Silicon Controlled Rectifiers Quiz

<p>Light bulbs. (C)</p> Signup and view all the answers

<p>p-n-p-n switching. (C)</p> Signup and view all the answers

<p>Depletion region breakdown (A)</p> Signup and view all the answers

<p>To control the turn-on conditions (A)</p> Signup and view all the answers

<p>Forward blocking region (C)</p> Signup and view all the answers

<p>Avalanche breakdown leading to damage (D)</p> Signup and view all the answers

<p>Mode 1 (A)</p> Signup and view all the answers

<p>Junction J2 does not allow current to flow. (C)</p> Signup and view all the answers

<p>Forward Conducting Mode (A)</p> Signup and view all the answers

<p>High energy minority carriers generated by collisions. (D)</p> Signup and view all the answers

<p>A small leakage current may still be present. (A)</p> Signup and view all the answers

<p>It allows for lower voltage across the anode and cathode to trigger conduction. (B)</p> Signup and view all the answers

<p>VMT21 is positive and VG1 is negative. (B)</p> Signup and view all the answers

<p>It must exceed its break over voltage to conduct. (A)</p> Signup and view all the answers

<p>It controls the point of beginning of conduction. (A)</p> Signup and view all the answers

<p>They are less reliable compared to SCRs. (A)</p> Signup and view all the answers

<p>It switches to the off-state. (D)</p> Signup and view all the answers

<p>To limit excess current during conduction. (A)</p> Signup and view all the answers

<p>The break over voltage is equal for both forward and reverse polarities. (C)</p> Signup and view all the answers

<p>Light Triggering (A)</p> Signup and view all the answers

<p>Avalanche breakdown occurs at junction J2 (D)</p> Signup and view all the answers

<p>It can lead to thermal runaway and device damage (D)</p> Signup and view all the answers

<p>Symmetrical switching characteristics (C)</p> Signup and view all the answers

<p>High rate of rise of voltage causing a transient gate current (D)</p> Signup and view all the answers

<p>Conducts only above 30 volts (A)</p> Signup and view all the answers

<p>It causes more losses in the gate circuit (B)</p> Signup and view all the answers

<p>Junctions J1 and J3 are forward biased and J2 is reverse biased (D)</p> Signup and view all the answers

<p>Transistor 2 is in cutoff mode with zero base current (D)</p> Signup and view all the answers

<p>The current reinforces the trigger effect (A)</p> Signup and view all the answers

<p>Forward blocking mode (B)</p> Signup and view all the answers

<p>Ensures equal voltage levels for both AC cycles (C)</p> Signup and view all the answers

<p>Positive voltage applied at the gate while anode is positive (B)</p> Signup and view all the answers

<p>Gate-voltage triggering can apply non-threshold voltage. (C)</p> Signup and view all the answers

<p>Junction J2 is forward biased and J1, J3 are reverse biased (D)</p> Signup and view all the answers

<p>Voltage regulation in high power circuits (A)</p> Signup and view all the answers

<p>Minimum current needed to maintain conduction (C)</p> Signup and view all the answers

<p>$I_a = [α_2 I_g] / [1 - (α_1 + α_2)]$ (C)</p> Signup and view all the answers

A 3-terminal, 4-layer semiconductor device used for controlling high-power currents.

A unidirectional current controller; a 4-layer semiconductor device that rectifies high AC currents to DC, capable of handling high voltages.

Alternative name for a Silicon Controlled Rectifier (SCR).

Describes the structure of an SCR; made of four alternating P-type and N-type semiconductor layers.

A device that converts AC (alternating current) to DC (direct current).

The region where SCR is off, with positive anode voltage, negative cathode voltage, and an open gate.

The region where SCR turns on when forward bias voltage exceeds breakdown voltage; current increases rapidly.

The region where SCR is off with negative anode voltage, positive cathode voltage, and an open gate; a small leakage current still flows.

A 3-terminal AC switch that conducts in both directions; controlled by a gate signal. Conduction controlled by a low power signal.

TRIACs have 4 operating modes representing different voltage polarities between two terminals and gate, crucial for controlling current directions.

Mode where SCR is forward biased, but no current flows. The gate is open, and junction J2 is reverse biased, acting like a barrier.

Mode where SCR allows current to flow due to high voltage or a positive gate voltage. Junction J2 breaks down.

Mode where SCR is reverse biased, and no current flows. J1 & J3 are reverse biased, preventing current flow.

An SCR comprises four layers of alternating P and N-type semiconductor materials, creating three junctions (J1, J2, J3) and three terminals (anode, cathode, gate).

Control terminal of an SCR. Applying a positive voltage here can alter the SCR's conducting state (turn it on).

Second quadrant operation; VMT21 is positive, VG1 is negative.

Third quadrant operation; both VMT21 and VG1 are negative.

A two-terminal bidirectional switch that conducts in both directions when voltage exceeds breakover voltage. It's an uncontrolled switch.

A five-layer device made from two antiparallel SCRs without gate terminals. Has two terminals (MT1 and MT2).

DIAC turns on when the applied voltage (V) surpasses its breakover voltage (VBO).

Triacs are equipped with an external resistance that moderates the large initiation current; protecting the device during operation.

The voltage level that triggers the DIAC to pass current flowing through it.

DIACs offer symmetrical switching, reducing harmonics, have a low on-state voltage drop, and are easily switched by voltage changes, facilitating smooth power control.

DIACs are low-power devices, only conduct above 30V, and cannot block high voltages.

The primary application of a DIAC is to trigger a TRIAC. This symmetrical triggering reduces harmonics, which are problematic in AC circuits.

A TRIAC's asymmetry requires DIAC triggering to ensure symmetrical switching (both halves of the AC cycle).

This model visualizes an SCR as two transistors connected in a regenerative feedback loop, explaining its latching property.

Applying a gate triggering signal starts a regenerative process that leads to the SCR being latched into its conducting state.

The initial state where the anode is positive and the cathode is negative, preparing the SCR for triggering.

The minimum current that must flow through the SCR to maintain conduction. Below this, the SCR turns off.

The positive feedback process of an SCR, where the current flowing through the device reinforces the triggering signal, causing it to maintain conduction.

Turning ON an SCR by increasing the anode-cathode voltage to its forward break over voltage, triggering avalanche breakdown and subsequent continuous conduction.

Turning ON a light-activated SCR (LASCR) by shining light on the P-layer, injecting charge carriers and triggering conduction.

Turning ON an SCR due to increased temperature increasing reverse leakage current, leading to thermal runaway and device damage.

Turning ON an SCR by rapidly increasing voltage, producing a transient gate current which may lead to spurious triggering.

Turning ON an SCR by applying a positive voltage to the gate terminal while forward biased, injecting carriers and lowering breakdown voltage.

SCR state where the anode is positive relative to the cathode, junctions J1 and J3 are forward-biased, J2 is reverse-biased, and no current flows.

SCR state where the anode is positive relative to the cathode, and current flows from anode to cathode, junctions J1 and J3 are forward biased, and J2 is forward biased.

SCR state where the anode is negative relative to the cathode, junctions J1 and J3 are reverse-biased, J2 is forward-biased, and no current flows.

A common method for reliably turning on SCR or thyristors by applying a signal to the gate terminal in the forward blocking mode.