Learn Know-how
What is EMC?
2017.12.07
Under a title “switching Noise ? EMC”, we will provide commentary on the EMC related to switching power supplies and its countermeasures. First, let us review basics of the EMC and then discuss noise countermeasures.
The first session entitled “What is the EMC?” devotes itself to the verification of terms related to the EMC which is the starting line of the discussion. There are a number of English abbreviations, including EMC, with an array of similar alphabet letters. Each term must be understood and used correctly to avoid a situation where intended meaning is not conveyed or discussions end up off the mark.
What is EMC?
EMC stands for Electromagnetic Compatibility. This term conveys the meaning “Without causing electromagnetic interference to other devices, the ability to maintain the inherent performance even subjected to electromagnetic interference from other devices”. Because of the need to sustain both of the capabilities, the term “electromagnetic compatibility” is used.
”Without causing electromagnetic interference to other devices“ means that without this proviso devices could give an electromagnetic interference to other devices. EMI stands for Electromagnetic Interference. Since generating electromagnetic waves can be linked to interference, the term EMI is often used in pair with the expression ”Emission“. In terms of switching power supplies, the action of switching generates switching noise.
Conversely, the term related to ”subject to electromagnetic interference from other devices“ is EMS (Electromagnetic Susceptibility). Used in pair with EMS is ”Immunity“. What is needed in a device is the immunity that do not cause errors, such as a malfunction, when subjected to an EMI.
Among the types of EMI are conducted emission and radiated emission. Conductive emission is propagated through wires and PCB wiring. Radiated emission is a type of noise that is emitted (radiated) through the air. With respect to these emissions, in EMS there are immunity required of the devices. The relationship between EMC, EMI and EMS is given below:
In short, in EMC, the question is whether EMI and EMS satisfy specifications and regulations. The above explanation is summarized in the table below:
| Term | Meaning | Notes |
|---|---|---|
| EMC：Electromagnetic Compatibility | Without creating electromagnetic interference, the ability to maintain the device’s inherent performance even if subjected to electromagnetic interference from another device. | Because of a need to ensure both EMI and EMS, the term “electromagnetic compatibility” is used. |
| EMI：Electromagnetic Interference | Interference with other devices by emission of electromagnetic waves. | From the standpoint of EMC, the requirement is not to produce/minimize EMI. |
| EMS：Electromagnetic Susceptibility | Immunity with respect to EMI. | From the standpoint of EMC, the requirement is a tolerance that do not produce errors even if subjected to EMI. |
| Conducted Emission | Noise that is propagated via wires and PCB wiring. | |
| Radiated Emission | Noise that is emitted (radiated) through the air. |
Next time, we will explain “The Basics of Spectrum”.
【Download Documents】 Elementary EMC for Circuit Designers Working on EMC Issues
This handbook is designed to give designers who are going to work on EMC an idea of what EMC is. It promotes a sensible understanding of the relationship between EMC and the three perspectives of semiconductor devices, product specifications, and circuits and boards.
Learn Know-how
Electrical Circuit Design
- Soldering Techniques and Solder Types
- Seven Tools for Soldering
- Seven Techniques for Printed Circuit Board Reworking
-
Basic Alternating Current (AC)
- AC Circuits: Alternating Current, Waveforms, and Formulas
- Complex Numbers in AC Circuit
- Electrical Reactance
- What is Impedance? AC Circuit Analysis and Design
- Impedance Measurement: How to Choose Methods and Improve Accuracy
- Impedance Matching: Why It Matters for Power Transfer and Signal Reflections
- Resonant Circuits: Resonant Frequency and Q Factor
- RLC Circuit: Series and Parallel, Applied circuits
- What is AC Power? Active Power, Reactive Power, Apparent Power
- Power Factor: Calculation and Efficiency Improvement
- What is PFC?
- Boundary Current Mode (BCM) PFC: Examples of Efficiency Improvement Using Diodes
- Continuous Current Mode (CCM) PFC: Examples of Efficiency Improvement Using Diode
- LED Illumination Circuits：Example of Efficiency Improvement and Noise Reduction Using MOSFETs
- PFC Circuits for Air Conditioners：Example of Efficiency Improvement Using MOSFETs and Diodes
-
Basic Direct Current (DC)
- Ohm’s Law: Voltage, Current, and Resistance
- Electric Current and Voltage in DC Circuits
- Kirchhoff’s Circuit Laws
- What Is Mesh Analysis (Mesh Current Method)?
- What Is Nodal Analysis (Nodal Voltage Analysis)?
- Thevenin’s Theorem: DC Circuit Analysis
- Norton’s Theorem: Equivalent Circuit Analysis
- What Is the Superposition Theorem?
