STN724 Equivalent & Substitute Parts

Part Overview

The STN724 is an NPN bipolar junction transistor manufactured by STMicroelectronics, designed for surface mount applications in the SOT-223 package. This device operates at a maximum collector current of 3 A and collector-emitter breakdown voltage of 30 V, with a maximum power dissipation of 1.6 W and transition frequency of 100 MHz. The STN724 is classified as obsolete, making identification of functionally equivalent active alternatives necessary for ongoing design support and production continuity.

Key Parameters

Parameter	Value
Transistor Type	NPN
Current - Collector (Ic) (Max)	3 A
Voltage - Collector Emitter Breakdown (Max)	30 V
Power - Max	1.6 W
Frequency - Transition	100 MHz
Mounting Type	Surface Mount
Package / Case	TO-261-4, TO-261AA
Supplier Device Package	SOT-223
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitute parts for the STN724 are selected based on electrical and mechanical compatibility within the following criteria:

Primary Substitution Parameters:

Transistor Type: NPN (required match)
Mounting Type: Surface Mount (required match)
Package / Case: TO-261-4, TO-261AA (required match)
Supplier Device Package: SOT-223 or SOT-223-3 (compatible footprints)
Current - Collector (Ic) (Max): Equal to or greater than 3 A
Voltage - Collector Emitter Breakdown (Max): Equal to or greater than 30 V
Power - Max: Equal to or greater than 1.6 W
Frequency - Transition: Equal to or greater than 100 MHz

Substitute parts meeting these criteria are grouped by manufacturer and electrical performance characteristics. Parts with higher voltage ratings, current ratings, or power dissipation capabilities are direct substitutes, as they operate within the same package footprint and support the same application requirements.

Parameter Comparison

Part Number	Manufacturer	Ic (Max)	Vce Breakdown (Max)	Power (Max)	Frequency (MHz)	Package	Product Status
STN724	STMicroelectronics	3 A	30 V	1.6 W	100	SOT-223	Obsolete
DJT4031N-13	Diodes Incorporated	3 A	40 V	1.2 W	105	SOT-223-3	Active
FZT690BTA	Diodes Incorporated	3 A	45 V	2 W	150	SOT-223-3	Active
FZT849TA	Diodes Incorporated	7 A	30 V	3 W	100	SOT-223-3	Active
NJT4031NT1G	onsemi	3 A	40 V	2 W	215	SOT-223	Active
NJT4031NT3G	onsemi	3 A	40 V	2 W	215	SOT-223	Active
NJV4031NT1G	onsemi	3 A	40 V	2 W	215	SOT-223	Active
NJV4031NT3G	onsemi	3 A	40 V	2 W	215	SOT-223	Active
NSS40301MZ4T1G	onsemi	3 A	40 V	2 W	215	SOT-223	Active
NSS40301MZ4T3G	onsemi	3 A	40 V	2 W	215	SOT-223	Active
NSV40301MZ4T1G	onsemi	3 A	40 V	800 mW	215	SOT-223	Active

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

The onsemi NJT4031NT1G, NJT4031NT3G, NJV4031NT1G, NJV4031NT3G, NSS40301MZ4T1G, and NSS40301MZ4T3G transistors provide direct electrical and mechanical substitution for the STN724. These parts maintain the same collector current rating of 3 A, exceed the 30 V breakdown voltage requirement with 40 V ratings, and offer enhanced power dissipation (2 W) and transition frequency (215 MHz) performance. All are ROHS3 compliant, MSL 1 rated, and carry active product status.

Secondary Substitutes (Voltage/Current Trade-offs):

The Diodes Incorporated DJT4031N-13 operates at 40 V breakdown voltage with 3 A collector current, meeting minimum electrical requirements. However, its 1.2 W power rating falls below the STN724 specification of 1.6 W, requiring thermal design verification for applications approaching maximum power dissipation.

The Diodes Incorporated FZT690BTA provides enhanced performance with 45 V breakdown voltage, 3 A collector current, 2 W power dissipation, and 150 MHz transition frequency. This part is suitable for applications requiring higher voltage margin.

The Diodes Incorporated FZT849TA offers increased collector current capability (7 A) at the original 30 V breakdown voltage with 3 W power dissipation. This part is applicable for designs requiring higher current handling within the same voltage class.

Compliance and Availability:

All substitute parts listed are ROHS3 compliant, REACH unaffected, and carry MSL 1 moisture sensitivity ratings. All active alternatives maintain the same EAR99 export classification and HTSUS coding as the original STN724. Inventory availability ranges from 2,100 to 40,200 units across substitute options.

Frequently Asked Questions (FAQ)

Q: Can the DJT4031N-13 replace the STN724 in all applications?

A: The DJT4031N-13 meets the collector current (3 A) and voltage (40 V) requirements. However, its maximum power dissipation is 1.2 W compared to the STN724's 1.6 W. Applications operating near maximum power levels require thermal analysis to confirm adequate heat dissipation with this substitute.

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

A: Both SOT-223 and SOT-223-3 packages use the TO-261-4 and TO-261AA case designations and are mechanically compatible for PCB mounting. The "-3" designation indicates a specific variant within the SOT-223 family. All listed substitutes are footprint compatible with the STN724.

Q: Why do some substitutes have higher transition frequencies than the STN724?

A: The onsemi NJT4031, NJV4031, and NSS40301 series transistors operate at 215 MHz transition frequency compared to the STN724's 100 MHz. Higher transition frequency indicates faster switching capability and does not prevent substitution in applications designed for the original 100 MHz specification. These parts are backward compatible for lower-frequency applications.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed carry ROHS3 compliance certification, matching the environmental compliance status of the STN724.

Q: Which substitute offers the best direct replacement for the STN724?

A: The onsemi NSS40301MZ4T1G and NSS40301MZ4T3G transistors provide the closest electrical match, with 3 A collector current, 40 V breakdown voltage, 2 W power dissipation, and 215 MHz transition frequency. These parts maintain identical SOT-223 packaging and are available in high inventory quantities (15,520 and 3,023 units respectively).

Q: Can the FZT849TA be used in place of the STN724?

A: The FZT849TA is suitable for applications where higher collector current capability (7 A) is beneficial or required. It maintains the 30 V breakdown voltage of the STN724 and provides enhanced power dissipation (3 W). The higher current rating does not prevent substitution in designs requiring only 3 A operation.

Q: What is the moisture sensitivity level (MSL) rating, and why does it matter?

A: All listed parts carry MSL 1 (Unlimited) rating, indicating no moisture sensitivity restrictions. These transistors can be stored and handled without special moisture control measures, matching the STN724's MSL classification.

Q: Are there any REACH or export restrictions on substitute parts?

A: No. All substitute parts are REACH unaffected and carry the same EAR99 export classification as the STN724, with identical HTSUS coding (8541.29.0075 or 8541.21.0075). No additional compliance documentation is required for substitution.

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