IRFZ44ZSPBF N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The IRFZ44ZSPBF is an N-Channel MOSFET manufactured by Infineon Technologies, rated for 55V drain-to-source voltage and 51A continuous drain current in a D2PAK surface mount package. This device is discontinued at DiGi Electronics, necessitating identification of functionally equivalent alternatives for ongoing design support and production requirements. Substitute parts must maintain compatibility with existing PCB layouts, thermal management requirements, and electrical performance specifications within the D2PAK package form factor.

Key Parameters

Parameter	IRFZ44ZSPBF Value	Unit
FET Type	N-Channel	—
Drain-to-Source Voltage (Vdss)	55	V
Continuous Drain Current (Id) @ 25°C	51	A
On-State Resistance (Rds On) @ 31A, 10V	13.9	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	4	V
Gate Charge (Qg) @ 10V	43	nC
Power Dissipation (Max)	80	W
Operating Temperature Range	-55 to 175	°C
Package Type	D2PAK (TO-263-3)	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the IRFZ44ZSPBF is determined by the following critical parameters:

Primary Compatibility Criteria:

FET Type: N-Channel (all substitutes must be N-Channel)
Package: D2PAK (TO-263-3) surface mount form factor
Drain-to-Source Voltage (Vdss): Minimum 55V (equal or higher voltage rating acceptable)
Continuous Drain Current (Id): Minimum 50A (equal or higher current rating acceptable)
Operating Temperature: -55°C to 175°C (matching or exceeding range)
RoHS Compliance: ROHS3 Compliant

Secondary Performance Parameters:

On-State Resistance (Rds On): Lower values indicate improved efficiency
Gate Charge (Qg): Lower values reduce switching losses
Power Dissipation: Higher ratings provide thermal margin

Substitute parts are grouped into two categories based on voltage rating alignment:

Category A (55V–60V Rating): Direct voltage-class substitutes with minimal circuit redesign risk. These parts operate within the original 55V specification window and are preferred for drop-in replacement scenarios.

Category B (75V–100V Rating): Higher voltage-rated substitutes offering increased design margin. These parts require verification that higher Vdss does not conflict with circuit protection schemes or component stress limits.

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Id @ 25°C (A)	Rds On (mOhm)	Qg (nC)	Pd Max (W)	Status	Package
IRFZ44ZSPBF	Infineon	55	51	13.9 @ 31A, 10V	43 @ 10V	80	Discontinued	D2PAK
IRFZ44SPBF	Vishay Siliconix	60	50	28 @ 31A, 10V	67 @ 10V	150	Active	D2PAK
IRFZ44STRLPBF	Vishay Siliconix	60	50	28 @ 31A, 10V	67 @ 10V	150	Active	D2PAK
PSMN015-60BS,118	Nexperia USA Inc.	60	50	14.8 @ 15A, 10V	20.9 @ 10V	86	Active	D2PAK
PSMN7R6-60BS,118	Nexperia USA Inc.	60	92	7.8 @ 25A, 10V	38.7 @ 10V	149	Active	D2PAK
STB55NF06T4	STMicroelectronics	60	50	18 @ 27.5A, 10V	60 @ 10V	110	Active	D2PAK
STB60NF06T4	STMicroelectronics	60	60	16 @ 30A, 10V	66 @ 10V	110	Active	D2PAK
STB75NF75LT4	STMicroelectronics	75	75	11 @ 37.5A, 10V	90 @ 5V	300	Active	D2PAK
STB75NF75T4	STMicroelectronics	75	80	11 @ 40A, 10V	160 @ 10V	300	Active	D2PAK
IPB50N10S3L16ATMA1	Infineon Technologies	100	50	15.4 @ 50A, 10V	64 @ 10V	100	Active	D2PAK

Engineering Selection Recommendations

For Direct Replacement (Minimum Circuit Modification):

Select IRFZ44SPBF or IRFZ44STRLPBF (Vishay Siliconix) when PCB layout and thermal design are optimized for the original IRFZ44ZSPBF. Both parts maintain 60V Vdss rating (5V margin above original 55V specification) and 50A continuous drain current. The primary trade-off is increased on-state resistance (28 mOhm vs. 13.9 mOhm), resulting in higher conduction losses. These parts are Active status with full RoHS3 compliance and unlimited moisture sensitivity level (MSL 1).

For Improved Efficiency (Recommended for New Designs):

Select PSMN015-60BS,118 (Nexperia USA Inc.) for applications prioritizing low conduction losses. This part delivers 14.8 mOhm on-state resistance at 15A, 10V, approaching the original IRFZ44ZSPBF performance (13.9 mOhm at 31A, 10V). Gate charge is significantly reduced to 20.9 nC, lowering switching losses. Rated for 60V, 50A, 86W power dissipation. Active status with ROHS3 compliance.

For High Current Applications (>51A Requirement):

Select PSMN7R6-60BS,118 (Nexperia USA Inc.) when continuous drain current exceeds 51A. This part is rated for 92A continuous drain current with superior on-state resistance of 7.8 mOhm at 25A, 10V. Power dissipation rating of 149W accommodates higher thermal loads. Maintains 60V Vdss and D2PAK package compatibility. Active status with ROHS3 compliance.

