DB3-TP DIAC Thyristor Equivalent & Substitute Parts

Part Overview

The DB3-TP is a DIAC thyristor manufactured by Micro Commercial Co, rated for 28–36V breakover voltage with 2A peak output current in DO-35 axial packaging. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. DIAC thyristors function as bidirectional trigger devices in AC applications, particularly in phase control and triac triggering circuits. Substitution requires matching breakover voltage range, current ratings, and package specifications to maintain circuit functionality.

Substiute Parts

DB3-TP

Micro Commercial CoIn Stock: 1116DB3-TP Datasheet

Current PartRFQ

DB3

Fairchild SemiconductorIn Stock: 770983DB3 Datasheet

SimilarRFQ

DB3TG

STMicroelectronicsIn Stock: 2484DB3TG Datasheet

SimilarRFQ

DB4

STMicroelectronicsIn Stock: 20892DB4 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of DIAC thyristors is determined by the following critical parameters:

Breakover Voltage Range: The primary selection criterion. Substitutes must operate within the same or overlapping voltage window to ensure proper trigger timing in AC circuits.

Peak Output Current: Must equal or exceed the main part specification (2 A minimum) to handle circuit load requirements.

Package Type: All candidates maintain DO-35 axial packaging, ensuring mechanical and electrical compatibility with existing PCB layouts.

Breakover Current: Secondary parameter affecting trigger sensitivity; lower values indicate faster response.

Operating Temperature Range: Must support the application's thermal environment.

Product Status & Compliance: RoHS3 compliance and REACH status ensure regulatory alignment for current manufacturing and supply chains.

Based on these criteria, substitute parts are grouped as follows:

• Direct Equivalents (28–36V range): DB3 (Fairchild Semiconductor)
• Narrow-Range Equivalent (30–34V range): DB3TG (STMicroelectronics)
• Higher-Voltage Alternative (35–45V range): DB4 (STMicroelectronics)

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (28–36V Applications)

DB3 (Fairchild Semiconductor) provides full voltage range compatibility with DB3-TP. Although both parts are obsolete, DB3 maintains ROHS3 compliance and equivalent electrical specifications. This substitution is suitable when existing circuit designs require the 28–36V breakover window.

For Narrow-Range Applications (30–34V Window)

DB3TG (STMicroelectronics) operates within a tighter voltage band (30–34V) and features active product status, ensuring long-term supply availability. The lower breakover current (15 µA) provides faster trigger response. This part is preferred for new designs or when procurement of obsolete parts becomes constrained. Operating temperature extends to 125°C, supporting higher thermal environments than the main part.

For Higher-Voltage Circuits (35–45V Applications)

DB4 (STMicroelectronics) is specified for 35–45V breakover voltage and is suitable only when circuit design permits operation in this higher voltage range. Active product status and extended temperature rating (–40°C to 125°C) make this part suitable for modern applications. This substitution requires circuit validation to confirm voltage compatibility.

Compliance Considerations

All substitute parts maintain ROHS3 compliance and REACH unaffected status, meeting current regulatory requirements for electronic component manufacturing and distribution.

Frequently Asked Questions (FAQ)

Q: Can DB3 (Fairchild) directly replace DB3-TP (Micro Commercial Co)?

A: Yes. Both parts share identical breakover voltage (28–36V), peak output current (2 A), and DO-35 axial packaging. Electrical and mechanical compatibility is confirmed. Both parts are obsolete; verify long-term availability with your supplier.

Q: What is the difference between DB3TG and DB3-TP?

A: DB3TG operates within a narrower voltage range (30–34V versus 28–36V) and has lower breakover current (15 µA versus 100 µA), resulting in faster trigger response. DB3TG is active, while DB3-TP is obsolete. DB3TG supports higher operating temperature (125°C versus 110°C). Use DB3TG when the 30–34V window is acceptable and long-term supply is required.

Q: When should I use DB4 instead of DB3-TP?

A: DB4 is specified for 35–45V breakover voltage. Use DB4 only if your circuit design operates in this higher voltage range. Direct substitution of DB4 for DB3-TP in 28–36V circuits will result in improper trigger timing and circuit malfunction.

Q: Are all substitute parts available in DO-35 packaging?

A: Yes. DB3 (Fairchild), DB3TG (STMicroelectronics), and DB4 (STMicroelectronics) are all supplied in DO-35 axial packaging, ensuring mechanical compatibility with existing PCB layouts.

Q: Do substitute parts meet RoHS and REACH requirements?

A: Yes. All substitute parts (DB3, DB3TG, DB4) are ROHS3 compliant and REACH unaffected, meeting current regulatory standards for electronic component manufacturing and distribution.

Q: Which substitute part should I choose for a new design?

A: DB3TG (STMicroelectronics) is recommended for new designs. It is active (not obsolete), supports extended operating temperature (125°C), and provides reliable long-term supply. Verify that the 30–34V breakover range is compatible with your circuit requirements.