2STN2540-A Equivalent & Substitute Parts

Part Overview

The 2STN2540-A is a PNP bipolar junction transistor manufactured by STMicroelectronics, rated for 40 V collector-emitter breakdown voltage and 5 A maximum collector current in a surface mount SOT-223 package. This device is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and production continuity. The part delivers 1.6 W maximum power dissipation with a minimum DC current gain of 150 at 2 A collector current and 2 V collector-emitter voltage.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) Max	5	A
Voltage - Collector Emitter Breakdown (Max)	40	V
Vce Saturation (Max) @ Ib, Ic	450 mV @ 500 mA, 5 A	—
Current - Collector Cutoff (Max)	100	nA
DC Current Gain (hFE) Min @ Ic, Vce	150 @ 2 A, 2 V	—
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	—
Moisture Sensitivity Level (MSL)	3 (168 Hours)	—
REACH Status	REACH Unaffected	—

Substitute Part Grouping Explanation

Substitution of the 2STN2540-A is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: PNP
Voltage - Collector Emitter Breakdown (Max): 40 V or greater
Current - Collector (Ic) Max: 5 A or greater
Mounting Type: Surface Mount
Package / Case: TO-261-4, TO-261AA (SOT-223 compatible)
Operating Temperature: 150°C or greater

Direct Equivalents maintain all primary parameters with identical or superior electrical ratings and active product status. The 2STN2540 from STMicroelectronics qualifies as a direct equivalent, differing only in packaging format (Cut Tape & Digi-Reel versus Tape & Reel) and moisture sensitivity level (MSL 1 versus MSL 3).

Functional Equivalents meet or exceed the primary substitution criteria but may have variations in secondary parameters such as Vce saturation voltage, DC current gain, power dissipation, or transition frequency. The PBSS5540Z,115 from Nexperia USA Inc. provides superior power rating (2 W versus 1.6 W) and transition frequency (120 MHz) while maintaining the required voltage and current specifications.

Similar Substitutes satisfy the core voltage and mounting requirements but operate at reduced maximum collector current ratings. The BCP51TA (1 A), FZT1151ATA (3 A), and FZT790ATA (3 A) fall into this category. These parts are suitable for applications where the full 5 A rating is not required but the 40 V voltage class and SOT-223 package are essential.

Parameter Comparison

Parameter	2STN2540-A (Main)	2STN2540	PBSS5540Z,115	BCP51TA	FZT1151ATA	FZT790ATA
Manufacturer	STMicroelectronics	STMicroelectronics	Nexperia USA Inc.	Diodes Incorporated	Diodes Incorporated	Diodes Incorporated
Product Status	Obsolete	Active	Active	Active	Active	Active
Transistor Type	PNP	PNP	PNP	PNP	PNP	PNP
Current - Collector (Ic) Max	5 A	5 A	5 A	1 A	3 A	3 A
Voltage - Collector Emitter Breakdown (Max)	40 V	40 V	40 V	45 V	40 V	40 V
Vce Saturation (Max) @ Ib, Ic	450 mV @ 500 mA, 5 A	450 mV @ 500 mA, 5 A	160 mV @ 200 mA, 2 A	500 mV @ 50 mA, 500 mA	300 mV @ 250 mA, 3 A	750 mV @ 50 mA, 2 A
Current - Collector Cutoff (Max)	100 nA	100 nA	100 nA	100 nA	100 nA	100 nA
DC Current Gain (hFE) Min @ Ic, Vce	150 @ 2 A, 2 V	150 @ 2 A, 2 V	150 @ 2 A, 2 V	40 @ 150 mA, 2 V	250 @ 500 mA, 2 V	300 @ 10 mA, 2 V
Power - Max	1.6 W	1.6 W	2 W	2 W	2.5 W	2 W
Frequency - Transition	—	—	120 MHz	125 MHz	145 MHz	100 MHz
Operating Temperature (TJ)	150°C	150°C	150°C	-65°C ~ 150°C	-55°C ~ 150°C	-55°C ~ 150°C
Mounting Type	Surface Mount	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-261-4, TO-261AA	TO-261-4, TO-261AA
Supplier Device Package	SOT-223	SOT-223	SOT-223	SOT-223-3	SOT-223-3	SOT-223-3
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	3 (168 Hours)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

Direct Replacement (Preferred for Pin-Compatible Designs):

The 2STN2540 from STMicroelectronics is the primary direct equivalent. This part maintains identical electrical specifications (5 A collector current, 40 V breakdown voltage, 150 minimum DC current gain) and package configuration (SOT-223). The transition from Tape & Reel to Cut Tape & Digi-Reel packaging does not affect electrical performance. The improved moisture sensitivity level (MSL 1 versus MSL 3) provides extended shelf life and reduced handling constraints. This part is active and ROHS3 compliant, ensuring long-term availability and regulatory compliance.

