IRFZ44ZS N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The IRFZ44ZS is an N-Channel MOSFET manufactured by Infineon Technologies, rated for 55V drain-to-source voltage with 51A continuous drain current in D2PAK surface mount packaging. This device is classified as obsolete product status. Due to its obsolete classification, equivalent and substitute parts from active manufacturers are necessary to maintain design continuity and ensure long-term component availability for new production and field replacements.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	55	V
Continuous Drain Current (Id) @ 25°C	51	A (Tc)
On-State Resistance (Rds On) @ 31A, 10V	13.9	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	4	V
Power Dissipation (Max)	80	W (Tc)
Operating Temperature Range	-55 to 175	°C (TJ)
Package Type	D2PAK (TO-263-3)	Surface Mount
FET Type	N-Channel	—
Technology	MOSFET (Metal Oxide)	—

Substitute Part Grouping Explanation

Substitution of the IRFZ44ZS is determined by strict alignment of the following electrical and mechanical parameters:

Primary Substitution Criteria:

Drain-to-Source Voltage (Vdss): Minimum 55V (equal or higher voltage rating required)
Continuous Drain Current (Id): Minimum 51A at 25°C (equal or higher current rating required)
On-State Resistance (Rds On): Comparable or lower resistance at specified gate voltage
Gate Threshold Voltage (Vgs(th)): Within ±1V of 4V nominal
Package Type: D2PAK (TO-263-3) surface mount only
Operating Temperature Range: Minimum -55°C to 175°C
FET Type: N-Channel only
Technology: MOSFET (Metal Oxide) only

Secondary Considerations:

Gate Charge (Qg): Lower values preferred for faster switching
Input Capacitance (Ciss): Lower values preferred for reduced drive requirements
Power Dissipation: Higher ratings provide thermal margin

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

Category A (55V–60V Rating): Parts with Vdss of 55V to 60V maintain direct voltage compatibility with the original IRFZ44ZS design envelope. These include BUK7613-60E,118; IRFZ44SPBF; IRFZ44STRLPBF; PSMN015-60BS,118; STB55NF06T4; STB60NF06T4; and FDB13AN06A0.

Category B (75V Rating): Parts with Vdss of 75V provide higher voltage margin and are suitable for applications where increased voltage headroom is acceptable. These include BUK9616-75B,118 and STB75NF75LT4.

Category C (60V High-Current): PSMN7R6-60BS,118 offers significantly higher drain current (92A) at 60V rating, suitable for applications requiring current margin beyond the original 51A specification.

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Id @ 25°C (A)	Rds On (mOhm)	Vgs(th) (V)	Qg (nC)	Ciss (pF)	Pd Max (W)	Status	RoHS
IRFZ44ZS	Infineon	55	51	13.9 @ 31A	4 @ 250µA	43 @ 10V	1420 @ 25V	80	Obsolete	Non-compliant
BUK7613-60E,118	Nexperia	60	58	13 @ 15A	4 @ 1mA	22.9 @ 10V	1730 @ 25V	96	Active	ROHS3
BUK9616-75B,118	Nexperia	75	67	14 @ 25A	2 @ 1mA	35 @ 5V	4034 @ 25V	157	Active	ROHS3
FDB13AN06A0	onsemi	60	62	13.5 @ 62A	4 @ 250µA	29 @ 10V	1350 @ 25V	115	Active	ROHS3
IRFZ44SPBF	Vishay Siliconix	60	50	28 @ 31A	4 @ 250µA	67 @ 10V	1900 @ 25V	150	Active	ROHS3
IRFZ44STRLPBF	Vishay Siliconix	60	50	28 @ 31A	4 @ 250µA	67 @ 10V	1900 @ 25V	150	Active	ROHS3
PSMN015-60BS,118	Nexperia	60	50	14.8 @ 15A	4 @ 1mA	20.9 @ 10V	1220 @ 30V	86	Active	ROHS3
PSMN7R6-60BS,118	Nexperia	60	92	7.8 @ 25A	4 @ 1mA	38.7 @ 10V	2651 @ 30V	149	Active	ROHS3
STB55NF06T4	STMicroelectronics	60	50	18 @ 27.5A	4 @ 250µA	60 @ 10V	1300 @ 25V	110	Active	ROHS3
STB60NF06T4	STMicroelectronics	60	60	16 @ 30A	4 @ 250µA	66 @ 10V	1810 @ 25V	110	Active	ROHS3
STB75NF75LT4	STMicroelectronics	75	75	11 @ 37.5A	2.5 @ 250µA	90 @ 5V	4300 @ 25V	300	Active	ROHS3

Engineering Selection Recommendations

For Direct Replacement (Minimum Design Changes):

Select from Category A substitutes when the original 55V design envelope must be preserved. BUK7613-60E,118 and FDB13AN06A0 provide the closest electrical alignment with improved on-state resistance characteristics and active product status. Both devices are ROHS3 compliant and carry AEC-Q101 automotive qualification (BUK7613-60E,118) or active status with high inventory availability (FDB13AN06A0).

PSMN015-60BS,118 offers comparable current rating (50A) with lower gate charge (20.9 nC) and reduced input capacitance (1220 pF), reducing gate drive requirements. This part is ROHS3 compliant and actively manufactured by Nexperia.

For Applications Requiring Current Margin:

PSMN7R6-60BS,118 provides 92A continuous drain current at 60V, delivering 81% higher current capacity than the original IRFZ44ZS. This part exhibits superior on-state resistance (7.8 mOhm) and is suitable for designs where thermal or current headroom is critical. ROHS3 compliant and actively produced.