For Elevated Voltage Margin (Design Robustness):

Select STB75NF75T4 (STMicroelectronics) when circuit topology requires higher voltage headroom or when transient overvoltage protection is critical. Rated for 75V Vdss, 80A continuous drain current, with 11 mOhm on-state resistance at 40A, 10V. Power dissipation of 300W provides substantial thermal margin. Active status with ROHS3 compliance and STripFET™ II series designation.

For Maximum Voltage Rating (100V Class):

Select IPB50N10S3L16ATMA1 (Infineon Technologies, OptiMOS™ series) when circuit design requires 100V Vdss rating. Rated for 50A continuous drain current with 15.4 mOhm on-state resistance at 50A, 10V. Power dissipation of 100W. Active status with ROHS3 compliance. This part is suitable for applications with higher supply voltage or greater transient overvoltage exposure.

Compliance Verification:

All recommended substitute parts maintain ROHS3 compliance, unlimited moisture sensitivity level (MSL 1), REACH unaffected status, and EAR99 export classification, matching the original IRFZ44ZSPBF regulatory profile.

Frequently Asked Questions (FAQ)

Q1: Can IRFZ44SPBF directly replace IRFZ44ZSPBF without PCB modification?

A: Yes. Both parts use D2PAK (TO-263-3) package with identical pin configuration and footprint. Electrical performance differs in on-state resistance (28 mOhm vs. 13.9 mOhm) and gate charge (67 nC vs. 43 nC). Circuit operation is maintained, but conduction and switching losses increase. Thermal design verification is required if the original design operated near maximum junction temperature.

Q2: What is the voltage rating difference between 55V and 60V rated parts?

A: The IRFZ44ZSPBF is rated for 55V maximum drain-to-source voltage. Substitute parts rated 60V provide 5V additional margin above the original specification. This margin accommodates transient overvoltage events and provides design robustness. Parts rated 75V or 100V provide greater margin but may introduce higher parasitic capacitance and gate charge, affecting switching performance.

Q3: Why does PSMN7R6-60BS,118 have higher current rating (92A) than the original (51A)?

A: PSMN7R6-60BS,118 is a different device within the same voltage class (60V) optimized for higher current applications. The higher current rating reflects improved die design and lower on-state resistance (7.8 mOhm vs. 13.9 mOhm). This part is suitable for applications requiring current levels exceeding 51A or for designs prioritizing efficiency over the original current specification.

Q4: Are there performance differences between IRFZ44SPBF (tube packaging) and IRFZ44STRLPBF (tape & reel)?

A: No electrical or performance differences exist between these two Vishay Siliconix parts. Both are identical IRFZ44 devices with 60V, 50A rating and 28 mOhm on-state resistance. The difference is packaging format: IRFZ44SPBF is supplied in tube packaging, while IRFZ44STRLPBF is supplied in tape & reel format. Selection depends on production volume and assembly equipment compatibility.

Q5: What is the impact of increased gate charge on circuit design?

A: Gate charge (Qg) determines the charge required to switch the MOSFET on or off. Higher gate charge increases switching time and energy dissipation in the gate driver circuit. IRFZ44ZSPBF has 43 nC gate charge, while IRFZ44SPBF has 67 nC. If the gate driver has limited current capability, increased gate charge may slow switching transitions, increasing switching losses. Verify gate driver specifications before substitution.

Q6: Can STB75NF75T4 (75V rated) be used in a 55V circuit?

A: Yes. Higher voltage-rated MOSFETs operate safely in lower voltage circuits. STB75NF75T4 rated for 75V can be used in 55V applications. The higher voltage rating provides additional design margin and transient overvoltage protection. However, higher voltage-rated devices typically have increased parasitic capacitance (3700 pF vs. 1420 pF for IRFZ44ZSPBF), which may increase switching losses and gate charge requirements. Thermal and switching performance verification is required.

Q7: What does "Active" product status mean for substitute parts?

A: Active status indicates the part is currently manufactured and available from authorized distributors. All recommended substitute parts carry Active status, ensuring long-term supply availability and production support. The original IRFZ44ZSPBF is marked Discontinued at DiGi Electronics, making Active-status substitutes essential for ongoing production.

Q8: Are all substitute parts RoHS3 compliant?

A: Yes. All recommended substitute parts are ROHS3 compliant, matching the original IRFZ44ZSPBF compliance profile. RoHS3 compliance confirms absence of restricted substances (lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls, polybrominated diphenyl ethers) and compliance with EU Directive 2011/65/EU as amended by Directive (EU) 2015/863.

Q9: What is the significance of MSL 1 (Unlimited) moisture sensitivity level?

A: MSL 1 indicates unlimited shelf life without moisture absorption precautions. Parts with MSL 1 do not require dry-pack storage or baking before reflow soldering. All recommended substitute parts carry MSL 1 rating, eliminating moisture management requirements and simplifying supply chain handling.

Q10: How should on-state resistance (Rds On) values be compared across different measurement conditions?

A: On-state resistance varies with gate voltage (Vgs) and drain current (Id). IRFZ44ZSPBF specifies 13.9 mOhm at 31A, 10V. PSMN015-60BS,118 specifies 14.8 mOhm at 15A, 10V. Direct comparison requires normalizing to identical measurement conditions. Lower Rds On at higher current levels indicates superior performance. Consult device datasheets for complete Rds On vs. Id and Vgs characteristics before final selection.

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