NZT44H8 Equivalent & Substitute Parts

Part Overview

The NZT44H8 is an NPN bipolar junction transistor manufactured by onsemi, designed for surface mount applications in the SOT-223-4 package. This device operates at a maximum collector current of 8 A with a 60 V collector-emitter breakdown voltage and delivers 1.5 W maximum power dissipation. The NZT44H8 is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design requirements and production continuity. Active alternative parts with comparable electrical characteristics are available from multiple manufacturers.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) (Max)	8	A
Voltage - Collector Emitter Breakdown (Max)	60	V
Power - Max	1.5	W
Frequency - Transition	50	MHz
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Surface Mount	—
Package / Case	TO-261-4, TO-261AA	—
RoHS Status	ROHS3 Compliant	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the NZT44H8 is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

Transistor Type: NPN configuration required
Voltage - Collector Emitter Breakdown (Max): 60 V minimum
Current - Collector (Ic) (Max): Equal to or greater than required circuit current
Operating Temperature Range: -55°C to 150°C (TJ) or compatible subset
Power - Max: Sufficient for application thermal requirements

Mechanical Compatibility Criteria:

Mounting Type: Surface Mount
Package / Case: TO-261-4, TO-261AA, or equivalent footprint compatibility
Supplier Device Package: SOT-223 family packages

Compliance Requirements:

RoHS Status: ROHS3 Compliant
REACH Status: REACH Unaffected

Substitute parts are grouped based on collector current capability and package form factor. Parts with Ic ratings of 6 A or higher provide direct functional replacement for 8 A applications within thermal limits. Parts with lower Ic ratings (1 A) are suitable only for reduced-current applications.

Parameter Comparison

Parameter	NZT44H8	NSS60601MZ4T3G	BSP41,115	FZT851TA	ZXTN2018FTA
Manufacturer	onsemi	onsemi	Nexperia USA Inc.	Diodes Incorporated	Diodes Incorporated
Transistor Type	NPN	NPN	NPN	NPN	NPN
Current - Collector (Ic) (Max)	8 A	6 A	1 A	6 A	5 A
Voltage - Collector Emitter Breakdown (Max)	60 V	60 V	60 V	60 V	60 V
Vce Saturation (Max) @ Ib, Ic	1 V @ 400mA, 8A	300mV @ 600mA, 6A	500mV @ 50mA, 500mA	375mV @ 300mA, 6A	210mV @ 300mA, 6A
Power - Max	1.5 W	800 mW	1.3 W	3 W	1.2 W
Frequency - Transition	50 MHz	100 MHz	100 MHz	130 MHz	130 MHz
Operating Temperature Range	-55 to 150°C (TJ)	-55 to 150°C (TJ)	150°C (TJ)	-55 to 150°C (TJ)	-55 to 150°C (TJ)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	TO-261-4, TO-261AA	TO-261-4, TO-261AA	TO-261-4, TO-261AA	TO-261-4, TO-261AA	TO-236-3, SC-59, SOT-23-3
Supplier Device Package	SOT-223-4	SOT-223 (TO-261)	SOT-223	SOT-223-3	SOT-23-3
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitute: NSS60601MZ4T3G (onsemi)

The NSS60601MZ4T3G is the manufacturer-recommended substitute for the NZT44H8. Both devices are manufactured by onsemi and share identical voltage ratings (60 V) and operating temperature range (-55°C to 150°C). The NSS60601MZ4T3G provides 6 A collector current, which is suitable for applications requiring up to 6 A. This part is in active production status, ensuring long-term availability. The device is ROHS3 compliant and REACH unaffected, matching the compliance profile of the original part.

Secondary Substitute: FZT851TA (Diodes Incorporated)

The FZT851TA is an active alternative manufactured by Diodes Incorporated. It provides 6 A collector current with a 60 V breakdown voltage and operates across the full temperature range (-55°C to 150°C). The FZT851TA offers superior power dissipation capability (3 W) and higher transition frequency (130 MHz) compared to the NZT44H8. This part is suitable for applications requiring enhanced thermal performance. ROHS3 compliance and REACH unaffected status are confirmed.

Tertiary Substitute: ZXTN2018FTA (Diodes Incorporated)

The ZXTN2018FTA is an active alternative from Diodes Incorporated rated for 5 A collector current at 60 V breakdown voltage. This part operates across the full temperature range (-55°C to 150°C) and features a smaller SOT-23-3 package footprint compared to the SOT-223 family. The ZXTN2018FTA is suitable for space-constrained applications and provides 130 MHz transition frequency. ROHS3 compliance and REACH unaffected status are confirmed.

Limited Substitute: BSP41,115 (Nexperia USA Inc.)

The BSP41,115 is an active alternative from Nexperia USA Inc. with automotive-grade qualification (AEC-Q100). This part is rated for 1 A collector current at 60 V and is suitable only for low-current applications. The operating temperature range is specified to 150°C (TJ) without a lower limit specification. This part is not recommended for applications requiring the full 8 A capability of the NZT44H8.

Frequently Asked Questions (FAQ)

Q: Can the NSS60601MZ4T3G directly replace the NZT44H8 in all applications?

A: The NSS60601MZ4T3G is suitable for applications requiring up to 6 A collector current. If the circuit design requires the full 8 A capability of the NZT44H8, the NSS60601MZ4T3G is not appropriate. For 6 A or lower current applications, the NSS60601MZ4T3G provides direct functional replacement with identical voltage and temperature specifications.

Q: What is the difference between SOT-223-4 and SOT-223-3 packages?

A: The SOT-223-4 package includes four leads, while the SOT-223-3 package includes three leads. Both packages are mechanically compatible with TO-261-4 and TO-261AA footprints. The FZT851TA uses the SOT-223-3 configuration. PCB layout verification is required to confirm footprint compatibility before substitution.

Q: Is the ZXTN2018FTA suitable as a direct replacement?

A: The ZXTN2018FTA uses the SOT-23-3 package, which differs from the SOT-223 family packages used by the NZT44H8 and other primary substitutes. The SOT-23-3 package has a smaller footprint and different pin spacing. PCB layout modification is required for this substitution. The ZXTN2018FTA is rated for 5 A collector current, suitable for applications requiring up to 5 A.

Q: Why is the BSP41,115 listed as a limited substitute?

A: The BSP41,115 is rated for only 1 A collector current, significantly lower than the NZT44H8 (8 A) and other primary substitutes (5-6 A). This part is suitable only for low-current applications. Additionally, the operating temperature range specification (150°C TJ) lacks a defined lower temperature limit. The BSP41,115 is not recommended for general replacement of the NZT44H8.

Q: Are all substitute parts RoHS3 compliant?

A: Yes, all substitute parts listed (NSS60601MZ4T3G, BSP41,115, FZT851TA, and ZXTN2018FTA) are ROHS3 compliant and REACH unaffected, matching the compliance status of the NZT44H8.

Q: What is the significance of the transition frequency difference between parts?

A: The NZT44H8 has a 50 MHz transition frequency, while substitute parts range from 100 MHz to 130 MHz. Higher transition frequency indicates faster switching capability. For DC or low-frequency applications, this difference is not significant. For high-frequency switching applications, the higher transition frequency of substitute parts provides improved performance characteristics.

Q: Can I use the FZT851TA in a thermally constrained application?

A: The FZT851TA provides 3 W maximum power dissipation, compared to 1.5 W for the NZT44H8. This higher power rating allows the FZT851TA to operate with lower junction temperature rise in thermally constrained applications. However, actual thermal performance depends on PCB layout, copper area, and thermal management design.

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