EMI Suppression Filters for Digital Equipment

Product catalog summary

Introduction
The document explores the complexities of Electromagnetic Interference (EMI) in digital circuits, focusing on noise emission, conduction, and radiation. It highlights the necessity of effective noise suppression techniques and is divided into two parts: the first part explains EMI noise emission and conduction, while the second part provides guidelines for using EMI suppression filters with practical examples.

Noise Sources in Digital Equipment
Digital signals and their harmonic components are identified as primary EMI noise sources. The document explains how harmonics, particularly higher-order ones, interfere with radio and TV signals and discusses noise in IC power supply lines due to sporadic current changes.

Suppressing EMI Noise Emission
Various approaches to suppressing EMI noise are outlined, including the use of EMI suppression filters. The document details the effectiveness of different filter types and provides guidance on improving ground patterns and component layouts to minimize noise.

How to Select and Use EMI Suppression Filters
Criteria for selecting appropriate EMI suppression filters are provided, based on circuit impedance and noise suppression performance. Examples of filter applications in different noise sources, such as clock lines and power supply cables, are included.

Differences in Noise Suppressing Effect Caused by Transmission Line Length
The document analyzes how transmission line length affects noise suppression effectiveness, presenting experimental data and suggesting methods to improve noise suppression, such as adjusting the mounting position of ferrite beads inductors and adding capacitors.

Conclusion
The manual serves as a comprehensive guide for engineers and technicians dealing with EMI noise in digital equipment, emphasizing the importance of understanding noise sources and implementing effective suppression techniques to ensure optimal performance and regulatory compliance.

Radiated Noise from Patterns and Cables
The document discusses radiated noise from signal patterns and cables, demonstrating how they can act as noise antennas. It emphasizes the use of EMI suppression filters and ground planes to mitigate noise and ensure compliance with standards like CISPRpub.22.

Common Mode Noise and Ground Pattern Improvements
Common mode noise is primarily caused by the inductance of the ground pattern. The document suggests reducing GND impedance or using EMI suppression filters to mitigate this noise. It also highlights the importance of proper GND pattern design to manage and reduce EMI noise.

Specifications and Procedures for EMI Suppression
Guidelines are provided for effective EMI suppression through component layout, shielding, and the use of EMI suppression filters. The document emphasizes the importance of component and pattern layout on Printed Wiring Boards (PWB) to minimize noise levels.

Shielding Techniques
Effective shielding involves reflection and absorption, with conductive materials like iron or aluminum recommended for shielding cases. Design considerations include minimizing openings and ensuring low impedance connections.

Selection and Use of EMI Suppression Filters
The document provides detailed information on selecting and using EMI suppression filters, focusing on their noise suppression performance and impact on signal waveform distortion. It includes specifications, procedures, and recommendations for using different types of EMI filters in various circuit conditions.

Experimental Analysis and Recommendations
Experiments analyze the noise suppressing effects of ferrite beads inductors on transmission lines of varying lengths. Recommendations include optimizing the placement of ferrite beads inductors and using a combination of inductors and capacitors for effective noise suppression.

Conclusion
The document concludes with a note on the importance of reading ratings and cautions related to storage, operation, soldering, mounting, and handling to prevent issues like smoking or burning. It emphasizes the need for approval of product specifications before ordering.

Catalog excerpts

EMI Suppression Filters for Digital Equipment-1

!Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. C33E.pdf 04.5.12 Noise Suppression by EMIFILr Digital Equipment Application Manual Murata Manufacturing Co., Ltd. Cat.No.C33E

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EMI Suppression Filters for Digital Equipment-2

!Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. Introduction Because the process of EMI noise emission, conduction and radiation from electronic circuits is complicated, it is very difficult for us to suppress such EMI noise. To improve noise suppression efficiency, we must thoroughly examine...