STB60NF06T4 delivers 60A at 60V with 16 mOhm on-state resistance and is actively manufactured by STMicroelectronics with ROHS3 compliance.

For Applications Accepting Higher Voltage Rating:

BUK9616-75B,118 and STB75NF75LT4 operate at 75V, providing 36% higher voltage margin. Both are ROHS3 compliant and actively produced. STB75NF75LT4 offers exceptional power dissipation (300W) and current capacity (75A), suitable for high-power applications. BUK9616-75B,118 carries AEC-Q101 automotive qualification.

Packaging and Compliance:

All substitute parts maintain D2PAK (TO-263-3) surface mount packaging, ensuring mechanical compatibility. All active substitutes are ROHS3 compliant, addressing environmental and regulatory requirements that the obsolete IRFZ44ZS does not meet.

Frequently Asked Questions (FAQ)

Q1: Can IRFZ44SPBF and IRFZ44STRLPBF be used as direct replacements for IRFZ44ZS?

Both parts share the same base part number (IRFZ44) and operate at 60V with 50A continuous drain current. However, on-state resistance is higher (28 mOhm vs. 13.9 mOhm), resulting in increased power dissipation. These parts are suitable for applications where the higher Rds On is acceptable. The primary difference between IRFZ44SPBF and IRFZ44STRLPBF is packaging: SPBF is supplied in Tube, while STRLPBF is supplied in Tape & Reel. Both are ROHS3 compliant and actively produced by Vishay Siliconix.

Q2: What is the advantage of PSMN7R6-60BS,118 over other 60V substitutes?

PSMN7R6-60BS,118 provides the highest continuous drain current (92A) among 60V alternatives, with the lowest on-state resistance (7.8 mOhm @ 25A, 10V). This combination delivers superior current handling and reduced conduction losses. The trade-off is higher input capacitance (2651 pF), which increases gate drive requirements. This part is optimal for high-current applications where thermal efficiency is critical.

Q3: Should I select a 75V-rated part if my design operates below 55V?

Yes, 75V-rated parts (BUK9616-75B,118 and STB75NF75LT4) are electrically compatible with designs rated for 55V operation. The higher voltage rating provides additional safety margin and does not degrade performance at lower voltages. However, these parts exhibit higher input capacitance and gate charge, requiring stronger gate drive circuits. Select 75V parts only if gate drive capability and thermal budget permit the increased capacitive loading.

Q4: What is the difference between BUK7613-60E,118 and PSMN015-60BS,118?

Both parts operate at 60V with 50A–58A continuous drain current and comparable on-state resistance. BUK7613-60E,118 carries AEC-Q101 automotive qualification and is part of the TrenchMOS™ series, making it suitable for automotive applications. PSMN015-60BS,118 offers lower gate charge (20.9 nC) and reduced input capacitance (1220 pF), reducing gate drive power. Select BUK7613-60E,118 for automotive designs; select PSMN015-60BS,118 for applications prioritizing gate drive efficiency.

Q5: Are all substitute parts RoHS compliant?

All active substitute parts listed are ROHS3 compliant. The original IRFZ44ZS is RoHS non-compliant. Compliance with ROHS3 is mandatory for new designs and many OEM procurement specifications.

Q6: What is the impact of higher gate charge on circuit design?

Gate charge (Qg) determines the total charge required to switch the MOSFET from off to on state. Higher gate charge (e.g., IRFZ44SPBF at 67 nC) requires stronger gate drive circuits and increases switching losses. Lower gate charge (e.g., PSMN015-60BS,118 at 20.9 nC) reduces gate drive power and switching losses. For high-frequency switching applications, select parts with lower gate charge.

Q7: Can I use STB55NF06T4 or STB60NF06T4 as substitutes?

Yes. STB55NF06T4 provides 50A at 60V with 18 mOhm on-state resistance. STB60NF06T4 provides 60A at 60V with 16 mOhm on-state resistance. Both are part of the STripFET™ II series and are ROHS3 compliant. STB60NF06T4 offers higher current capacity and is preferred for applications requiring additional current margin.

Q8: What is the significance of input capacitance (Ciss) in MOSFET selection?

Input capacitance affects gate drive circuit design and switching speed. Higher Ciss (e.g., STB75NF75LT4 at 4300 pF) requires higher gate drive current to achieve fast switching. Lower Ciss (e.g., PSMN015-60BS,118 at 1220 pF) reduces gate drive requirements and is preferred for battery-powered or low-power gate drive applications. For high-frequency switching, lower Ciss is advantageous.

Q9: Is FDB13AN06A0 suitable for high-reliability applications?

FDB13AN06A0 is manufactured by onsemi as part of the PowerTrench® series and is ROHS3 compliant. It provides 62A continuous drain current at 60V with 13.5 mOhm on-state resistance. The part is actively produced with high inventory availability (15,265 pcs). It is suitable for high-reliability applications where active product status and component availability are critical.

Q10: What packaging options are available for substitute parts?

All substitute parts are supplied in D2PAK (TO-263-3) surface mount packaging, maintaining mechanical compatibility with the original IRFZ44ZS. Packaging variants differ by supplier: Tape & Reel (TR) for automated assembly, Cut Tape (CT) for manual assembly, and Tube for lower-volume applications. Select packaging based on production volume and assembly process requirements.

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