BD788 Equivalent & Substitute Parts

Part Overview

The BD788 is a PNP bipolar junction transistor manufactured by onsemi, rated for 60 V collector-emitter breakdown voltage and 4 A maximum collector current. The device is packaged in TO-126 through-hole configuration and is rated for 15 W maximum power dissipation with a transition frequency of 50 MHz. The BD788 is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and procurement continuity.

Substiute Parts

BD788

onsemiIn Stock: 2262BD788 Datasheet

Current PartRFQ

BD438

STMicroelectronicsIn Stock: 6538BD438 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BD788 is determined by the following critical parameters:

Mandatory Compatibility Criteria:

• Transistor polarity: PNP type required
• Collector current rating: minimum 4 A
• Collector-emitter breakdown voltage: minimum 60 V
• Mounting configuration: Through-hole package
• Pin configuration: TO-126-3 compatible pinout

Performance Considerations:

• Maximum power dissipation: 15 W or greater
• Transition frequency: 50 MHz or greater
• DC current gain (hFE): sufficient for intended bias conditions
• Operating temperature range: -65°C to 150°C or equivalent

The BD438 from STMicroelectronics meets the mandatory polarity and current requirements but operates at a reduced maximum collector-emitter breakdown voltage of 45 V, which represents a voltage derating relative to the BD788 specification.

Parameter Comparison

Engineering Selection Recommendations

BD788 (onsemi) — Obsolete Status: The BD788 is classified as obsolete and is no longer in active production. Existing inventory of 2207 pieces is available as new original stock. The device is RoHS non-compliant. Selection of the BD788 is limited to applications where existing stock is available and regulatory compliance is not a requirement.

BD438 (STMicroelectronics) — Active Alternative: The BD438 is an active product with 6483 pieces in current inventory. The device is ROHS3 compliant and REACH unaffected, meeting modern regulatory requirements. The BD438 operates at a reduced maximum collector-emitter breakdown voltage of 45 V compared to the BD788 specification of 60 V. The transition frequency of the BD438 is 3 MHz, significantly lower than the BD788 rating of 50 MHz. The BD438 is packaged in SOT-32-3 configuration rather than TO-126-3.

Selection Basis:

• For applications operating at collector-emitter voltages not exceeding 45 V and transition frequencies not exceeding 3 MHz, the BD438 provides an active, compliant alternative with superior power handling capability (36 W versus 15 W).
• For applications requiring the full 60 V rating or 50 MHz transition frequency of the BD788, alternative sources or design modification is necessary.
• Regulatory compliance requirements favor the BD438 due to ROHS3 compliance status.

Frequently Asked Questions (FAQ)

Q: Can the BD438 directly replace the BD788 in all applications?

A: No. The BD438 has a reduced maximum collector-emitter breakdown voltage of 45 V compared to the BD788 specification of 60 V. Applications operating at voltages exceeding 45 V require verification that the reduced voltage rating is acceptable. Additionally, the BD438 transition frequency is 3 MHz versus 50 MHz for the BD788, which may impact high-frequency performance.

Q: Are the BD788 and BD438 pin-compatible?

A: Both devices use TO-126-3 and SOT-32-3 package designations with compatible pinouts for PNP transistor configurations. However, the physical package dimensions differ between TO-126 and SOT-32 formats. PCB layout and mechanical mounting must be verified for compatibility.

Q: What is the significance of the BD788 being obsolete?

A: Obsolete status indicates the BD788 is no longer manufactured by onsemi. Procurement is limited to existing inventory. For new designs or long-term production requirements, selection of an active alternative such as the BD438 is necessary to ensure supply chain continuity.

Q: Does the BD438 meet regulatory compliance requirements?

A: Yes. The BD438 is ROHS3 compliant and REACH unaffected. The BD788 is RoHS non-compliant. Applications subject to RoHS or REACH regulations require use of the BD438 or equivalent compliant device.

Q: What are the key differences in electrical performance between these devices?

A: The BD788 provides higher collector-emitter breakdown voltage (60 V versus 45 V) and higher transition frequency (50 MHz versus 3 MHz). The BD438 provides higher maximum power dissipation (36 W versus 15 W). Selection depends on the specific voltage, frequency, and power requirements of the application.

Q: Can the BD438 handle the same power dissipation as the BD788?

A: The BD438 has a higher maximum power rating of 36 W compared to the BD788 rating of 15 W. The BD438 can handle greater power dissipation. However, actual power dissipation in an application depends on circuit design, bias conditions, and thermal management, not solely on device ratings.