Professional Courses
Industry-relevant training in Business, Technology, and Design to help professionals and graduates upskill for real-world careers.
Categories
Interactive Games
Fun, engaging games to boost memory, math fluency, typing speed, and English skillsβperfect for learners of all ages.
Typing
Memory
Math
English Adventures
Knowledge
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Low-Side Switch
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Today, we are diving into the concept of low-side switches. Who can tell me what that means?
Is it when the switch is connected below the load?
Exactly! In a low-side switch, the MOSFET connects the load to ground. What might be a simple advantage of this configuration?
It's easy to drive since the control signal is referenced to ground.
Right! But remember, the load is not effectively grounded, which can lead to some operational issues. Can anyone think of an application where this might be used?
Maybe in LED drivers?
Great example! In many LED applications, low-side switching is favored. Summarizing: Low-side switches are simple, easy to control, but they might not ground the load properly.
High-Side Switch
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Let's move on to high-side switches. What differentiates them from low-side ones?
The MOSFET is placed above the load, connecting it to the positive supply instead of ground.
Exactly! But controlling a high-side switch is more complex. Why do you think that is?
Because it needs a gate voltage that is higher than the supply voltage?
Correct! This is where charge pumps or bootstrap circuits come into play to provide that necessary voltage. In what applications might high-side switches be particularly useful?
They would be handy for powering motors where the ground needs to be isolated for control.
Exactly! In summary, high-side switches allow for grounded loads but require more complex driving methods.
Half-Bridge Configuration
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Now, let's discuss half-bridge configurations. Can someone explain how this topology is set up?
It uses two MOSFETs in series to control a load connected between them.
Great job! An important point to remember about half-bridges is the risk of shoot-through. What does that mean?
Itβs when both MOSFETs turn on at the same time, creating a short circuit.
Exactly! To prevent shoot-through, we implement dead time in the switching sequence. Can anyone think of an application where you might see half-bridge configurations in use?
In motor drivers and class D amplifiers!
Exactly right! To summarize: half-bridges are versatile but require careful management of timing to avoid issues.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
In this section, we examine the three primary switching topologies used with MOSFETsβlow-side, high-side, and half-bridge. Each topology has its specific advantages, challenges, and applications in electronic circuits, especially in power management.
Detailed
Switching Topologies
Overview
This section covers the essential switching topologies that utilize MOSFETs in power electronics. Each topology has unique benefits and drawbacks impacting circuit design and performance.
6.5.1 Low-Side Switch
A low-side switch configuration connects the load to the ground. Itβs simple to drive due to straightforward control. However, the load is not directly grounded, which can present issues in certain applications.
6.5.2 High-Side Switch
In a high-side switch configuration, the load is connected to ground while the switching occurs above it. This setup requires a gate voltage greater than the supply voltage, and charge pumps or bootstrap circuits are often employed to achieve this.
6.5.3 Half-Bridge
The half-bridge configuration involves two MOSFETs controlling a common load. One potential issue is the risk of shoot-through, where both MOSFETs turn on simultaneously, creating a short circuit. Implementing dead time in the switching sequence can help prevent this.
Understanding these topologies is crucial for designing efficient power circuits optimizing performance by selecting the appropriate configuration for the specific application.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Low-Side Switch
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
VDD ββLoadββD β SββGND β Gate Driver
- Pros: Simple drive.
- Cons: Load not grounded.
Detailed Explanation
A low-side switch configuration consists of a MOSFET positioned between the load and ground. When the MOSFET turns on (conducts), it allows current to flow from the power supply (VDD) through the load and into the ground. The advantage of this setup is its simplicity, as the driving voltage directly controls the MOSFET without the need for additional complex circuitry. However, a drawback is that the load is not directly grounded when the switch is off, which can lead to issues in some applications, such as when sensing voltages or for certain types of load devices.
