BD239A-S Equivalent & Substitute Parts

Part Overview

The BD239A-S is an NPN bipolar junction transistor manufactured by Bourns Inc., packaged in TO-220-3 through-hole configuration. This device is rated for 60 V collector-emitter breakdown voltage and 2 A maximum collector current, with a maximum power dissipation of 2 W. The BD239A-S is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and production applications. Substitute parts must maintain compatibility with existing circuit designs while meeting or exceeding the electrical and thermal specifications of the original device.

Key Parameters

Parameter	BD239A-S Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	60	V
Current - Collector (Ic) (Max)	2	A
Power - Max	2	W
Vce Saturation (Max) @ Ib, Ic	700mV @ 200mA, 1A	V
Current - Collector Cutoff (Max)	300µA	A
DC Current Gain (hFE) (Min) @ Ic, Vce	15 @ 1A, 4V	—
Operating Temperature Range	-65 to 150	°C
Package / Case	TO-220-3	—
Mounting Type	Through Hole	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the BD239A-S are selected based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Critical Matching Parameters:

Transistor Type: NPN (all substitutes must be NPN)
Package / Case: TO-220-3 (mechanical and thermal interface compatibility)
Voltage - Collector Emitter Breakdown (Max): 60 V minimum (circuit voltage rating requirement)
Current - Collector (Ic) (Max): 2 A minimum (load current capability)
Mounting Type: Through Hole (PCB assembly compatibility)

Secondary Compatibility Parameters:

Operating Temperature Range: -65°C to 150°C (thermal operating envelope)
RoHS Status: ROHS3 Compliant (regulatory compliance)

Substitute parts are grouped into two categories:

Category A - Direct Substitutes (Equivalent Performance): Parts with electrical ratings matching or closely aligned to the BD239A-S baseline specifications, suitable for direct replacement in existing designs.

Category B - Upgraded Substitutes (Enhanced Performance): Parts with higher current ratings, power dissipation, or improved electrical characteristics, suitable for applications requiring enhanced performance margins or higher reliability.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) [A]	Vce(br) [V]	Power [W]	Vce Sat @ Ib, Ic	hFE (Min) @ Ic, Vce	Temp Range [°C]	Status
BD239A-S	Bourns Inc.	2	60	2	700mV @ 200mA, 1A	15 @ 1A, 4V	-65 to 150	Obsolete
TIP29AG	onsemi	1	60	2	700mV @ 125mA, 1A	15 @ 1A, 4V	-65 to 150	Active
2ST31A	STMicroelectronics	3	60	40	1.2V @ 375mA, 3A	100 @ 20mA, 4V	-65 to 150	Active
TIP31A	Solid State Inc.	3	60	40	1.2V @ 375mA, 3A	25 @ 1A, 4V	-65 to 150	Active
TIP41AG	onsemi	6	60	2	1.5V @ 600mA, 6A	15 @ 3A, 4V	-65 to 150	Last Time Buy
D44H8	STMicroelectronics	10	60	50	1V @ 400mA, 8A	40 @ 4A, 1V	-65 to 150	Active
MJE3055T	NTE Electronics, Inc	10	60	75	8V @ 3.3A, 10A	20 @ 4A, 4V	-55 to 150	Active
MJE3055TG	onsemi	10	60	75	8V @ 3.3A, 10A	20 @ 4A, 4V	-55 to 150	Active
2N6292G	onsemi	7	70	40	3.5V @ 3A, 7A	30 @ 2A, 4V	-65 to 150	Active
2N6487G	onsemi	15	60	1.8	3.5V @ 5A, 15A	20 @ 5A, 4V	-65 to 150	Active

Engineering Selection Recommendations

For Direct Replacement (Minimum Disruption):

The TIP29AG is the closest functional equivalent to the BD239A-S. Both devices share identical voltage ratings (60 V), power dissipation (2 W), saturation voltage characteristics (700mV @ 1A), and DC current gain specifications (15 @ 1A, 4V). The TIP29AG is manufactured by onsemi with Active product status and ROHS3 compliance, ensuring long-term availability and regulatory conformance. Operating temperature range matches the original specification (-65°C to 150°C).

