Onsemi C106MG SCR: Datasheet, Pinout, and Application Circuit Guide
The ON Semiconductor C106MG is a pivotal member of the Silicon Controlled Rectifier (SCR) family, designed for efficient AC power control in a wide array of applications. This robust sensitive gate SCR is renowned for its reliability in switching and phase control circuits. This guide provides a detailed overview of its datasheet specifications, pinout configuration, and a practical application circuit.
Datasheet Overview and Key Specifications
The C106MG is a plastic-packaged SCR with a standard TO-92 outline, making it suitable for through-hole PCB mounting. Its key electrical characteristics make it ideal for low to medium power control.
Repetitive Peak Off-State Voltage (VDRM): 50 V to 400 V (The "MG" suffix often denotes a 400V variant, but always verify the specific part number).
On-State Current (IT(RMS)): 4 A average forward current.
Gate Trigger Current (IGT): A remarkably low 200 µA (max), classifying it as a highly sensitive gate device. This allows it to be triggered directly by high-impedance sources like logic circuits or microcontrollers (often with a small buffer).
Gate Trigger Voltage (VGT): 0.8 V (max).
On-State Voltage (VT): 1.6 V (max) at IT = 3.5 A, indicating low conduction losses.
Operating Junction Temperature (TJ): -40°C to +110°C.
These specifications highlight the C106MG's core strength: controlling significant amounts of AC power (e.g., in motor drives, light dimmers, or heater controllers) with a very small gate signal.
Pinout Configuration
The pinout for the TO-92 packaged C106MG is standard for many thyristors. When viewing the component from the front (the side with the part number printed on it), the pins are identified as follows from left to right:
1. Anode (A): This is the main power terminal. It is the positive terminal in the circuit being controlled.
2. Gate (G): This is the control terminal. Applying a brief positive pulse relative to the cathode triggers the device into conduction.
3. Cathode (K): This is the common terminal for both the main power circuit and the gate trigger circuit.
Important: Always consult the manufacturer's datasheet for the exact mechanical drawing to avoid misidentification, as pinouts can sometimes differ between manufacturers.
Application Circuit Guide: AC Lamp Dimmer
A classic application for the C106MG is a simple AC phase-control dimmer circuit for incandescent lamps or controlling a universal motor's speed.
Circuit Operation:
The circuit consists of the C106MG SCR, a DIAC (e.g., DB3), a variable resistor (potentiometer), a fixed resistor, and a capacitor.
1. During each half-cycle of the AC input voltage, the capacitor (C1) charges through the variable resistor (Rvariable) and the fixed resistor (Rfixed).
2. The charging rate is determined by the RC time constant. Adjusting the potentiometer changes this rate.
3. When the voltage across the capacitor exceeds the breakover voltage of the DIAC (typically around 30V), the DIAC rapidly switches into conduction.
4. This sudden current discharge from the capacitor through the DIAC injects a sharp current pulse into the gate (G) of the C106MG, triggering it ON.
5. Once triggered, the SCR latches on for the remainder of that AC half-cycle, allowing current to flow through the lamp until the current drops below its holding current (IH) at the next zero-crossing point.
6. By adjusting the potentiometer, you control the point in the AC phase at which the SCR is triggered. This varies the amount of power delivered to the load, thereby dimming the lamp or reducing the motor speed.
Protection Considerations:
For a robust design, consider adding a small inductor in series with the load to suppress switching noise (EMI) and a snubber network (a resistor and capacitor in series) across the SCR to protect it from voltage transients.
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ICGOODFIND: The onsemi C106MG is a highly versatile and sensitive gate SCR, offering a perfect balance of efficient power control, ease of triggering, and robust performance. Its standard TO-92 package and well-defined characteristics make it an excellent choice for hobbyists and engineers designing cost-effective phase control, switching, and overload protection circuits in consumer and industrial electronics.
Keywords: SCR, Phase Control, Sensitive Gate, Thyristor, AC Dimmer
