18 Questions
In which mode of operation should TRIAC not be used for high (di/dt) circuits?
Mode 1
What type of gate pulses should be used if marginal triggering capability is required in mode 2 and mode 3?
Negative gate pulses
Which mode is more sensitive in triggering compared to mode 2 and mode 3?
Mode 1
In which quadrant operation of TRIAC is the voltage at terminal MT2 positive with respect to terminal MT1?
First Quadrant
In which quadrant operation of TRIAC is the gate voltage negative with respect to terminal 1?
Second Quadrant
In which quadrant operation of TRIAC is the gate voltage negative and terminal 1 is positive with respect to terminal 2?
Third Quadrant
What is the construction of a TRIAC?
Two SCRs connected in inverse parallel with a common gate terminal.
What are the three terminals of a TRIAC?
Main terminal 1 (MT1), main terminal 2 (MT2), and gate terminal G.
Describe the operation of a TRIAC in the positively biased region.
When MT2 and gate are positive with respect to MT1, current flows through P1-N1-P2-N2.
Explain the operation of a TRIAC in the negatively biased region.
When MT2 and gate are negative with respect to MT1, current flows through P2-N1-P1-N4.
What happens when MT2 is positive but the gate is negative with respect to MT1?
Current flows through the path P1-N1-P2-N2 with P2-N3 being forward biased.
What occurs when MT2 is negative but the gate is positive with respect to MT1?
P2-N2 is forward biased, leading to current carriers being injected and the TRIAC turning on.
What is a TRIAC used for?
High power lamp switching and AC power control
What is a QUADRAC and how is it triggered?
A special thyristor combining a DIAC and a TRIAC; DIAC is the triggering device for the TRIAC
What is a GTO and how is it turned on?
Gate Turn Off Thyristor; a small positive gate current triggers it into conduction mode
How is a GTO turned off?
By a negative pulse on the gate
Why are asymmetric GTOs preferred over symmetric GTOs?
Asymmetric GTOs have lower ON state voltage drop and more stable temperature characteristics
What is the role of the n+ layer in the construction of a GTO?
To obtain high emitter efficiency
Test your knowledge on the operation modes and characteristics of a TRIAC. Learn about the sensitivity of triggering in different modes and when to use negative gate pulses. Understand the specific characteristics of TRIAC during first-quadrant operation.
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