HT32ARP DIAC Thyristor Equivalent & Substitute Parts

Part Overview

The HT32ARP 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 support. DIAC thyristors are used in AC switching applications, particularly in triac trigger circuits and phase control applications. The HT32ARP's electrical characteristics define the scope of compatible alternatives.

Substiute Parts

HT32ARP

Littelfuse Inc.In Stock: 962HT32ARP 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 of DIAC thyristors is determined by three critical parameters: breakover voltage range, peak output current rating, and package type. All substitute parts must maintain the same DO-35 axial package and 2A peak output current specification. Breakover voltage tolerance is the primary differentiator.

The HT32ARP operates within a 28–36V breakover window. Substitute parts are grouped as follows:

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

• DB3 (Fairchild Semiconductor): 28–36V breakover, 50 µA breakover current
• DB3TG (STMicroelectronics): 30–34V breakover, 15 µA breakover current (narrower range, subset of HT32ARP specification)

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

• DB4 (STMicroelectronics): 35–45V breakover, 50 µA breakover current

DB3 and DB3TG are primary substitutes for the HT32ARP due to overlapping or contained voltage specifications. DB4 operates at a higher voltage threshold and is suitable only for applications requiring 35–45V triggering.

Parameter Comparison

Engineering Selection Recommendations

For 28–36V Applications: DB3TG (STMicroelectronics) is the preferred substitute. It maintains the 15 µA breakover current specification matching the HT32ARP, operates within a contained voltage range (30–34V) that overlaps the HT32ARP specification, and carries Active product status with ROHS3 compliance and REACH Unaffected designation. This part is currently in production and widely available.

DB3 (Fairchild Semiconductor) provides an alternative with identical voltage range (28–36V) but exhibits 50 µA breakover current, which differs from the HT32ARP specification. This part is obsolete but remains in inventory. Use DB3 only if breakover current tolerance permits the higher specification.

For 35–45V Applications: DB4 (STMicroelectronics) is suitable only for circuits designed for higher breakover voltage thresholds. It is not a direct substitute for the HT32ARP in 28–36V applications. DB4 is Active, ROHS3 compliant, and REACH Unaffected.

All substitute parts maintain identical package geometry (DO-35 axial), peak output current (2A), and operating temperature range (–40°C to 125°C).

Frequently Asked Questions (FAQ)

Q: Can DB3 directly replace HT32ARP? A: DB3 matches the 28–36V breakover voltage range and 2A peak output current. However, DB3 specifies 50 µA breakover current versus HT32ARP's 15 µA. Substitution is valid if circuit design tolerates the higher breakover current specification.

Q: Why is DB3TG recommended over DB3? A: DB3TG maintains the 15 µA breakover current specification of the HT32ARP and carries Active product status, ensuring continued availability. DB3 is obsolete. DB3TG's voltage range (30–34V) is a subset of HT32ARP (28–36V), making it suitable for applications within this narrower window.

Q: Can DB4 replace HT32ARP? A: No. DB4 operates at 35–45V breakover voltage, which is outside the HT32ARP's 28–36V specification. DB4 is intended for higher-voltage trigger applications and will not function as a direct substitute in circuits designed for 28–36V operation.

Q: Are all substitutes available in the same package? A: Yes. HT32ARP, DB3, DB3TG, and DB4 are all supplied in DO-204AH/DO-35 axial package format, ensuring mechanical and electrical compatibility in PCB layouts.

Q: What compliance certifications apply to these parts? A: All parts are ROHS3 compliant. DB3TG and DB4 carry REACH Unaffected designation, confirming regulatory compliance for EU applications. DB3 carries ROHS3 compliance.

Q: What is the difference between breakover voltage and breakover current? A: Breakover voltage is the AC voltage threshold at which the DIAC conducts. Breakover current is the leakage current flowing through the DIAC before breakover occurs. Both parameters must be considered for circuit compatibility.