BD438STU Equivalent & Substitute Parts

Part Overview

The BD438STU is a PNP bipolar junction transistor manufactured by onsemi, rated for 45 V collector-emitter breakdown voltage and 4 A maximum collector current. The device is packaged in TO-126-3 (TO-225AA) through-hole configuration and delivers 36 W maximum power dissipation with a 3 MHz transition frequency. The BD438STU is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design support and procurement continuity.

Substiute Parts

BD438STU

onsemiIn Stock: 2109BD438STU Datasheet

Current PartRFQ

BD438S

onsemiIn Stock: 2377BD438S Datasheet

DirectRFQ

BD438G

onsemiIn Stock: 1183BD438G Datasheet

SimilarRFQ

BD438

STMicroelectronicsIn Stock: 6538BD438 Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the BD438STU is determined by matching the following critical electrical and mechanical parameters:

Electrical Parameters:

• Transistor type: PNP
• Maximum collector current: 4 A
• Maximum collector-emitter breakdown voltage: 45 V
• Maximum power dissipation: 36 W
• Transition frequency: 3 MHz

Mechanical Parameters:

• Mounting type: Through Hole
• Package compatibility: TO-126-3 or TO-225AA

Compliance Parameters:

• RoHS3 compliance
• REACH unaffected status

Substitute parts are grouped into three categories based on their relationship to the BD438STU:

Direct Manufacturer Substitutes: Parts with identical electrical specifications and the same base product number (BD438) from onsemi, differing only in packaging or product status designation.

Similar Manufacturer Variants: Parts with the same base product number and manufacturer but featuring enhanced or modified electrical characteristics (such as improved DC current gain or extended temperature range) while maintaining core voltage, current, and power ratings.

Parametric Equivalents: Parts from alternative manufacturers with identical or equivalent electrical specifications and compatible through-hole packaging, enabling functional replacement in circuit applications.

Parameter Comparison

Engineering Selection Recommendations

BD438S (onsemi): This direct substitute maintains identical electrical specifications to the BD438STU across all critical parameters. The BD438S carries Last Time Buy status, indicating limited availability. Selection of BD438S is appropriate for applications requiring exact electrical equivalence with onsemi sourcing. Bulk packaging is available.

BD438G (onsemi): This variant offers enhanced DC current gain (85 @ 500mA, 1V versus 30 @ 10mA, 5V) and extended operating temperature range (-55°C to 150°C). The BD438G is classified as Active, ensuring long-term availability. Vce saturation is slightly elevated (700mV @ 300mA, 3A). Selection of BD438G is appropriate for applications requiring improved current gain characteristics and extended temperature operation, with continued manufacturer support.

BD438 (STMicroelectronics): This parametric equivalent from STMicroelectronics matches the BD438STU electrical specifications exactly. The device is packaged in SOT-32-3 rather than TO-126-3, requiring PCB layout modification. The BD438 is classified as Active with high inventory availability (6483 Pcs). Selection is appropriate for applications where alternative manufacturer sourcing and package compatibility are acceptable, providing supply chain diversification and long-term availability assurance.

All substitute options maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory continuity.

Frequently Asked Questions (FAQ)

Q: Can BD438S directly replace BD438STU without circuit modification?

A: Yes. The BD438S maintains identical electrical specifications across collector current, breakdown voltage, power dissipation, transition frequency, and saturation characteristics. No circuit modification is required. PCB layout remains unchanged as both use TO-126-3 packaging.

Q: What is the primary difference between BD438STU and BD438G?

A: The BD438G features enhanced DC current gain (85 @ 500mA, 1V) compared to BD438STU (30 @ 10mA, 5V), and extends the operating temperature range to -55°C to 150°C. Vce saturation is slightly higher at 700mV @ 300mA, 3A. The BD438G is Active status, ensuring continued availability.

Q: Can STMicroelectronics BD438 be used as a substitute?

A: The STMicroelectronics BD438 provides identical electrical specifications but uses SOT-32-3 packaging instead of TO-126-3. PCB layout modification is required. The device is Active status with high inventory. Selection depends on design flexibility regarding package change.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. BD438S, BD438G, and STMicroelectronics BD438 are all ROHS3 compliant and REACH unaffected, maintaining regulatory equivalence with BD438STU.

Q: Which substitute offers the longest supply chain continuity?

A: BD438G (onsemi) and BD438 (STMicroelectronics) are both classified as Active. BD438G maintains onsemi sourcing with TO-126-3 packaging compatibility. STMicroelectronics BD438 provides alternative manufacturer sourcing with 6483 Pcs inventory but requires package accommodation.

Q: What is the significance of BD438S Last Time Buy status?

A: Last Time Buy designation indicates limited future availability. BD438S is appropriate for immediate procurement needs but not recommended for long-term production planning. BD438G or STMicroelectronics BD438 are preferred for sustained production requirements.

Q: Do all substitutes maintain the same through-hole mounting configuration?

A: Yes. BD438S and BD438G use TO-126-3 through-hole packaging identical to BD438STU. STMicroelectronics BD438 uses SOT-32-3 through-hole packaging, which requires PCB layout modification but maintains through-hole mounting type.