What is Breakover Current of an SCR?

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Editorial Team - everything PE

Jun 6, 2024

The breakover current of an SCR (Silicon-Controlled Rectifier) is the current at which the device breaks down and starts conducting heavily. This current is measured at the breakover voltage, which is the minimum forward voltage required to turn the SCR ON. The breakover current is an important parameter because it indicates the current level at which the SCR will turn on and conduct heavily once the breakover voltage is reached. This current marks the transition from the forward blocking mode to the forward conduction mode. For the reliable and safe operation of SCR-based systems, it is important to ensure that the breakover current is properly managed.

Breakover Current Calculation

The breakover current can be calculated by considering the V-I characteristics of the SCR. The breakover current is the current at which the forward voltage falls from 0.9 𝑉𝑎 to 0.1 𝑉𝑎, where 𝑉𝑎 is the initial forward blocking voltage.

Significance of Breakover Current

The breakover current is crucial in the design and operation of SCR-based systems. It ensures that the SCR operates within its safe operating range and prevents accidental turn ON due to excessive voltage. The breakover current also affects the turn-on time and the overall performance of the SCR.

Factors Influencing Breakover Current

The breakover current is influenced by various factors such as:

  • Gate Current: Higher gate currents reduce the breakover current by increasing the rate of charge injection into the gate region, allowing the SCR to turn ON faster.
  • Forward Voltage: The breakover current increases as the forward voltage increases, as the SCR requires more current to break down at higher voltages.
  • Junction Temperature: The breakover current can be affected by the junction temperature of the SCR, which can cause changes in the device's electrical characteristics.

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