HT5761RP DIAC Thyristor Equivalent & Substitute Parts

Part Overview

The HT5761RP is a DIAC (Diode for Alternating Current) thyristor manufactured by Littelfuse Inc., rated for 28–36V breakover voltage with 2A peak output current in a DO-35 axial package. This component is classified as obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements. The HT5761RP serves as a triggering device in AC control circuits, particularly in triac-based applications requiring precise voltage-triggered switching.

Substiute Parts

HT5761RP

Littelfuse Inc.In Stock: 853HT5761RP 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 HT5761RP is determined by the following critical parameters:

Primary Compatibility Criteria:

• Package type: DO-204AH / DO-35 axial configuration (mechanical and electrical interface)
• Current - Peak Output: 2 A (functional current handling requirement)
• Operating Temperature Range: -40°C ~ 125°C (thermal operating envelope)
• RoHS3 Compliance and MSL rating (regulatory and manufacturing compatibility)

Secondary Consideration:

• Voltage - Breakover range overlap or functional equivalence within application tolerance

The substitute parts DB3, DB3TG, and DB4 all meet the primary compatibility criteria. DB3 and DB3TG operate within or overlap the 28–36V breakover range of the HT5761RP. DB4 operates at a higher 35–45V range and is suitable only for applications requiring higher trigger voltage thresholds.

Parameter Comparison

Engineering Selection Recommendations

DB3TG (STMicroelectronics) – Preferred Substitute

DB3TG is the recommended primary substitute for HT5761RP applications. It maintains identical breakover current (15 µA), matching the original part's trigger sensitivity. The breakover voltage range (30–34V) is narrower but fully contained within the HT5761RP specification (28–36V), ensuring functional compatibility. DB3TG carries Active product status with ROHS3 compliance and unlimited MSL rating, providing long-term availability and manufacturing reliability.

DB3 (Fairchild Semiconductor) – Secondary Substitute

DB3 provides full voltage range compatibility (28–36V) with the HT5761RP. However, its breakover current specification (50 µA) is higher than the original part (15 µA), resulting in reduced trigger sensitivity. DB3 is classified as Obsolete, limiting its suitability for new production designs despite current inventory availability.

DB4 (STMicroelectronics) – Voltage-Specific Applications Only

DB4 is suitable only for applications where a higher breakover voltage threshold (35–45V) is acceptable or required. It is not a direct substitute for standard HT5761RP circuits operating in the 28–36V range. DB4 carries Active product status and full compliance certifications.

Frequently Asked Questions (FAQ)

Q: Can DB3 directly replace HT5761RP in all applications?

A: DB3 maintains the same voltage range (28–36V) and package configuration, but its breakover current (50 µA) differs from HT5761RP (15 µA). This higher trigger current may affect circuit timing and sensitivity. Verification against specific application requirements is necessary before substitution.

Q: Why is DB3TG recommended over DB3?

A: DB3TG matches the breakover current specification (15 µA) of the original HT5761RP, preserving trigger sensitivity. Additionally, DB3TG holds Active product status, ensuring continued availability and manufacturing support, whereas DB3 is Obsolete.

Q: Can DB4 be used as a substitute for HT5761RP?

A: DB4 is not a direct substitute. Its breakover voltage range (35–45V) is higher than HT5761RP (28–36V). DB4 is suitable only for circuits specifically designed for higher trigger voltage thresholds. Using DB4 in a 28–36V application will prevent proper circuit operation.

Q: Are all substitute parts available in the same DO-35 package?

A: Yes. HT5761RP, DB3, DB3TG, and DB4 are all specified in DO-204AH / DO-35 axial package configuration, ensuring mechanical and electrical interface compatibility.

Q: Do all substitute parts meet RoHS3 compliance?

A: Yes. HT5761RP, DB3, DB3TG, and DB4 are all ROHS3 Compliant with MSL rating of 1 (Unlimited), meeting current regulatory and manufacturing requirements.

Q: What is the difference between breakover voltage and breakover current?

A: Breakover voltage is the AC voltage threshold at which the DIAC triggers into conduction. Breakover current is the leakage current flowing through the device before triggering occurs. Both parameters affect circuit performance and must be considered during substitution.