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EMI Suppression Filters for Digital Equipment-4

!Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. C33E.pdf 04.5.12 1 Noise Sources in Digital Equipment 1 The electronic circuits that may raise EMI noise problems use many ICs, which makes the process of EMI noise emission very complicated. To explain the EMI noise phenomena simply, this chapter...

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EMI Suppression Filters for Digital Equipment-5

C33E.pdf 04.5.12 !Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. Noise Sources in Digital Equipment 1 1. Digital Signals and Harmonic Components !Digital Signals Higher Harmonics Analysis Model 1 T : Cycle Time t =d : Duty Radio T 1 t T ƒ(x)=d(1+2A1coswot+2A2cos2wot+...) sink π d wo=2π/T,Ak=...

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EMI Suppression Filters for Digital Equipment-6

C33E.pdf 04.5.12 !Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. 1 Noise Sources in Digital Equipment Example of Digital's Spectrum Measurement !Test Circuit VCC (+5V) CERALOCK® 16MHz Measurement Point High GND IC1 : HCU04 < Signal Waveform > IC2 : HC04 IC3 : HC00 < Signal Spectrum > 120 Found...

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EMI Suppression Filters for Digital Equipment-7

C33E.pdf 04.5.12 !Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. Noise Sources in Digital Equipment Power supply noise is considered as another cause of EMI noise emission from electronic circuits. Digital IC's use DC power supplies, and the DC current on the digital IC's power supply terminal...

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EMI Suppression Filters for Digital Equipment-8

C33E.pdf 04.5.12 !Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. 1 Noise Sources in Digital Equipment 2. Radiated Noise from Digital Circuit Boards !Test Circuit VCC (+5V) CERALOCK® 16MHz GND IC2 : HC04 IC1 : HCU04 CERALOCK® 10 !Board Layout Entirely grounded IC1 (HCU04) 17.5 (in cm) !Radiated...

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EMI Suppression Filters for Digital Equipment-9

C33E.pdf 04.5.12 !Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. Noise Sources in Digital Equipment !Test Circuit VCC (+5V) CERALOCK® 16MHz 1 High GND IC2 : HC04 IC1 : HCU04 IC3 : HC00 !Board Layout 3.8 Signal Pattern 10 0.3 IC1 (HCU04) 1.7 CERALOCK® IC3 (HC00) 4.2 10 IC2 (HC04) Now we will...

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EMI Suppression Filters for Digital Equipment-10

C33E.pdf 04.5.12 !Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. 1 Noise Sources in Digital Equipment Effect of EMI Suppression Filter !Test Circuit VCC (+5V) CERALOCK® 16MHz NFW31SP506X1E (cut-off frequency 50MHz) High 30Ω GND IC2 : HC04 IC1 : HCU04 IC3 : HC00 !Board Layout 3.8 Signal Pattern...

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EMI Suppression Filters for Digital Equipment-11

C33E.pdf 04.5.12 !Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. Noise Sources in Digital Equipment 1 3. Radiated Noise from Cables !Test Circuit 1 10cm Cable VCC (+5V) CERALOCK® 16MHz Open GND IC2 : HC04 IC1 : HCU04 IC3 : HC00 !Board Layout 3.8 Open 10 IC3 (HC00) 0.3 IC1 (HCU04) 1.7 CERALOCK®...

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EMI Suppression Filters for Digital Equipment-12

C33E.pdf 04.5.12 !Note Please read rating and !CAUTION (for storage, operating, rating, soldering, mounting and handling) in this PDF catalog to prevent smoking and/or burning, etc. This catalog has only typical specifications. Therefore, you are requested to approve our product specifications or to transact the approval sheet for product specificaions before ordering. 1 Noise Sources in Digital Equipment Example of Suppressing Radiated Noise from Cable (1) 10cm Cable VCC (+5V) CERALOCK® 16MHz NFW31SP506X1E (cut-off frequency 50MHz) Open 30Ω GND IC1 : HCU04 IC2 : HC04 IC3 : HC00 !Board Layout...

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