Determine cathode current $I_K$ of SCR when gate current $I_G$ = 100 mA, $\alpha_1$ = 0.49, $\alpha_2$ = 0.49 and .

Determine cathode current $IK$ of SCR when gate current $IG$ = 100 mA, $α₁$ = 0.49, $α₂$ = 0.49 and .

Solved Examples · Example 4

I_K

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[!TLDR]

$I_A = 2.5$ A and $I_K = I_A + I_G = 2.6$ A.

When a positive gate current $I_G$ is injected, the two-transistor model of the SCR gives an anode current

I_A = \frac{\alpha_2 I_G + (I_{co1}+I_{co2})}{1 - (\alpha_1 + \alpha_2)}

and, because the gate current also flows out at the cathode, the cathode current is $I_K = I_A + I_G$ .

Given $I_G = 100$ mA, $\alpha_1 = \alpha_2 = 0.49$ and $(I_{co1}+I_{co2}) = 1$ mA:

$I_A = \frac{(0.49 \times 100 \times 10^{-3}) + (1 \times 10^{-3})}{1 - 0.98} = \frac{0.05}{0.02} = 2.5\ \text{A}$ …