Q.Draw the VI Characteristics of SCR.

The static V-I characteristic of an SCR has a forward blocking region, a forward conduction region (reached at the break-over voltage $V_{BO}$) and a reverse blocking region. …

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Plot $I_A$ vs $V_{AK}$: forward blocking until $V_{BO}$, then forward conduction at low voltage; reverse blocking until $V_{BR}$; higher $I_g$ reduces $V_{BO}$.

The static V-I characteristic of the SCR is drawn with anode current $I_A$ on the vertical axis and anode-to-cathode voltage $V_{AK}$ on the horizontal axis. It has three regions:

• Forward blocking (OFF) region: with the anode positive and the gate open, the middle junction $J_2$ is reverse biased, so only a small forward leakage current flows as $V_{AK}$ is increased up to the forward break-over voltage $V_{BO}$.
• Forward conduction (ON) region: at $V_{BO}$ the SCR breaks over; the voltage across it collapses to about 1 to 1.5 V and a large anode current flows, limited only by the external resistance. The device stays ON as long as the current exceeds the holding current $I_H$; the latching current $I_L$ is the minimum current needed to latch it ON. …