MOS-controlled thyristor (MCT) terminals How many external leads does a typical MOS-controlled thyristor provide?

Introduction / Context:
The MOS-controlled thyristor (MCT) integrates MOS-gated control with a thyristor structure. Knowing its terminal count aids in understanding gate-driving and packaging conventions.

Given Data / Assumptions:

• Standard discrete MCT device.
• Conventional notation: anode (A), cathode (K), and gate (G).

Concept / Approach:
Like GTOs and IGBTs, MCTs expose a control terminal. Thus, three terminals are used: two power terminals (A and K) and one control terminal (G). Internally, complementary MOS structures provide turn-on and turn-off capability.

Step-by-Step Solution:
Identify power path: anode to cathode.Identify control: gate terminal for MOS-controlled action.Therefore, total external leads = 3.

Verification / Alternative check:
Datasheets show A, K, G pins; no separate auxiliary cathode is normally brought out in standard packages.

Why Other Options Are Wrong:

• 2 leads would imply uncontrolled device (no gate).
• 4 or more leads are not typical for MCTs.
• “2 or 3” is ambiguous; standard is 3.

Common Pitfalls:

• Confusing MCT with TRIAC (three terminals but AC bidirectional control).

Final Answer:
3