BD438-BP Equivalent & Substitute Parts Reference

Part Overview

The BD438-BP is a PNP bipolar junction transistor manufactured by Micro Commercial Co, rated for 45V collector-emitter breakdown voltage and 4A maximum collector current. This component is classified as obsolete, necessitating identification of equivalent alternatives for ongoing design requirements and production continuity. Substitute parts must maintain electrical compatibility across critical parameters including voltage rating, current capacity, and thermal characteristics while accommodating different package configurations.

Substiute Parts

BD438-BP

Micro Commercial CoIn Stock: 933BD438-BP Datasheet

Current PartRFQ

BD438

STMicroelectronicsIn Stock: 6538BD438 Datasheet

DirectRFQ

KSB1151YS

Fairchild SemiconductorIn Stock: 2634KSB1151YS Datasheet

SimilarRFQ

KSB1151YSTU

Fairchild SemiconductorIn Stock: 2443KSB1151YSTU Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the BD438-BP are classified into two categories based on electrical parameter alignment:

Direct Equivalent (BD438 by STMicroelectronics): This part maintains identical maximum collector current (4A) and collector-emitter breakdown voltage (45V) specifications. The saturation voltage and transition frequency match the original part exactly. Although power dissipation capability differs (36W versus 1.25W), this represents an enhancement rather than a limitation. The part is available in active product status with higher inventory levels.

Similar Substitutes (KSB1151YS and KSB1151YSTU by Fairchild Semiconductor): These parts exceed the original specifications in collector current (5A versus 4A) and collector-emitter breakdown voltage (60V versus 45V). Both maintain PNP transistor type and through-hole mounting configuration. The saturation voltage is superior (300mV versus 600mV), and DC current gain is significantly higher. These parts are suitable for applications where the original BD438-BP specifications represent minimum requirements rather than exact design constraints.

Key Parameters Determining Substitution:

• Transistor Type: PNP (mandatory match)
• Mounting Type: Through Hole (mandatory match)
• Collector Current: Minimum 4A required
• Collector-Emitter Breakdown Voltage: Minimum 45V required
• Operating Temperature Range: Minimum -55°C to 150°C required
• RoHS Compliance: ROHS3 Compliant (mandatory match)

Parameter Comparison

Engineering Selection Recommendations

BD438 by STMicroelectronics is the primary substitute for the obsolete BD438-BP. This part is electrically identical across all critical parameters and maintains active product status with established supply chain availability. The higher power dissipation rating (36W versus 1.25W) provides additional thermal margin without affecting circuit operation. ROHS3 compliance and MSL-1 rating ensure compatibility with modern manufacturing processes and storage requirements.

KSB1151YS and KSB1151YSTU by Fairchild Semiconductor are suitable alternatives when design specifications permit operation at higher voltage and current ratings. Both parts exceed the minimum requirements of the BD438-BP across collector current and breakdown voltage parameters. The superior saturation voltage characteristics (300mV versus 600mV) result in reduced power dissipation during saturation operation. These parts are available in active product status with adequate inventory levels. RoHS compliance status for these alternatives is not specified in available documentation.

Selection between the direct equivalent (BD438) and similar substitutes (KSB1151 series) depends on design margin requirements and compliance documentation needs. The BD438 provides exact electrical matching with confirmed ROHS3 compliance. The KSB1151 series provides enhanced performance specifications suitable for applications requiring higher current or voltage headroom.

Frequently Asked Questions (FAQ)

Q: Can the BD438 by STMicroelectronics be used as a direct replacement for the BD438-BP?

A: Yes. The BD438 by STMicroelectronics maintains identical electrical specifications for collector current (4A), collector-emitter breakdown voltage (45V), saturation voltage (600mV @ 200mA, 2A), and transition frequency (3MHz). Both parts are rated for through-hole mounting in TO-126-3 package configuration. The STMicroelectronics version is in active product status with higher inventory availability.

Q: What are the differences between the KSB1151YS and KSB1151YSTU parts?

A: Both KSB1151YS and KSB1151YSTU are PNP transistors with identical maximum ratings: 5A collector current and 60V collector-emitter breakdown voltage. The primary difference is DC current gain specification: KSB1151YS specifies 100 @ 2A, 1V while KSB1151YSTU specifies 160 @ 2A, 1V. Both parts are mounted in TO-126-3 package configuration and are available in active product status.

Q: Are the KSB1151 series parts suitable substitutes if my design uses the full 4A rating of the BD438-BP?

A: Yes. The KSB1151 series parts are rated for 5A maximum collector current, exceeding the 4A requirement of the BD438-BP. The 60V collector-emitter breakdown voltage also exceeds the 45V specification. These parts operate within their specifications at the BD438-BP current levels and provide additional design margin.

Q: What is the impact of different saturation voltage specifications between the BD438-BP and substitute parts?

A: The BD438-BP specifies 600mV saturation voltage at 200mA base current and 2A collector current. The KSB1151 series specifies 300mV under identical conditions. Lower saturation voltage reduces power dissipation during transistor saturation operation. The BD438 by STMicroelectronics maintains the 600mV specification, matching the original part exactly.

Q: Are all substitute parts available in the same package configuration as the BD438-BP?

A: All substitute parts listed are available in TO-126-3 package configuration, matching the original BD438-BP mounting type. The BD438 by STMicroelectronics is supplied in SOT-32-3 package format, which is electrically equivalent but may require PCB layout verification for mechanical fit.

Q: What compliance certifications apply to each substitute part?

A: The BD438 by STMicroelectronics is ROHS3 compliant with MSL-1 rating and REACH unaffected status. The KSB1151YS and KSB1151YSTU parts are listed as active products; however, specific RoHS compliance and REACH status documentation is not provided in the available specifications. Compliance verification with component suppliers is required for applications with regulatory requirements.

Q: Can I use the KSB1151 series parts in applications designed for the BD438-BP without circuit modifications?

A: The KSB1151 series parts exceed the electrical specifications of the BD438-BP across collector current (5A versus 4A) and breakdown voltage (60V versus 45V). These parts are electrically compatible with circuits designed for the BD438-BP. However, the higher DC current gain (100-160 versus 40) may affect base drive requirements in circuits with fixed base current. Circuit verification is necessary for applications with tight base current control specifications.