HT5761 Equivalent & Substitute Parts

Part Overview

The HT5761 is a DIAC 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 ongoing design support and procurement. DIAC thyristors function as bidirectional trigger devices in AC applications, particularly in triac gate circuits and phase control applications. The HT5761's electrical characteristics define the scope of compatible alternatives.

Substiute Parts

HT5761

Littelfuse Inc.In Stock: 825HT5761 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 DIAC thyristors is determined by three critical parameters: breakover voltage range, peak output current rating, and physical package compatibility. The HT5761 operates within a 28–36V window with 2A peak current capacity in a DO-35 package.

Substitute parts are grouped into two categories based on breakover voltage alignment:

Category 1: Direct Voltage Range Match (28–36V)

• DB3 (Fairchild Semiconductor): 28–36V breakover, 2A peak current, DO-35 package
• DB3TG (STMicroelectronics): 30–34V breakover (subset of 28–36V range), 2A peak current, DO-35 package, Active status

Category 2: Higher Voltage Range (35–45V)

• DB4 (STMicroelectronics): 35–45V breakover, 2A peak current, DO-35 package

All substitute parts share identical peak output current (2A), operating temperature range (–40°C to 125°C), package format (DO-35), and RoHS3 compliance with the HT5761.

Parameter Comparison

Engineering Selection Recommendations

For direct replacement within the 28–36V specification: DB3TG (STMicroelectronics) is the preferred substitute. It maintains the 15 µA breakover current of the HT5761, operates within the 30–34V range (a subset of the original 28–36V window), and carries Active product status with ROHS3 compliance and REACH Unaffected designation.

For applications requiring the full 28–36V range: DB3 (Fairchild Semiconductor) provides complete voltage range coverage matching the HT5761 specification. However, DB3 is classified as obsolete, limiting long-term availability.

For applications tolerating higher breakover voltage (35–45V): DB4 (STMicroelectronics) is suitable only when circuit design permits operation at elevated trigger voltages. DB4 is Active status with ROHS3 compliance and REACH Unaffected designation.

All substitute parts maintain identical mechanical compatibility (DO-35 package), thermal operating range, and peak current capacity with the HT5761.

Frequently Asked Questions (FAQ)

Q: Can DB3TG replace HT5761 in all applications? DB3TG is compatible when the application circuit tolerates the 30–34V breakover range. The HT5761 specification extends to 28V minimum; applications requiring triggering below 30V require DB3 or verification that circuit design operates safely within the DB3TG window.

Q: What is the difference between DB3 and DB3TG? Both are DIAC thyristors with 28–36V and 30–34V breakover ranges respectively, 2A peak current, and DO-35 packaging. DB3TG is manufactured by STMicroelectronics with Active status; DB3 is Fairchild Semiconductor with Obsolete status. DB3TG has identical 15 µA breakover current to HT5761, while DB3 specifies 50 µA.

Q: Why is DB4 listed as a substitute if it has a different voltage range? DB4 is included because it shares the same package (DO-35), peak current (2A), and thermal range (–40°C to 125°C) as HT5761. It functions as a substitute only in applications where the circuit design accommodates the higher 35–45V breakover voltage specification.

Q: Are all substitutes RoHS3 compliant? Yes. HT5761, DB3, DB3TG, and DB4 are all ROHS3 Compliant. DB3TG and DB4 additionally carry REACH Unaffected designation.

Q: What is the impact of different breakover current specifications? Breakover current (15 µA vs. 50 µA) affects gate trigger sensitivity. HT5761 and DB3TG specify 15 µA; DB3 and DB4 specify 50 µA. Circuit design must accommodate the specified breakover current for reliable operation.