z belongs to the HEXFET® series and is designed for applications requiring moderate voltage and current switching capabilities with low on-resistance characteristics. Due to its obsolete status, active alternative components from current manufacturers are required to maintain design continuity and ensure long-term component availability.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	55	V
Continuous Drain Current (Id) @ 25°C	51	A
On-Resistance (Rds On) @ 31A, 10V	13.5	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	3	V
Gate Charge (Qg) @ 5V	36	nC
Power Dissipation (Max)	80	W
Operating Temperature Range	-55 to 175	°C
Package Type	TO-220AB	—
Mounting Type	Through Hole	—
RoHS Status	Non-compliant	—

Substitute Part Grouping Explanation

Substitution of the IRLZ44Z is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Drain-to-Source Voltage (Vdss): Must be equal to or greater than 55V
Continuous Drain Current (Id): Must be equal to or greater than 51A
Package Type: TO-220AB or TO-220-3 (compatible through-hole packages)
Mounting Type: Through Hole
Operating Temperature Range: Must encompass -55°C to 175°C

Secondary Compatibility Parameters:

On-Resistance (Rds On): Lower values indicate improved performance
Gate Charge (Qg): Affects switching speed and gate drive requirements
Power Dissipation: Higher ratings provide thermal margin
RoHS Compliance: Preferred for modern applications

Substitute parts are grouped into two categories: Direct Equivalents (matching or closely similar electrical specifications) and Enhanced Alternatives (higher current or power ratings within the same voltage class).

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Id @ 25°C (A)	Rds On (mOhm)	Qg (nC)	Pd Max (W)	Package	Status	RoHS
IRLZ44Z	Infineon	55	51	13.5	36	80	TO-220AB	Obsolete	Non-compliant
STP55NF06L	STMicroelectronics	60	55	18	37	95	TO-220	Active	Compliant
STP60NF06	STMicroelectronics	60	60	16	73	110	TO-220	Active	Compliant
STP60NF06L	STMicroelectronics	60	60	14	66	110	TO-220	Active	Compliant
HUF75332P3	onsemi	55	60	19	85	145	TO-220-3	Active	Compliant
HUF75339P3	onsemi	55	75	12	130	200	TO-220-3	Active	Compliant
HUF75344P3	onsemi	55	75	8	210	285	TO-220-3	Active	Compliant
IRLZ44PBF	Vishay Siliconix	60	50	28	66	150	TO-220AB	Active	Compliant
IXTP70N075T2	IXYS	75	70	12	46	150	TO-220-3	Active	Compliant
PHP191NQ06LT,127	Nexperia USA Inc.	55	75	3.7	95.6	300	TO-220AB	Obsolete	Compliant

Engineering Selection Recommendations

Direct Voltage-Matched Substitutes (55V Class):

The HUF75332P3, HUF75339P3, and HUF75344P3 from onsemi maintain the 55V Vdss rating of the IRLZ44Z while providing higher current ratings (60A to 75A) and improved power dissipation (145W to 285W). These devices are active products with RoHS3 compliance. The HUF75344P3 offers the lowest on-resistance (8 mOhm) and highest power rating, suitable for applications requiring enhanced thermal performance.

Voltage-Elevated Substitutes (60V Class):

The STMicroelectronics STripFET™ II series (STP55NF06L, STP60NF06, STP60NF06L) and Vishay IRLZ44PBF provide 60V ratings with current capabilities from 55A to 60A. These are active products with RoHS3 compliance. The STP60NF06L offers the lowest on-resistance (14 mOhm) in this group. The 5V voltage margin above the IRLZ44Z specification provides additional design headroom.

High-Performance Alternative (75V Class):

The IXYS IXTP70N075T2 operates at 75V with 70A continuous current and features the TrenchT2™ technology. This device provides the highest voltage margin and is suitable for applications with elevated supply voltages or requiring additional safety margin.

Compliance Considerations:

All recommended active substitutes comply with RoHS3 and REACH regulations. The IRLZ44Z is RoHS non-compliant; migration to compliant alternatives is necessary for new designs and long-term procurement. The PHP191NQ06LT,127 from Nexperia is RoHS3 compliant but classified as obsolete.

Package Compatibility:

TO-220AB and TO-220-3 packages are mechanically compatible for through-hole mounting applications. Pin configurations are identical for standard N-Channel MOSFETs in these packages.

Frequently Asked Questions (FAQ)

Q: Can the IRLZ44Z be directly replaced with any of these substitutes?

A: Direct replacement depends on circuit requirements. All listed substitutes meet or exceed the 55V/51A minimum specifications. However, differences in on-resistance, gate charge, and power dissipation may affect circuit performance. Verify that the substitute's electrical characteristics are compatible with your gate drive circuit and thermal management design.

Q: What is the difference between TO-220AB and TO-220-3 packages?

A: Both packages are mechanically and electrically compatible for N-Channel MOSFET applications. TO-220AB and TO-220-3 refer to the same three-pin through-hole configuration with identical pin assignments (Gate, Drain, Source). The designation difference reflects manufacturer nomenclature variations.

Q: Why do some substitutes have higher on-resistance than the IRLZ44Z?

A: On-resistance varies based on die design, process technology, and gate voltage. The IRLZ44Z specifies 13.5 mOhm at 31A/10V. Some substitutes specify on-resistance at different current levels (e.g., 30A or 75A), making direct comparison difficult. Lower on-resistance generally indicates lower power dissipation and heat generation, but higher-rated devices may have acceptable performance for your application.

Q: Is RoHS compliance mandatory for my application?

A: RoHS3 compliance is required for products sold in the European Union and many other markets. If your application or end-market requires RoHS compliance, select from the active, compliant alternatives. The IRLZ44Z is non-compliant; long-term use in new designs is not recommended.

Q: Which substitute offers the best thermal performance?

A: The HUF75344P3 provides the highest power dissipation rating (285W) and lowest on-resistance (8 mOhm at 75A/10V), resulting in the lowest heat generation per ampere. The PHP191NQ06LT,127 also offers excellent thermal characteristics (300W, 3.7 mOhm) but is obsolete.

Q: Can I use a higher-voltage-rated device (60V or 75V) in place of the 55V IRLZ44Z?

A: Yes. Higher voltage ratings provide additional design margin and are electrically compatible. The 60V and 75V devices will operate correctly in circuits designed for 55V operation. Verify that gate drive voltage and other circuit parameters remain within specification for the substitute device.

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

A: Gate charge is the total charge required to switch the MOSFET from off to on. Higher gate charge requires more gate drive current and energy. The IRLZ44Z specifies 36 nC; substitutes range from 37 nC to 210 nC. If your gate drive circuit has limited current capability, select a substitute with lower gate charge to ensure reliable switching.

Q: Are there any pin-compatibility issues between these substitutes?

A: All listed substitutes use standard TO-220AB or TO-220-3 pin configurations (Gate, Drain, Source). Pin assignments are identical. No modifications to PCB layout or wiring are required for package-compatible substitutes.

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