Functional Equivalent with Enhanced Performance:

The PBSS5540Z,115 from Nexperia USA Inc. meets all primary electrical requirements while providing superior power dissipation (2 W versus 1.6 W) and transition frequency (120 MHz). This part is suitable for applications requiring higher switching speeds or thermal margin. The active product status and MSL 1 rating ensure production continuity and simplified logistics.

Current-Limited Substitutes:

The BCP51TA, FZT1151ATA, and FZT790ATA are suitable only for applications where the maximum collector current requirement does not exceed 1 A, 3 A, and 3 A respectively. These parts maintain the 40 V voltage class and SOT-223 package compatibility but are not suitable for designs requiring the full 5 A rating of the 2STN2540-A. Selection among these three depends on specific current and gain requirements within the reduced current envelope.

All substitute parts carry ROHS3 compliance and REACH unaffected status, meeting current regulatory requirements for electronic component procurement.

Frequently Asked Questions (FAQ)

Q: Can the 2STN2540 directly replace the 2STN2540-A in production?

A: Yes. The 2STN2540 is a direct electrical equivalent with identical collector current (5 A), breakdown voltage (40 V), and DC current gain specifications. The packaging format difference (Cut Tape & Digi-Reel versus Tape & Reel) does not affect circuit performance. The improved moisture sensitivity level (MSL 1) is advantageous for manufacturing and storage.

Q: What is the primary reason to substitute the 2STN2540-A?

A: The 2STN2540-A is classified as obsolete. The 2STN2540 provides continuity with active product status and identical electrical performance, making it the recommended replacement for new designs and ongoing production.

Q: Can the PBSS5540Z,115 replace the 2STN2540-A in all applications?

A: The PBSS5540Z,115 meets all primary electrical requirements (5 A, 40 V, 150 minimum gain) and provides enhanced power rating (2 W) and transition frequency (120 MHz). It is suitable for applications where these enhanced specifications do not create design conflicts. Pin compatibility with SOT-223 package is maintained.

Q: Why are BCP51TA, FZT1151ATA, and FZT790ATA listed as similar rather than direct substitutes?

A: These parts operate at reduced maximum collector current ratings (1 A, 3 A, and 3 A respectively) compared to the 2STN2540-A (5 A). They are suitable only for applications where the design current requirement does not exceed their individual ratings. The 40 V voltage class and SOT-223 package compatibility make them viable for current-limited designs.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts (2STN2540, PBSS5540Z,115, BCP51TA, FZT1151ATA, and FZT790ATA) are ROHS3 compliant and REACH unaffected, meeting current regulatory requirements for electronic component procurement and use.

Q: What is the significance of the moisture sensitivity level (MSL) difference between 2STN2540-A and its substitutes?

A: The 2STN2540-A carries MSL 3 (168 hours), requiring controlled storage and handling conditions. All substitute parts carry MSL 1 (unlimited), eliminating moisture sensitivity constraints and simplifying logistics, storage, and manufacturing processes.

Q: Can the BCP51TA be used in a design originally specified for 2STN2540-A?

A: The BCP51TA is suitable only if the application current requirement does not exceed 1 A. The BCP51TA provides higher breakdown voltage (45 V versus 40 V) and higher transition frequency (125 MHz), but the 1 A maximum collector current is significantly lower than the 2STN2540-A specification. Circuit redesign may be necessary to accommodate this reduced current rating.

Q: What are the key parameters to verify when selecting a substitute for the 2STN2540-A?

A: Verify the following parameters: (1) Transistor type remains PNP, (2) maximum collector current meets or exceeds application requirements, (3) collector-emitter breakdown voltage is 40 V or greater, (4) DC current gain minimum is 150 or greater at the specified operating point, (5) package is SOT-223 compatible, and (6) operating temperature range includes 150°C.

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