HT5761A Equivalent & Substitute Parts

Part Overview

The HT5761A is a DIAC thyristor manufactured by Littelfuse Inc., rated for 30–34V breakover voltage with 2A peak output current in a DO-35 axial package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The HT5761A operates across the industrial temperature range of –40°C to 125°C and meets ROHS3 compliance requirements.

Substiute Parts

HT5761A

Littelfuse Inc.In Stock: 1013HT5761A Datasheet

Current PartRFQ

DB3

Fairchild SemiconductorIn Stock: 770983DB3 Datasheet

MFR RecommendedRFQ

DB3TG

STMicroelectronicsIn Stock: 2484DB3TG Datasheet

MFR RecommendedRFQ

DB4

STMicroelectronicsIn Stock: 20892DB4 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the HT5761A is determined by the following critical parameters:

• Voltage – Breakover Range: The substitute must operate within or encompass the 30–34V specification
• Current – Peak Output: Must support minimum 2A peak output
• Package / Case: Must be compatible with DO-35 axial package format
• Operating Temperature Range: Must support –40°C to 125°C minimum
• RoHS Compliance: Must meet ROHS3 or equivalent environmental standards

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

Group 1 – Direct Equivalents (Identical Voltage Range)

• DB3TG (STMicroelectronics): Exact voltage match (30–34V), identical current ratings, active product status

Group 2 – Voltage-Compatible Substitutes (Overlapping Range)

• DB3 (Fairchild Semiconductor): Broader voltage range (28–36V) encompasses the HT5761A specification; identical current ratings and package

Group 3 – Higher Voltage Alternative (Non-Interchangeable for Direct Replacement)

• DB4 (STMicroelectronics): Higher breakover voltage (35–45V); suitable only for applications tolerating higher trigger thresholds

Parameter Comparison

Engineering Selection Recommendations

Preferred Substitute: DB3TG (STMicroelectronics)

The DB3TG offers the highest compatibility with the HT5761A due to identical voltage breakover range (30–34V), matching breakover current (15 µA), and active product status. This part is available in Cut Tape packaging with 2,420 units in stock and carries full ROHS3 and REACH compliance certifications.

Secondary Substitute: DB3 (Fairchild Semiconductor)

The DB3 provides functional compatibility through its overlapping voltage range (28–36V) and identical peak output current (2A). Although obsolete, it maintains 770,958 units in inventory. The higher breakover current specification (50 µA versus 15 µA) represents a minor operational difference that does not preclude substitution in most applications.

Alternative Substitute: DB4 (STMicroelectronics)

The DB4 is suitable only for applications where a higher trigger threshold (35–45V) is acceptable. This part is active and widely available (20,830 units in stock) but is not a direct replacement due to its elevated voltage specification.

Frequently Asked Questions (FAQ)

Q: Can DB3TG be used as a direct replacement for HT5761A?

A: Yes. The DB3TG matches the HT5761A across all critical parameters: voltage breakover (30–34V), breakover current (15 µA), peak output current (2A), operating temperature range (–40°C to 125°C), and DO-35 package format. The DB3TG is active and fully compliant with ROHS3 and REACH standards.

Q: What is the difference between DB3 and DB3TG?

A: Both parts share the same base product number (DB3) and are manufactured by different suppliers (Fairchild and STMicroelectronics, respectively). The DB3TG is the active variant with identical voltage and current specifications to the HT5761A. The DB3 (Fairchild) has a broader voltage range (28–36V) and higher breakover current (50 µA).

Q: Why is DB4 listed as a substitute if it has a different voltage range?

A: The DB4 is included as an alternative for applications where a higher breakover voltage (35–45V) is functionally acceptable. It is not a direct replacement but may serve in designs with flexible trigger threshold requirements.

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

A: Yes. All listed substitutes (DB3, DB3TG, and DB4) are specified in DO-204AH, DO-35, axial package format, ensuring mechanical and electrical compatibility with existing PCB layouts.

Q: Do the substitute parts meet the same compliance standards as the HT5761A?

A: Yes. All substitute parts are ROHS3 compliant. The DB3TG and DB4 additionally carry REACH Unaffected certification, exceeding the compliance profile of the obsolete HT5761A.