DIAC
Sign in to savethumb|80px|Three-layer DIAC The DIAC (diode for alternating current) is a diode that conducts electrical current only after its breakover voltage, VBO, has been reached momentarily. Three, four, and five layer structures may be used. Behavior is similar to the voltage breakdown of a TRIAC without a gate terminal.
Key facts
- Electronic component.name
- DIAC
- Electronic component.caption
- DIAC
- Electronic component.type
- Passive
- Electronic component.symbol
- 100px
- Electronic component.pins
- anode 1, anode 2
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Article
6 sectionsContents
- SIDAC
- Applications
- See also
- References
- General
- External links
thumb|80px|Three-layer DIAC The DIAC (diode for alternating current) is a diode that conducts electrical current only after its breakover voltage, VBO, has been reached momentarily. Three, four, and five layer structures may be used. Behavior is similar to the voltage breakdown of a TRIAC without a gate terminal.
When breakdown occurs, internal positive feedback (impact ionization or two transistor feedback) ensures that the diode enters a region of negative dynamic resistance, leading to a sharp increase in current through the diode and a decrease in the voltage drop across it (typically full switch-on takes a few hundred nanoseconds to microseconds). The diode remains in conduction until the current through it drops below a value characteristic for the device, called the holding current, IH. Below this threshold, the diode switches back to its high-resistance, non-conducting state. This behavior is bi-directional, meaning typically the same for both directions of current.