BD242A-S Equivalent & Substitute Parts

Part Overview

The BD242A-S is a PNP bipolar junction transistor manufactured by Bourns Inc., rated for 60 V collector-emitter breakdown voltage and 3 A maximum collector current in a TO-220 through-hole package. This device is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design support and procurement continuity. Substitute parts are selected based on matching or exceeding the electrical and mechanical specifications of the original device while maintaining compatibility with existing circuit designs.

Key Parameters

Parameter	BD242A-S Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	60	V
Current - Collector (Ic) (Max)	3	A
Power - Max	2	W
Vce Saturation (Max)	1.2 @ 600mA, 3A	V
Current - Collector Cutoff (Max)	300	µA
DC Current Gain (hFE) (Min)	25 @ 1A, 4V	—
Operating Temperature Range	-65 to 150	°C (TJ)
Package / Case	TO-220-3	—
Mounting Type	Through Hole	—

Substitute Part Grouping Explanation

Substitute parts for the BD242A-S are grouped into two categories based on electrical parameter compatibility:

Category 1: Direct Electrical Equivalents (Matched Current Rating) Parts with maximum collector current of 3 A and 60 V breakdown voltage maintain identical current-handling capacity and voltage rating. These substitutes are pin-compatible in TO-220-3 packages and require no circuit modifications.

Category 2: Higher Current Capability Substitutes (Uprated Current) Parts with maximum collector current exceeding 3 A (6 A or 10 A) provide enhanced current capacity while maintaining the 60 V voltage specification. These substitutes are electrically compatible and pin-compatible but deliver increased design margin for current-limited applications.

Key Parameters Determining Substitution:

Transistor polarity: PNP (mandatory match)
Voltage - Collector Emitter Breakdown: 60 V (minimum requirement)
Current - Collector (Ic) (Max): 3 A (minimum requirement)
Package / Case: TO-220-3 (mechanical compatibility)
Mounting Type: Through Hole (mechanical compatibility)

Parameter Comparison

Parameter	BD242A-S	TIP32AG	TIP42A	TIP42AG	MJE2955T	MJE2955TG
Manufacturer	Bourns Inc.	onsemi	NTE Electronics, Inc	onsemi	NTE Electronics, Inc	onsemi
Transistor Type	PNP	PNP	PNP	PNP	PNP	PNP
Voltage - Collector Emitter Breakdown (Max)	60 V	60 V	60 V	60 V	60 V	60 V
Current - Collector (Ic) (Max)	3 A	3 A	6 A	6 A	10 A	10 A
Power - Max	2 W	2 W	2 W	2 W	75 W	75 W
Vce Saturation (Max)	1.2V @ 600mA, 3A	1.2V @ 375mA, 3A	1.5V @ 600mA, 6A	1.5V @ 600mA, 6A	8V @ 3.3A, 10A	8V @ 3.3A, 10A
Current - Collector Cutoff (Max)	300 µA	300 µA	700 µA	700 µA	700 µA	700 µA
DC Current Gain (hFE) (Min)	25 @ 1A, 4V	10 @ 3A, 4V	15 @ 3A, 4V	15 @ 3A, 4V	20 @ 4A, 4V	20 @ 4A, 4V
Frequency - Transition	—	3 MHz	—	3 MHz	2 MHz	2 MHz
Operating Temperature Range	-65 to 150°C (TJ)	-65 to 150°C (TJ)	150°C (TJ)	-65 to 150°C (TJ)	-55 to 150°C (TJ)	-55 to 150°C (TJ)
Package / Case	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-220-3
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

Direct Equivalent (Matched Current Rating):

TIP32AG (onsemi) is the primary direct equivalent to BD242A-S. This part maintains identical maximum collector current (3 A) and voltage rating (60 V), with matching power dissipation (2 W) and operating temperature range (-65 to 150°C). TIP32AG is ROHS3 compliant and carries active product status, ensuring long-term availability and supply chain continuity. The TO-220-3 package provides mechanical compatibility without circuit board modifications.

Higher Current Capability Substitutes:

TIP42AG (onsemi) provides 6 A maximum collector current while maintaining 60 V voltage rating and 2 W power dissipation. This part is ROHS3 compliant with active product status and operating temperature range of -65 to 150°C, matching the original device's thermal specifications.

MJE2955TG (onsemi) offers the highest current capacity at 10 A with 60 V voltage rating. This part is ROHS3 compliant and active. However, power dissipation increases to 75 W, requiring thermal management considerations in applications previously designed for 2 W devices. Operating temperature range is -55 to 150°C, providing a reduced lower temperature limit compared to the original specification.

Compliance Considerations:

All recommended substitutes maintain ROHS3 compliance status. TIP42A and MJE2955T (NTE Electronics) are RoHS non-compliant and should be selected only when RoHS compliance is not a design requirement. TIP32AG and TIP42AG are preferred for applications requiring ROHS3 certification.

Frequently Asked Questions (FAQ)

Q: Can TIP32AG be used as a direct replacement for BD242A-S without circuit modifications?

A: Yes. TIP32AG matches the BD242A-S in maximum collector current (3 A), collector-emitter breakdown voltage (60 V), power dissipation (2 W), and operating temperature range (-65 to 150°C). The TO-220-3 package is identical, and pin configuration is compatible. No circuit modifications are required.

Q: What is the difference between TIP42AG and MJE2955TG?

A: Both parts are PNP transistors with 60 V breakdown voltage and TO-220-3 packaging. TIP42AG is rated for 6 A maximum collector current and 2 W power dissipation. MJE2955TG is rated for 10 A maximum collector current and 75 W power dissipation. MJE2955TG requires thermal management design considerations due to higher power rating. Selection depends on application current requirements and thermal design constraints.

Q: Is the BD242A-S still available for procurement?

A: BD242A-S is classified as obsolete. Active substitute parts (TIP32AG, TIP42AG, MJE2955TG) are recommended for new designs and ongoing procurement to ensure supply chain continuity.

Q: What are the RoHS compliance implications of substitute selection?

A: TIP32AG, TIP42AG, and MJE2955TG are ROHS3 compliant. TIP42A and MJE2955T are RoHS non-compliant. For applications requiring RoHS certification, select only ROHS3 compliant substitutes.

Q: Can MJE2955TG be used in applications designed for 2 W power dissipation?

A: MJE2955TG is rated for 75 W power dissipation and is electrically compatible with BD242A-S. However, the higher power rating indicates different thermal characteristics. In applications where the original 2 W device was thermally marginal, MJE2955TG provides enhanced thermal margin. In applications with adequate thermal design, MJE2955TG operates within specification without modification.

Q: What is the operating temperature range difference between BD242A-S and substitute parts?

A: BD242A-S operates from -65 to 150°C. TIP32AG and TIP42AG match this range (-65 to 150°C). MJE2955T and MJE2955TG operate from -55 to 150°C, providing a reduced lower temperature limit of 10°C. For applications requiring operation below -55°C, TIP32AG or TIP42AG are required.

Q: Are all substitute parts available in the same packaging options?

A: All substitute parts are available in TO-220-3 through-hole packages. Packaging formats differ by manufacturer: TIP32AG and TIP42AG are supplied in tubes; TIP42A and MJE2955T are supplied in bags; MJE2955TG is supplied in tubes. Packaging format does not affect electrical compatibility or circuit board integration.

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