2STF2340 Equivalent & Substitute Parts

Part Overview

The 2STF2340 is a PNP bipolar junction transistor manufactured by STMicroelectronics, rated for 40 V collector-emitter breakdown voltage and 3 A maximum collector current. The device is packaged in SOT-89-3 surface mount configuration with a maximum power dissipation of 1.4 W and transition frequency of 100 MHz. The 2STF2340 is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and production continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	40	V
Current - Collector (Ic) (Max)	3	A
Power - Max	1.4	W
Frequency - Transition	100	MHz
Package / Case	TO-243AA (SOT-89-3)	—
Mounting Type	Surface Mount	—
Operating Temperature (Max)	150	°C
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the 2STF2340 is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor type must be PNP
Collector-emitter breakdown voltage must be greater than or equal to 40 V
Maximum collector current must be greater than or equal to 3 A
Package must be SOT-89-3 (TO-243AA) surface mount
RoHS3 compliance required

Secondary Compatibility Factors:

Power dissipation rating
Transition frequency
DC current gain (hFE)
Vce saturation characteristics
Operating temperature range

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

Category A - Full Current Rating Match (3 A): Parts with 3 A maximum collector current provide direct functional equivalence for applications requiring the full 3 A specification.

Category B - Reduced Current Rating (1 A to 2 A): Parts with lower maximum collector current ratings are suitable for applications where the circuit design operates below the 3 A threshold, provided all other electrical parameters remain compatible.

Category C - Voltage Derating (30 V): Parts with 30 V breakdown voltage are suitable only for applications where the circuit design operates below 30 V, representing a voltage derating condition.

Parameter Comparison

Part Number	Manufacturer	Ic (Max)	Vce(br)	Power (Max)	Frequency	Vce Sat @ Ib, Ic	hFE (Min)	Status
2STF2340	STMicroelectronics	3 A	40 V	1.4 W	100 MHz	350mV @ 150mA, 3A	180 @ 1A, 2V	Obsolete
FCX1151ATA	Diodes Incorporated	3 A	40 V	2 W	145 MHz	300mV @ 250mA, 3A	250 @ 500mA, 2V	Active
FCX790ATA	Diodes Incorporated	2 A	40 V	2 W	100 MHz	450mV @ 50mA, 2A	300 @ 10mA, 2V	Active
FCX591ATA	Diodes Incorporated	1 A	40 V	1 W	150 MHz	500mV @ 100mA, 1A	300 @ 100mA, 5V	Active
BCX51TA	Diodes Incorporated	1 A	45 V	1 W	150 MHz	500mV @ 50mA, 500mA	40 @ 150mA, 2V	Active
DXT3906-13	Diodes Incorporated	200 mA	40 V	1 W	250 MHz	400mV @ 5mA, 50mA	100 @ 10mA, 1V	Active
PXT3906-TP	Micro Commercial Co	200 mA	40 V	500 mW	250 MHz	400mV @ 5mA, 50mA	100 @ 10mA, 1V	Active
PBSS5330X,135	Nexperia USA Inc.	3 A	30 V	1.6 W	100 MHz	320mV @ 300mA, 3A	175 @ 1A, 2V	Active

Engineering Selection Recommendations

Primary Recommendation - Direct Equivalent:

The FCX1151ATA (Diodes Incorporated) is the primary substitute for the 2STF2340. This part maintains identical collector current (3 A) and collector-emitter breakdown voltage (40 V) specifications. The FCX1151ATA is active in production status with ROHS3 compliance and improved power dissipation (2 W versus 1.4 W). The part is available in Cut Tape and Digi-Reel packaging formats, matching the original supply chain compatibility of the 2STF2340.

Secondary Recommendation - Reduced Current Applications:

The FCX790ATA (Diodes Incorporated) is suitable for applications where circuit design operates at or below 2 A collector current. This part maintains 40 V breakdown voltage and provides equivalent transition frequency (100 MHz) to the original device. The FCX790ATA offers improved power dissipation (2 W) and is active in production with ROHS3 compliance.

