Thyristors - DIACs, SIDACs

Part Number	Description / PDF	Quantity
K3601G Wickmann / Littelfuse	SIDAC 340-380V 1A DO15	0
K2201GL Wickmann / Littelfuse	SIDAC MP 200-230V H.V. DO15	0
K2500EH70RP2 Wickmann / Littelfuse	SIDAC 240-280V 1A TO92	0
K2500G Wickmann / Littelfuse	SIDAC 240-280V 1A DO15	8454
K3002GRP Wickmann / Littelfuse	SIDAC 270-330V 1A DO15	51
K1100S1URP Wickmann / Littelfuse	SIDAC 104-118V 1A UNI DO-214AC	0
K1300E70RP2 Wickmann / Littelfuse	SIDAC 120-138V 1A TO92	0
K1500GAP Wickmann / Littelfuse	SIDAC 140-170V 1A DO15	0
K2000E70RP3 Wickmann / Littelfuse	SIDAC 190-215V 1A TO92	0
K1400GURP Wickmann / Littelfuse	SIDAC 130-146V 1A UNI DO-15	0
K1050SRP Wickmann / Littelfuse	SIDAC 95-113V 1A DO214	0
K1300GRP Wickmann / Littelfuse	SIDAC 120-138V 1A DO15	0
K1100GURP Wickmann / Littelfuse	SIDAC 104-118V 1A UNI DO-15	0
K2500EH70RP3 Wickmann / Littelfuse	SIDAC 240-280V 1A TO92	0
K2400GH Wickmann / Littelfuse	SIDAC 220-250V 1A DO15	0
K2500EH70AP Wickmann / Littelfuse	SIDAC 240-280V 1A TO92	0
K2200GHU Wickmann / Littelfuse	SIDAC 205-230V 1A DO15	0
K1050G Wickmann / Littelfuse	SIDAC 95-113V 1A DO15	1000
K1400G Wickmann / Littelfuse	SIDAC 130-146V 1A DO15	0
K2500E70AP Wickmann / Littelfuse	SIDAC 240-280V 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:

Match VBO to TRIAC gate requirements
Verify current ratings with load characteristics
Choose packaging based on thermal needs
Consider dv/dt ratings for noisy environments
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.