Thyristors - DIACs, SIDACs

Image Part Number Description / PDF Quantity Rfq
ST35

ST35

Wickmann / Littelfuse

DIAC 30-40V 2A DO214

0

HT36ARP

HT36ARP

Wickmann / Littelfuse

DIAC 32-40V 2A DO35

0

K1050S

K1050S

Wickmann / Littelfuse

SIDAC 95-113V 1A DO214

0

K1200S

K1200S

Wickmann / Littelfuse

SIDAC 110-125V 1A DO214

0

ST34B

ST34B

Wickmann / Littelfuse

DIAC 32-36V 2A DO214

0

MKP3V240

MKP3V240

Sanyo Semiconductor/ON Semiconductor

SIDAC 220-250V 1A AXIAL

0

ST32RP

ST32RP

Wickmann / Littelfuse

DIAC 27-37V 2A DO214

0

K2400F1

K2400F1

Wickmann / Littelfuse

SIDAC 220-250V 1A TO92

0

K2400S

K2400S

Wickmann / Littelfuse

SIDAC 220-250V 1A DO214

0

ST40RP

ST40RP

Wickmann / Littelfuse

DIAC 35-45V 2A DO214

0

MKP1V160RL

MKP1V160RL

Sanyo Semiconductor/ON Semiconductor

SIDAC 150-170V 900MA AXIAL

0

K2200F2

K2200F2

Wickmann / Littelfuse

SIDAC 205-230V 1A TO92

0

ST32B

ST32B

Wickmann / Littelfuse

DIAC 30-34V 2A DO214

0

K1100S

K1100S

Wickmann / Littelfuse

SIDAC 104-118V 1A DO214

0

K2500F1

K2500F1

Wickmann / Littelfuse

SIDAC 240-280V 1A TO92

0

K2200F1

K2200F1

Wickmann / Littelfuse

SIDAC 205-230V 1A TO92

0

HT32B

HT32B

Wickmann / Littelfuse

DIAC 30-34V 2A DO35

0

BS08D-112

BS08D-112

Powerex, Inc.

SIDAC 7-9V 1A TO92-3

0

K2200S

K2200S

Wickmann / Littelfuse

SIDAC 205-230V 1A DO214

0

K2200F23

K2200F23

Wickmann / Littelfuse

SIDAC 205-230V 1A TO92

0

Thyristors - DIACs, SIDACs

1. Overview

DIACs (Diodes for Alternating Current) and SIDACs (Silicon Diodes for Alternating Current) are bidirectional trigger devices used primarily to control thyristor-based circuits. These three-layer semiconductor devices exhibit negative resistance characteristics and are critical in AC power control systems. They enable precise switching of high-voltage AC loads through their unique breakover voltage behavior, making them essential in lighting, motor control, and industrial automation applications.

2. Main Types and Functional Classification

Type Functionality Application Examples
DIAC Low-power bidirectional trigger diode with symmetrical breakover voltage TRIAC gate triggering in dimmer switches
SIDAC Higher current/voltage capability with precise voltage clamping Industrial motor speed controllers
Programmable DIAC Voltage-adjustable triggering through external resistors Customizable power control systems

3. Structure and Composition

DIACs/SIDACs typically consist of a four-layer (PNPN) silicon structure with two main terminals (A1/A2). The symmetrical doping profile creates a negative resistance region during reverse bias. Advanced devices incorporate:

  • Epitaxial silicon layers for precise voltage control
  • Passivation layers for voltage stability
  • Metallization patterns for thermal management
  • Plastic/ceramic packaging for environmental protection

4. Key Technical Specifications

Parameter Description Importance
Breakover Voltage (VBO) Voltage threshold for conduction (typically 20-32V) Determines triggering point
Trigger Current (IT) Minimum current to sustain conduction Impacts load compatibility
Holding Current (IH) Current level to maintain on-state Affects circuit stability
Peak Current (IPT) Maximum transient current capability Overload protection
dv/dt Voltage change rate immunity Prevents false triggering

5. Application Areas

Key industries and equipment:

  • Lighting: Smart dimming systems, LED drivers
  • Industrial: Conveyor belt controllers, heating systems
  • Consumer: Washing machine motor controls
  • Power Electronics: AC voltage regulators

Example: DIACs in phase-control dimmers trigger TRIACs at specific AC cycle points to adjust light intensity.

6. Leading Manufacturers and Products

Manufacturer Product Series Key Features
STMicroelectronics DB3 Standard DIAC with 32V VBO
ON Semiconductor SIDAC103 100V, 3A industrial SIDAC
Vishay TECC94 High surge current capability

7. Selection Guidelines

Key considerations:

  1. Match VBO to TRIAC gate requirements
  2. Verify current ratings with load characteristics
  3. Choose packaging based on thermal needs
  4. Consider dv/dt ratings for noisy environments
  5. Evaluate temperature stability for industrial applications

8. Industry Trends

Emerging developments:

  • Integration with wide-bandgap semiconductors (SiC/GaN)
  • Miniaturization for PCB space optimization
  • Improved dv/dt immunity for EV charging systems
  • Smart grid compatibility with IoT-enabled controllers

Market growth driven by energy-efficient lighting and industrial automation demands.

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