Tertiary Recommendation - Low Current Applications:

The FCX591ATA (Diodes Incorporated) is suitable for applications where circuit design operates at or below 1 A collector current. This part maintains 40 V breakdown voltage and provides enhanced transition frequency (150 MHz). The FCX591ATA is active in production with ROHS3 compliance.

Voltage-Derated Application:

The PBSS5330X,135 (Nexperia USA Inc.) maintains 3 A collector current and 100 MHz transition frequency but operates at 30 V maximum breakdown voltage. This part is suitable only for applications where the circuit design operates below 30 V. The PBSS5330X,135 carries automotive qualification (AEC-Q100) and is active in production with ROHS3 compliance.

Not Recommended:

The BCX51TA, DXT3906-13, and PXT3906-TP parts do not meet the full electrical specification of the 2STF2340 due to reduced collector current ratings (1 A or 200 mA) and are suitable only for applications with significantly reduced current requirements.

Frequently Asked Questions (FAQ)

Q: Can the FCX1151ATA directly replace the 2STF2340 in all applications?

A: The FCX1151ATA meets all primary electrical specifications (3 A, 40 V, SOT-89-3 package) and is the direct functional equivalent. However, circuit validation is required to confirm compatibility with specific application requirements, particularly regarding Vce saturation characteristics and DC current gain performance at the intended operating point.

Q: What is the difference between the FCX1151ATA and FCX790ATA?

A: The FCX1151ATA is rated for 3 A maximum collector current, while the FCX790ATA is rated for 2 A. Both maintain 40 V breakdown voltage and SOT-89-3 packaging. The FCX790ATA is suitable for applications where the circuit design operates at or below 2 A. The FCX1151ATA provides higher current capacity for applications requiring the full 3 A specification.

Q: Why is the PBSS5330X,135 listed as a substitute if it has only 30 V breakdown voltage?

A: The PBSS5330X,135 maintains the 3 A collector current and 100 MHz transition frequency of the 2STF2340. However, the 30 V breakdown voltage represents a derating condition. This part is suitable only for applications where the circuit design operates below 30 V. Applications requiring the full 40 V specification must use alternatives such as the FCX1151ATA.

Q: Are all substitute parts available in the same packaging format as the 2STF2340?

A: All substitute parts use the SOT-89-3 (TO-243AA) surface mount package, ensuring mechanical compatibility. However, packaging formats (Tape & Reel, Cut Tape, Digi-Reel, or Bulk) vary by part number and supplier. Verify packaging availability with the component supplier for production requirements.

Q: What is the significance of the Vce saturation parameter in selecting a substitute?

A: Vce saturation indicates the voltage drop across the transistor when operating in saturation mode. Lower Vce saturation values result in reduced power dissipation and improved efficiency. The FCX1151ATA exhibits lower Vce saturation (300 mV at 3 A) compared to the 2STF2340 (350 mV at 3 A), providing improved performance in switching applications.

Q: Can the DXT3906-13 or PXT3906-TP be used in place of the 2STF2340?

A: The DXT3906-13 and PXT3906-TP are rated for only 200 mA maximum collector current, compared to the 2STF2340 specification of 3 A. These parts are suitable only for applications where the circuit design operates at or below 200 mA. Applications requiring 3 A operation must use the FCX1151ATA or FCX790ATA.

Q: What compliance certifications apply to the substitute parts?

A: All substitute parts listed are ROHS3 compliant and REACH unaffected. The PBSS5330X,135 carries additional automotive qualification (AEC-Q100). Verify compliance requirements for specific application standards before final part selection.

Q: How does the transition frequency affect part selection?

A: Transition frequency (fT) indicates the maximum frequency at which the transistor maintains useful gain. The 2STF2340 operates at 100 MHz. Substitute parts with higher transition frequencies (FCX591ATA at 150 MHz, DXT3906-13 and PXT3906-TP at 250 MHz) provide enhanced high-frequency performance. Parts with equal or lower transition frequency maintain equivalent performance for the original application bandwidth.

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