2STN2550 Equivalent & Substitute Parts

Part Overview

The 2STN2550 is a PNP bipolar junction transistor manufactured by STMicroelectronics, designed for surface mount applications in the SOT-223 package. This component operates at a maximum collector current of 5 A and collector-emitter breakdown voltage of 50 V, with a maximum power dissipation of 1.6 W. The 2STN2550 is classified as obsolete, making identification of equivalent substitute parts necessary for ongoing design support, maintenance, and production continuity. Substitute parts must maintain functional compatibility across critical electrical parameters including current rating, voltage rating, and saturation characteristics while accommodating the surface mount form factor.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) (Max)	5	A
Voltage - Collector Emitter Breakdown (Max)	50	V
Vce Saturation (Max)	550	mV @ 300mA, 3A
Power - Max	1.6	W
Operating Temperature (TJ)	150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-261-4, TO-261AA	—
Supplier Device Package	SOT-223	—
RoHS Status	ROHS3 Compliant	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitute parts for the 2STN2550 are selected based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Critical Matching Parameters:

Transistor Type: PNP configuration
Current Rating: Minimum 5 A collector current capability
Voltage Rating: Minimum 50 V collector-emitter breakdown voltage
Package Type: Surface mount SOT-223 family
Saturation Characteristics: Vce(sat) performance at specified base and collector currents
Mounting Compatibility: TO-261-4 or TO-261AA case outline

Acceptable Variation Parameters:

Power dissipation may exceed 1.6 W (higher ratings are acceptable)
Transition frequency may vary (not specified for main part)
Operating temperature range may exceed the main part specification
DC current gain (hFE) may vary within active region operation

Substitute parts must satisfy all critical matching parameters to ensure direct functional replacement in existing circuit designs without modification to PCB layout or component footprint.

Parameter Comparison

Parameter	2STN2550 (Main)	FZT951TA	NZT751
Manufacturer	STMicroelectronics	Diodes Incorporated	Fairchild Semiconductor
Transistor Type	PNP	PNP	PNP
Current - Collector (Ic) (Max)	5 A	5 A	4 A
Voltage - Collector Emitter Breakdown (Max)	50 V	60 V	60 V
Vce Saturation (Max)	550 mV @ 300mA, 3A	460 mV @ 500mA, 5A	500 mV @ 200mA, 2A
Current - Collector Cutoff (Max)	100 nA	50 nA	100 nA
DC Current Gain (hFE) (Min)	110 @ 2A, 2V	100 @ 2A, 1V	40 @ 2A, 2V
Power - Max	1.6 W	3 W	1.2 W
Frequency - Transition	—	120 MHz	75 MHz
Operating Temperature (TJ)	150°C	-55°C ~ 150°C	-55°C ~ 150°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Package / Case	TO-261-4, TO-261AA	TO-261-4, TO-261AA	TO-261-4, TO-261AA
Supplier Device Package	SOT-223	SOT-223-3	SOT-223-4
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Not specified
Product Status	Obsolete	Active	Active

Engineering Selection Recommendations

FZT951TA (Diodes Incorporated): The FZT951TA is a direct functional substitute for the 2STN2550. It meets or exceeds all critical electrical parameters: 5 A maximum collector current, 60 V breakdown voltage (exceeds 50 V requirement), and compatible SOT-223-3 package footprint. The FZT951TA demonstrates superior saturation performance (460 mV versus 550 mV) and lower collector cutoff current (50 nA versus 100 nA). The component is ROHS3 compliant and maintains active product status, ensuring long-term availability and supply chain stability. The extended operating temperature range (-55°C to 150°C) provides additional thermal margin. This part is recommended as the primary substitute for new designs and production continuity.

NZT751 (Fairchild Semiconductor): The NZT751 provides functional substitution with specific limitations. The maximum collector current rating of 4 A falls below the 5 A requirement of the 2STN2550, restricting its use to applications where peak collector current does not exceed 4 A. The 60 V breakdown voltage exceeds the main part specification. The NZT751 maintains compatible SOT-223-4 package footprint and active product status. The lower DC current gain (40 versus 110) may require circuit design verification in applications dependent on transistor gain characteristics. This part is suitable for applications with reduced current requirements and where design margin permits lower gain operation.

Both substitute parts maintain surface mount compatibility and RoHS compliance status. Selection between FZT951TA and NZT751 depends on specific application current requirements and gain specifications.

Frequently Asked Questions (FAQ)

Q: Can the FZT951TA directly replace the 2STN2550 without PCB modification?

A: Yes. The FZT951TA maintains compatible TO-261-4 and TO-261AA case outline dimensions and SOT-223 family package footprint. No PCB layout changes are required for direct substitution.

Q: What is the primary reason the 2STN2550 requires a substitute?

A: The 2STN2550 is classified as obsolete. Substitute parts ensure design continuity, production support, and long-term component availability for maintenance and new production runs.

Q: Is the NZT751 suitable for all 2STN2550 applications?

A: The NZT751 is suitable only for applications where the maximum collector current does not exceed 4 A. Applications requiring the full 5 A rating must use the FZT951TA or equivalent 5 A rated substitute.

Q: How do the saturation characteristics compare between the main part and substitutes?

A: The FZT951TA exhibits lower saturation voltage (460 mV at 500mA, 5A) compared to the 2STN2550 (550 mV at 300mA, 3A), indicating improved switching performance. The NZT751 saturation voltage (500 mV at 200mA, 2A) falls between the two, measured at different operating points.

Q: Are both substitute parts RoHS compliant?

A: The FZT951TA is ROHS3 compliant. The NZT751 RoHS status is not specified in available documentation. Compliance verification is required for applications with RoHS mandates.

Q: What is the significance of the different SOT-223 package variants (SOT-223, SOT-223-3, SOT-223-4)?

A: All variants maintain compatible TO-261-4 and TO-261AA case outlines and surface mount footprints. The numeric suffix indicates internal pin configuration differences that do not affect PCB layout compatibility for standard three-terminal transistor applications.

Q: Can the higher power rating of the FZT951TA (3 W versus 1.6 W) cause issues in existing designs?

A: No. Higher power dissipation ratings indicate greater thermal capability and do not create compatibility issues. The FZT951TA can operate safely in applications designed for the 1.6 W 2STN2550.

Q: What is the impact of the extended operating temperature range in substitute parts?

A: The FZT951TA and NZT751 both support -55°C to 150°C operation, compared to the 2STN2550 specification of 150°C maximum. This extended range provides additional thermal margin and is beneficial for applications operating at temperature extremes.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message