SBS Diode: Silicon Bilateral Switch (SBS) Quiz and Flashcards

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the number of terminals in an SCR?

3 (correct)

What type of switches are TRIACs and DIACs considered as?

Unilateral Switches

Bi-directional Switches

Tri-state Switches

Bilateral Switches (correct)

How can a TRIAC be turned ON?

By a pulse of gate current (correct)

By applying a positive main terminal voltage

By applying a breakover voltage

By applying a negative main terminal voltage

What is the main difference between an SCR and a TRIAC?

Direction of current conduction Signup and view all the answers

What is the process of triggering a TRIAC when biased with an external voltage more positive on 𝐴' compared to 𝐴''?

Sending gate current from gate to 𝐴'' Signup and view all the answers

What is the analogy between Shockley Diode and DIAC, and SCR and TRIAC?

Shockley Diode → DIAC; SCR → TRIAC Signup and view all the answers

What is the advantage of using SBS to trigger a TRIAC over using a DIAC?

It eliminates the hysteresis or flash-on effect. Signup and view all the answers

What is the purpose of 𝐶# in the flash-on effect scenario?

To charge and discharge in alternate directions during the entire positive and negative half of the input signal. Signup and view all the answers

What happens to the charge of 𝐶# when the TRIAC is ON?

It stops charging. Signup and view all the answers

Why does the light of the lamp become brighter during the succeeding half cycles?

The TRIAC is triggered earlier during the succeeding half cycles. Signup and view all the answers

What is the role of the external Zener diode in the SBS characteristic curve?

It provides a fixed voltage reference. Signup and view all the answers

What type of device is the SBS?

A type of silicon bilateral switch. Signup and view all the answers

What is the condition for the effective period of V!(t) in a TRIAC Phase-Control Circuit?

𝜋 Signup and view all the answers

What is the purpose of the gate terminal in a Silicon Bilateral Switch (SBS)?

To alter its breakover voltage in one direction Signup and view all the answers

What is the typical rating for the breakover voltage (VQP) of a Silicon Bilateral Switch (SBS)?

± 8 V Signup and view all the answers

What happens when the current through the anodes of a Silicon Bilateral Switch (SBS) falls below the holding current (IOP)?

It stops conducting until the next trigger Signup and view all the answers

What is the characteristic of a TRIAC that allows it to conduct in both directions?

It is a bilateral breakover device Signup and view all the answers

What is the purpose of a DIAC in a TRIAC Phase-Control Circuit?

To trigger the TRIAC gate Signup and view all the answers

Study Notes

Silicon Bilateral Switch (SBS)

A bilateral breakover device, similar to a DIAC
Conducts until the current through its anodes falls below the holding current (𝐼OP)
Gate terminal can alter breakover voltage in one direction
Popular in low-voltage trigger circuits with a typical 𝑉QP rating of ± 8 V

SBS Characteristic Curve (Floating Gate)

No description provided

SBS Characteristic Curve (With External Zener Diode)

No description provided

Applications of SBS

Can be used to trigger a TRIAC, eliminating hysteresis or flash-on effect encountered with DIACs

Flash-On Effect

Occurs when a DIAC is used to trigger a TRIAC
Causes the TRIAC to turn ON earlier during succeeding half cycles, resulting in a brighter lamp light
Caused by the charge of 𝐶# taking longer to charge to a certain value in the other direction

TRIAC Phase-Control Circuit

𝛼 and 𝜋+𝛼 waveforms are used to analyze the circuit
The effective period of 𝑉!& (𝑡) is 𝜋, resulting in a load RMS voltage of 𝑉!,'()
The power delivered to the load is 𝑃!-.= 𝑅!

Sample Problems

Sample Problem 1: Find the firing delay angle, 𝑉G,IJK, 𝑉G,LMN, 𝐼G,IJK, and power dissipated by the load
Sample Problem 2: Find the firing delay angle, 𝑉G,IJK, 𝑉G,LMN, 𝐼G,IJK, and power dissipated by the load

Silicon Controlled Rectifier (SCR)

A 4-layer device with three terminals: Anode, Cathode, and Gate
Simplified structure and schematic symbol shown

SCR Characteristic Curve

𝐼!= 0 for various values of 𝐼!

DIAC Characteristic Curve

No description provided

Triode for AC (TRIAC)

Essentially a DIAC with a gate terminal
Can be turned ON by a pulse of gate current
Does not require breakover voltage for initial conduction
Can conduct current in either direction, depending on main terminal voltage polarity
Considered a "Bilateral Switch"

TRIAC Construction and Schematic Symbol

No description provided

TRIAC Characteristic Curve

No description provided

TRIAC Equivalent Circuit

No description provided

Comparison: DIAC and TRIAC

Analogy: Shockley Diode → DIAC; SCR → TRIAC
Compared in terms of construction, schematic symbol, and characteristic curve

TRIAC Triggering

Triggered by current from the gate to 𝐴# when biased more positive on 𝐴" than 𝐴#
Triggered by sending gate current from 𝐴# to gate when biased more positive on 𝐴# than 𝐴"

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Learn about the characteristics and applications of Silicon Bilateral Switch (SBS) including its use in triggering TRIAC, eliminating hysteresis and flash-on effect.

JSM 2020: Silicon Bilateral Switch (SBS) and TRIAC Applications