What is Breakover Voltage of a Diac?

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Editorial Team - everything PE

Jun 6, 2024

The breakover voltage of a Diac (Diode for Alternating Current) is the minimum voltage at which the diac switches from its blocking state to its conducting state. Once this voltage threshold is reached, the diac starts conducting current in either direction. This voltage is specified for both the positive and negative directions and is crucial in determining the operating conditions of the diac in a circuit.

The breakover voltage is a specific threshold voltage level that must be reached for the diac to switch from a blocking state to a conducting state. The breakover voltage for diacs usually range from about 20 V to 40 V, depending on the specific device and its design. Diacs are bidirectional devices and hence conduct current in both directions, once the breakover voltage is exceeded. The breakover voltage is usually the same for both positive and negative voltages.

Significance of Breakover Voltage of Diac

  • Diacs are mostly used in triggering applications for Triacs (Triode for Alternating Current) and other thyristors. When the voltage across the diac reaches the breakover voltage, the diac starts to conduct, allowing current to flow and trigger the connected thyristor.
  • The breakover voltage of diac is a critical design parameter in designing circuits that involve phase control, light dimming, and motor speed control.Its exact value is specified in the product datasheet.

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