For Enhanced Performance with Minimal Circuit Modification:

The 2ST31A and TIP31A both provide 3 A collector current capability with 60 V voltage rating and 40 W power dissipation. These devices maintain the same voltage and temperature specifications as the BD239A-S while offering improved current handling. Both are ROHS3 compliant and Active status. The 2ST31A is manufactured by STMicroelectronics with higher DC current gain (100 @ 20mA, 4V), while TIP31A is from Solid State Inc. with moderate gain (25 @ 1A, 4V).

For High-Current Applications:

The D44H8 (STMicroelectronics), MJE3055T (NTE Electronics), and MJE3055TG (onsemi) support 10 A collector current with 60 V voltage rating and significantly higher power dissipation (50-75 W). These devices are suitable for applications requiring substantial current margins or thermal headroom. All three maintain ROHS3 compliance and Active status. The MJE3055TG offers the advantage of onsemi manufacturing with established supply chain presence.

For Voltage-Enhanced Applications:

The 2N6292G provides 70 V collector-emitter breakdown voltage with 7 A current capability, suitable for circuits requiring higher voltage margins while maintaining 60 V nominal operation. This device is manufactured by onsemi with Active status and ROHS3 compliance.

Product Status Considerations:

The TIP41AG is classified as Last Time Buy, indicating limited future availability. While electrically suitable with 6 A capability and 60 V rating, long-term procurement should prioritize alternatives with Active status for new designs.

Frequently Asked Questions (FAQ)

Q: Can the TIP29AG be used as a direct replacement for the BD239A-S?

A: Yes. The TIP29AG matches all critical electrical parameters: 60 V voltage rating, 2 W power dissipation, 700mV saturation voltage at 1A, and 15 DC current gain at 1A, 4V. Both devices use TO-220-3 through-hole packaging. The TIP29AG is manufactured by onsemi with Active product status, ensuring availability and ROHS3 compliance.

Q: What is the difference between the 2ST31A and TIP31A?

A: Both devices share identical electrical ratings (60 V, 3 A, 40 W) and package configuration. The primary difference is manufacturer: 2ST31A is from STMicroelectronics with DC current gain of 100 @ 20mA, 4V, while TIP31A is from Solid State Inc. with DC current gain of 25 @ 1A, 4V. Selection depends on circuit bias requirements and preferred supplier.

Q: Can I use the D44H8 or MJE3055T in place of the BD239A-S?

A: Yes, with circuit verification. Both devices maintain 60 V voltage rating and TO-220-3 packaging. However, they provide 10 A collector current and 50-75 W power dissipation compared to the BD239A-S specifications of 2 A and 2 W. These higher ratings provide performance margin but require confirmation that circuit design accommodates the different saturation voltage characteristics (1V or 8V at rated current versus 700mV).

Q: Are all substitute parts ROHS3 compliant?

A: All listed substitute parts are ROHS3 compliant, matching the regulatory status of the BD239A-S. This ensures compatibility with modern manufacturing and environmental requirements.

Q: What is the operating temperature range for substitute parts?

A: Most substitute parts operate from -65°C to 150°C, matching the BD239A-S specification. The MJE3055T and MJE3055TG operate from -55°C to 150°C, providing a slightly reduced low-temperature range. For applications requiring -65°C operation, select alternatives with the full -65°C to 150°C range.

Q: Why do some substitute parts have higher power ratings than the BD239A-S?

A: Higher power ratings reflect improved thermal design and larger die geometry in modern manufacturing. Parts like the D44H8 (50 W) and MJE3055T (75 W) can dissipate more heat while maintaining the same 60 V voltage rating. These devices are suitable for applications requiring higher current or thermal margin, but circuit design must account for different electrical characteristics at rated current.

Q: Is the 2N6292G with 70 V rating suitable for 60 V circuits?

A: Yes. The 2N6292G is rated for 70 V collector-emitter breakdown, which exceeds the 60 V requirement of the BD239A-S. This provides additional voltage margin in circuits operating at 60 V nominal. The device is suitable for direct substitution in 60 V applications.

Q: What should I consider when selecting between multiple substitute options?

A: Selection criteria include: (1) Current requirement - match or exceed the circuit's maximum collector current; (2) Power dissipation - ensure adequate thermal design for the device's power rating; (3) Saturation voltage - verify circuit design accommodates the substitute's Vce(sat) characteristics; (4) Product status - prefer Active status for long-term availability; (5) Manufacturer preference - consider established supply chain relationships; (6) Temperature range - confirm the operating temperature matches application requirements.

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