5th EE Semiconductors: Thyristors

A Silicon Controlled Rectifier is a _______ semiconductor device.

The SCR has three connecting terminals. These are the ________.

(type answer as a list with spaces after the commas

e.g. cat, mouse, horse)

In its on state, current flows from the Cathode to the Anode of an SCR

• True

• False

In its on state, current flows from the Anode to the Cathode of an SCR.

• True

• False

The SCR has three modes of operation. These are

• Forward conducting

• Reverse Conducting

• Forward Blocking

• Reverse Blocking

The gate of Thyristors is usually connected to resistors. The reason for this is

• to ensure the gate is always on

• to limit the gate current

• to get a spike in the gate signal

• to filter out the noise in a circuit.

An SCR can be switch "on" by exceeding the forward breakover voltage from Anode to Cathode.

• True

• False

The SCR in this circuit has a maximum gate current rating of 50 mA. The gate-cathode voltage drop is 1V, this means there should be a ________ resistance to protect the gate.

Which of the following are advantages of using Thyristors?

• They can handle large current, voltage and power

• They can be used for AC and DC applications

• The control process is simple

• They are expensive

A Triode for AC can be used to control _________ of an AC input signal.