Examples & Analogies
Think of a water faucet connected to a water pipe. When the faucet is turned on, water flows freely through it to the sink (the load). The faucet, when closed, simply stops the flow of water. This mechanism illustrates how a low-side switch works: opening the faucet (turning on the switch) lets water (current) pass while closing it (turning off) stops the flow.
High-Side Switch
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
VDD ββD β SββLoadββGND β Gate Driver
- Challenge: Requires gate voltage > VDD (use charge pumps or bootstrap).
Detailed Explanation
In a high-side switch configuration, the MOSFET is placed between the power supply (VDD) and the load. When this switch is turned on, it connects the load directly to the supply, allowing current to flow. However, a significant challenge arises because the gate voltage required to turn on the MOSFET must be higher than the voltage at the source terminal (which is also connected to the load). This often necessitates additional mechanisms, such as charge pumps or bootstrap circuits, to boost the gate voltage sufficiently for the MOSFET to operate properly.
Examples & Analogies
Imagine you are trying to lift a rope that is tied to the ceiling (representing the load). To pull the rope up, you need to use another tool (like a ladder) to get higher up (supply a higher voltage to the gate). If you only have access to the floor level (the source voltage), itβs impossible to lift it without that extra height. This is analogous to the voltage challenge in high-side switching.
Half-Bridge Configuration
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
VDD ββQ1(D)βββQ2(S)ββGND β Load
- Dead Time: Prevents shoot-through (both FETs on).
Detailed Explanation
A half-bridge configuration consists of two MOSFETs (Q1 and Q2) connected in series between the power supply and ground, with the load connected between them. This setup allows for control over the load, enabling both directional control of current (where the load can be powered in two ways) and efficient switching performance. However, a critical aspect of this design is implementing 'dead time'βa brief pause during which both MOSFETs are off. This is crucial to prevent 'shoot-through,' a condition where both MOSFETs could be turned on simultaneously, causing a short circuit directly from the supply to ground and resulting in damage or inefficiency.
Examples & Analogies
Consider a see-saw where two people should not push down simultaneously. If both push at the same time, they effectively break the see-saw (analogous to shoot-through). By introducing a small delay between their pushes (dead time), we ensure one person goes down before the other, maintaining the see-saw functionality without damage.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Low-Side Switch: A simpler switch configuration that connects loads to ground.
-
High-Side Switch: A more complex switch that needs higher gate voltage than the supply.
-
Half-Bridge: A configuration with two MOSFETs controlling a common load and must manage shoot-through.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
Low-side switches are often used in LED drivers where the risks associated with ground floating are minimal.
-
High-side switches are typically used in motor control circuits requiring isolation of the ground.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
π΅ Rhymes Time
-
Low-side connects, easy to see, high-side needs pumps to set it free.
π Fascinating Stories
-
Imagine two friends at a light switch party, one at the top and one at the bottom. Both can't turn on at the same time, or the whole room goes dark, hence they take turns, known as dead time.
π§ Other Memory Gems
-
LHS - Low connects, HHS - High hot, BHS - Both must wait.
π― Super Acronyms
LHS, HHS, and BHS for Low-side, High-side, and Both-side management.
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: LowSide Switch
Definition:
A switching configuration where the MOSFET connects the load to ground.
-
Term: HighSide Switch
Definition:
A configuration where the MOSFET connects the load to the power supply, requiring a gate voltage greater than the supply.
-
Term: HalfBridge
Definition:
A MOSFET configuration using two transistors to control a load between them, allowing both control and direction of current flow.
-
Term: Charge Pump
Definition:
A circuit that uses capacitors to increase voltage to a level higher than the input supply.
-
Term: ShootThrough
Definition:
An undesirable condition in a half-bridge where both MOSFETs are on simultaneously, causing a short circuit.
-
Term: Dead Time
Definition:
The intentional delay inserted between the switching off of one MOSFET and the switching on of another in a half-bridge to prevent shoot-through.