- What Is the Δ–Y Transformation (Y–Δ Transformation)?
- Voltage Divider Circuit
- Current Divider and the Current Divider Rule
Thermal design
-
About Thermal Design
- Changes in Engineering Trends and Thermal Design
- A Mutual Understanding of Thermal Design
- Fundamentals of Thermal Resistance and Heat Dissipation: About Thermal Resistance
- Fundamentals of Thermal Resistance and Heat Dissipation: Heat Transmission and Heat Dissipation Paths
- Fundamentals of Thermal Resistance and Heat Dissipation : Thermal Resistance in Conduction
- Fundamentals of Thermal Resistance and Heat Dissipation : Thermal Resistance in Convection
- Fundamentals of Thermal Resistance and Heat Dissipation : Thermal Resistance in Emission
- Thermal Resistance Data: JEDEC Standards, Thermal Resistance Measurement Environments, and Circuit Boards
- Thermal Resistance Data: Actual Data Example
- Thermal Resistance Data: Definitions of Thermal Resistance, Thermal Characterization Parameters
- Thermal Resistance Data: θJA and ΨJT in Estimation of TJ: Part 1
- Thermal Resistance Data: θJA and ΨJT in Estimation of TJ: Part 2
- Surface Temperature Measurements: Methods for Fastening Thermocouples
- Surface Temperature Measurements: Thermocouple Mounting Position
- Surface Temperature Measurements: Treatment of Thermocouple Tips
- Surface Temperature Measurements: Influence of the Thermocouple
- Estimating TJ: Basic Calculation Equations
- Estimating TJ: Calculation Example Using θJA
- Estimating TJ: Calculation Example Using ΨJT
- Estimating TJ: Calculation Example Using Transient Thermal Resistance
- Estimation of Heat Dissipation Area in Surface Mounting and Points to be Noted
- Surface Temperature Measurements: Thermocouple Types
- Summary
- Collection of Important Points Relating to Thermal Design
Switching Noise
- Procedures in Noise Countermeasures
- What is EMC?
-
Dealing with Noise Using Capacitors
- Understanding the Frequency Characteristics of Capacitors, Relative to ESR and ESL
- Measures to Address Noise Using Capacitors
- Effective Use of Decoupling (Bypass) Capacitors Point 1
- Effective Use of Decoupling Capacitors Point 2
- Effective Use of Decoupling Capacitors, Other Matters to be Noted
- Effective Use of Decoupling Capacitors, Summary
-
Dealing with Noise Using Inductors
- Frequency-Impedance Characteristics of Inductors and Determination of Inductor’s Resonance Frequency
- Basic Characteristics of Ferrite Beads and Inductors and Noise Countermeasures Using Them
- Dealing with Noise Using Common Mode Filters
- Points to be Noted: Crosstalk and Noise from GND Lines
- Summary of Dealing with Noise Using Inductors
- Other Noise Countermeasures
- Basics of EMC – Summary
Simulation
- Thermal Simulation of PTC Heaters
- Thermal Simulation of Linear Regulators
-
Foundations of Electronic Circuit Simulation Introduction
- About SPICE
- SPICE Simulators and SPICE Models
- Types of SPICE simulation: DC Analysis, AC Analysis, Transient Analysis
- Types of SPICE simulation: Monte Carlo
- Convergence Properties and Stability of SPICE Simulations
- Types of SPICE Model
- SPICE Device Models: Diode Example–Part 1
- SPICE Device Models: Diode Example–Part 2
- SPICE Subcircuit Models: MOSFET Example―Part 1
- SPICE Subcircuit Models: MOSFET Example―Part 2
- SPICE Subcircuit Models: Models Using Mathematical Expressions
- About Thermal Models
- About Thermal Dynamic Model
- Summary
-
About the ROHM Solution Simulator
- How to Access the ROHM Solution Simulator
- Trying Out the ROHM Solution Simulator (1)
- Trying Out the ROHM Solution Simulator (2)
- Starting a Simulation Circuit in the ROHM Solution Simulator
- ROHM Solution Simulator Toolbar Functions and Basic Operations
- ROHM Solution Simulator: User Interface
- Execution of Simulations
- Method for Displaying Simulation Results
- Simulation Result Display Tool: Wavebox
- Simulation Results Display Tool: Waveform Viewer
- Customization of Simulations
- Exporting Circuit Data to PartQuest™ Explorer
- Purchasing Samples for Evaluation
- Optimization of PFC Circuits
- Optimization of Inverter Circuits
- About Thermal Simulations of DC-DC Converters
- Circuit-Theory-Based Design Simulation