BD238STU Equivalent & Substitute Parts

Part Overview

The BD238STU is an onsemi PNP bipolar junction transistor rated for 80 V collector-emitter breakdown voltage and 2 A maximum collector current. This device is packaged in the TO-126-3 through-hole configuration and delivers 25 W maximum power dissipation with a 3 MHz transition frequency. The BD238STU is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and production continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	80	V
Current - Collector (Ic) (Max)	2	A
Power - Max	25	W
Frequency - Transition	3	MHz
Vce Saturation (Max) @ Ib, Ic	600 mV @ 100 mA, 1 A	—
DC Current Gain (hFE) (Min) @ Ic, Vce	25 @ 1 A, 2 V	—
Mounting Type	Through Hole	—
Package / Case	TO-126-3	—
Operating Temperature (Max)	150	°C

Substitute Part Grouping Explanation

Substitution of the BD238STU is determined by strict alignment of electrical and mechanical parameters. The following criteria establish valid substitute relationships:

Primary Substitution Criteria:

Transistor Type: PNP (required match)
Voltage - Collector Emitter Breakdown (Max): 80 V (required match)
Current - Collector (Ic) (Max): equal to or greater than 2 A
Power - Max: equal to or greater than 25 W
Mounting Type: Through Hole (required match)
Package / Case: TO-126-3 or compatible TO-225AA variant (required match)

Secondary Compatibility Factors:

Frequency - Transition: 2 MHz or higher
Operating Temperature: 150°C or higher maximum junction temperature
RoHS3 Compliance: required
REACH Status: Unaffected (required)

Substitute parts are grouped into two categories based on current-handling capability and power dissipation:

Category A (Current-Limited Substitutes): Parts with Ic(Max) between 1 A and 1.5 A and Power(Max) between 1.25 W and 30 W. These parts are suitable for applications where the BD238STU's 2 A current rating is not fully utilized.

Category B (Current-Enhanced Substitutes): Parts with Ic(Max) of 4 A and Power(Max) of 40 W. These parts provide increased current-handling capacity and are suitable for applications requiring higher current margins.

Parameter Comparison

Part Number	Manufacturer	Ic (Max)	Vce Breakdown (Max)	Power (Max)	Frequency (Transition)	Package	Product Status
BD238STU	onsemi	2 A	80 V	25 W	3 MHz	TO-126-3	Obsolete
2N4920G	onsemi	1 A	80 V	30 W	3 MHz	TO-126	Active
2N5195G	onsemi	4 A	80 V	40 W	2 MHz	TO-126	Active
BD140G	onsemi	1.5 A	80 V	1.25 W	—	TO-126	Active
BD180G	onsemi	1 A	80 V	30 W	3 MHz	TO-126	Active
BD140	STMicroelectronics	1.5 A	80 V	1.25 W	—	SOT-32-3	Active
BD140-16	STMicroelectronics	1.5 A	80 V	1.25 W	—	SOT-32	Active

Engineering Selection Recommendations

Direct Substitutes (Recommended Priority):

The 2N4920G and BD180G are the primary recommended substitutes for the BD238STU. Both parts are manufactured by onsemi, maintain active product status, and are available in TO-126 packaging compatible with TO-126-3 footprints. Both devices provide 30 W power dissipation and 3 MHz transition frequency matching the original specification. The 2N4920G and BD180G differ in maximum collector current (1 A versus 2 A), making them suitable for applications where the full 2 A rating of the BD238STU is not required. Both parts carry RoHS3 compliance and REACH Unaffected status.

Alternative Substitutes (Current-Enhanced Applications):

The 2N5195G provides increased current-handling capacity at 4 A maximum collector current and 40 W power dissipation. This part is manufactured by onsemi and maintains active product status. The 2N5195G is suitable for applications requiring higher current margins or where design headroom is necessary. Transition frequency is specified at 2 MHz, which meets the minimum requirement for most switching applications.

Cross-Manufacturer Substitutes (Package Consideration):

The BD140 and BD140-16 from STMicroelectronics are electrically compatible with the BD238STU in terms of voltage and current ratings. However, these parts are packaged in SOT-32-3 and SOT-32 configurations respectively, which differ from the TO-126-3 through-hole package of the original device. These substitutes are suitable only for applications where PCB layout and mechanical mounting can accommodate the alternative package geometry. Power dissipation is limited to 1.25 W, restricting use to low-power applications.

Compliance and Availability:

All recommended substitute parts maintain RoHS3 compliance and REACH Unaffected status, ensuring regulatory alignment with the original BD238STU. All substitute parts are currently in active production status, providing long-term supply continuity.

Frequently Asked Questions (FAQ)

Q: Can the 2N4920G directly replace the BD238STU in all applications?

A: The 2N4920G is electrically compatible with the BD238STU for voltage and frequency specifications. However, the 2N4920G is rated for 1 A maximum collector current compared to the BD238STU's 2 A rating. Direct substitution is valid only for applications where the actual collector current does not exceed 1 A. Circuit analysis is required to confirm current requirements.

Q: What is the difference between the onsemi and STMicroelectronics BD140 variants?

A: Both manufacturers produce BD140 devices with identical electrical specifications (1.5 A, 80 V, 1.25 W). The primary difference is packaging: onsemi supplies the BD140G in TO-126 configuration, while STMicroelectronics supplies BD140 and BD140-16 in SOT-32-3 and SOT-32 configurations respectively. Package selection depends on PCB layout and mechanical mounting requirements.

Q: Is the 2N5195G suitable for all BD238STU applications?

A: The 2N5195G provides higher current capacity (4 A) and power dissipation (40 W) than the BD238STU. This part is suitable for applications requiring increased current margins or higher power handling. The transition frequency is specified at 2 MHz, which is lower than the BD238STU's 3 MHz but remains adequate for most switching applications. Verification of frequency requirements is necessary for high-speed switching circuits.

Q: Why is the BD140G power rating (1.25 W) significantly lower than the BD238STU (25 W)?

A: The BD140G and BD238STU have different thermal and mechanical designs despite similar electrical ratings. The BD140G is optimized for lower power dissipation applications. The BD140G is not suitable for applications requiring the full 25 W power capability of the BD238STU.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed in this reference maintain RoHS3 compliance and REACH Unaffected status, ensuring regulatory alignment with the original BD238STU.

Q: What is the significance of the TO-126 versus TO-126-3 package designation?

A: TO-126 and TO-126-3 refer to the same physical package family with three leads. The "-3" designation explicitly indicates three-lead configuration. These packages are mechanically and electrically compatible for through-hole PCB mounting applications.

Q: Can the BD180G replace the BD238STU in high-frequency applications?

A: The BD180G maintains the 3 MHz transition frequency specification of the BD238STU, making it suitable for equivalent high-frequency performance. However, the BD180G is rated for 1 A maximum collector current compared to the BD238STU's 2 A. Substitution is valid only if circuit current requirements do not exceed 1 A.

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