DB3-AP Equivalent & Substitute Parts

Part Overview

The DB3-AP is a bidirectional thyristor (DIAC) manufactured by Micro Commercial Co, designed for applications requiring breakover voltage in the 28–36V range. This component is classified as obsolete, making equivalent substitutes necessary for ongoing production and maintenance applications. The DB3-AP operates across a wide temperature range (-40°C to 110°C) and is packaged in the DO-35 axial format, a standard configuration for discrete thyristor devices.

Substiute Parts

DB3-AP

Micro Commercial CoIn Stock: 730DB3-AP Datasheet

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DB4

STMicroelectronicsIn Stock: 20892DB4 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the DB3-AP is determined by the following critical parameters:

• Package Compatibility: Both the main part and substitute must use the DO-35 axial package format to ensure mechanical and electrical fit in existing PCB layouts and through-hole designs.
• Breakover Voltage Range: The DB3-AP operates at 28–36V. Substitute parts must have breakover voltage specifications that align with or exceed the application's voltage requirements without introducing excessive overvoltage conditions.
• Peak Output Current: The DB3-AP supports 2 A peak output current. Substitutes must maintain this current rating to ensure adequate power handling in the target circuit.
• Temperature Operating Range: The DB3-AP functions from -40°C to 110°C. Substitutes with equal or wider temperature ranges are acceptable for equivalent operation.
• Regulatory Compliance: Both the main part and substitutes must maintain ROHS3 compliance and equivalent moisture sensitivity ratings to meet manufacturing and environmental standards.

The DB4 is identified as a suitable substitute based on these parameters, with the understanding that its higher breakover voltage range (35–45V) places it in an overlapping but distinct voltage class suitable for applications where the DB3-AP is no longer available.

Parameter Comparison

Engineering Selection Recommendations

DB4 (STMicroelectronics) is the identified substitute for the DB3-AP. Selection of the DB4 is based on the following engineering criteria:

• Product Status: The DB4 maintains active product status with STMicroelectronics, ensuring ongoing availability and supply chain continuity compared to the obsolete DB3-AP.
• Package Compatibility: Both components use the DO-35 axial package, enabling direct mechanical substitution in existing designs without PCB layout modifications.
• Electrical Equivalence: The DB4 maintains the 2 A peak output current specification and operates across a comparable temperature range (-40°C to 125°C), which exceeds the DB3-AP's range.
• Regulatory Compliance: The DB4 is ROHS3 compliant with MSL 1 rating, matching the environmental and manufacturing standards of the DB3-AP.
• Voltage Consideration: The DB4's breakover voltage range (35–45V) overlaps with the upper portion of the DB3-AP range (28–36V). Applications designed for the DB3-AP at voltages between 35–36V will operate within the DB4's specification. Applications requiring operation below 35V may require circuit evaluation to confirm compatibility.

Frequently Asked Questions (FAQ)

Q: Can the DB4 directly replace the DB3-AP in all applications?

A: The DB4 is mechanically and electrically compatible in terms of package format and peak current rating. However, the DB4's breakover voltage range (35–45V) is higher than the DB3-AP (28–36V). Direct substitution is suitable for applications operating at voltages within the overlapping range (35–36V). Applications requiring breakover below 35V should be evaluated for circuit compatibility.

Q: What is the significance of the different breakover voltage ranges?

A: Breakover voltage determines the threshold at which the DIAC conducts. The DB3-AP triggers at 28–36V, while the DB4 triggers at 35–45V. In circuits designed for the lower voltage range, the DB4 may not trigger at the intended voltage point, potentially affecting circuit performance.

Q: Are the package formats identical between DB3-AP and DB4?

A: Yes. Both components use the DO-35 axial package (DO-204AH), ensuring identical mechanical fit and pinout compatibility for through-hole PCB applications.

Q: What is the difference in breakover current between these parts?

A: The DB3-AP has a breakover current of 100 µA, while the DB4 has 50 µA. This parameter defines the current level at which breakover occurs. The lower breakover current of the DB4 may result in earlier triggering under low-current conditions.

Q: Are both parts RoHS compliant?

A: Yes. Both the DB3-AP and DB4 are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity ratings, meeting current environmental and manufacturing standards.

Q: Why is the DB3-AP listed as obsolete?

A: The DB3-AP is no longer in active production by Micro Commercial Co. The DB4 from STMicroelectronics serves as the active equivalent, ensuring continued availability for new designs and production requirements.