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Products Tested | CE Assistance (EMC)

CE Marking is the manufacturer's declaration showing compliance with applicable European Union (EU) directives. For most end-user products sold in the EU, the use of the CE Mark and a Declaration of Conformity are mandatory. Most electronic products classified as "apparatus" (as opposed to "component") require a CE mark. Rabbit Semiconductor products are primarily components of control systems, but may sometimes be used as apparatus, depending on the application. Most Rabbit Semiconductor products have or are in the process of obtaining CE Mark certification.

Rabbit Semiconductor reviews all pertinent directives and standards to determine the tests appropriate for product compliance. Working closely with an EU-certified competent body, Rabbit Semiconductor determined that the EMC Directive was the most applicable test guideline for Rabbit Semiconductor single-board computers (SBCs).

The EMC Directive tests basic product performance requirements for emissions and immunity. The emissions criteria make certain that the product does not interfere with electronics in its typical surroundings. The immunity criteria make certain that the product does not fail due to external electronics in its typical surroundings. These surroundings are classified under industrial or commercial surroundings. The immunity test gives greater weight to industrial grade surroundings, while the emission test gives greater weight to commercial grade surroundings.

Rabbit-Based Single-Board Computers

Note: The controller is CE-compliant if it has the CE mark.

Z180-Based Single-Board Computers

Z180-Based Packaged Single-Board Computers

RCM Models – RabbitCore Microprocessor Core Modules

All RabbitCore models are considered components that are embedded into OEM equipment/devices. EMC testing for these devices/equipment must be done by the integrator or by the end-user of the equipment/device. For in-house emissions testing data on RabbitCores, please contact Customer Service.

Notes:

1. Only SBCs with operator interfacing are tested for ESD.
2. I/O cables longer than 3 meters need to be routed as separate shielded cables.
3. SBCs with relays need to limit relay voltages to less than 50V AC and 75V DC to maintain CE compliance.
4. The power supply provided with development kits are for development purposes only. It is the customers' responsibility to provide clean DC supply to the SBC for all applications in end-products. A power supply CE certified to the EMC Directive is recommended.
5. The CB Test Certification is a safety test and not part of the EMC Directive. This test determines other characteristics like non-explosive safety features, non-flammability and construction ruggedness.
6. The OP7100 has been tested to meet EN55022 Class A emissions standard with ferrite RFI suppressers on the I/O cables. Additional shielding or filtering may be needed to meet Class B emission standards.

CE Compliance Assistance (EMC)

Rabbit Semiconductor SBCs are CE tested to varied levels of emissions and immunity, and are generally CE tested to Light Industrial Immunity standards. If an SBC will be used in a heavy industrial environment, additional shielding and/or filtering may be required. The following information is provided to Rabbit Semiconductor customers who require a higher level of immunity and/or higher class of emissions.

Enclosures and Shielding

1. Wavelength approximation (air): l = 300/F (MHz)
(where l = Wavelength (in meters) and F = frequency)

2. Using a cast metal enclosure is best as it does not have a structural joint.

• Seams of fabricated enclosures should have continuous welds.
• Mask paint from screw or pin holes when fastening different panels together.
• EMI gaskets improve the conductive path between panels. (Use a gasket material with conductive properties that are comparable to the enclosure material.)
• Conductive paint can be used to provide RF shielding of plastic enclosures, and can improve shielding of metal enclosures.
• EMI shielding tapes are very effective in reducing emissions, but are not recommended as a permanent fix.

Cables

1. Transmission lines can radiate. Use shielded cables when possible, and ground cable shields at both ends to their respective equipment.
2. Use twisted pair shielded cable when appropriate.
3. Avoid parallel runs of signal and power cables.
4. Run cables away from apertures in shielding and close to conductive grounded structures.

Grounding

1. Systems should incorporate at least two separate grounds (not including safety ground). An electronics ground for the circuits and a chassis ground for hardware (racks and cabinets).
2. Connect system grounds only at the primary power ground.
3. The geometry of earth leads is very important.
• Keep ground impedance low by keeping ground straps as short as possible.
• Use a fat or thick ground conductor to minimize its RF impedance.
• A braided ground is better then a solid conductor.
4. Mask paint from conductive surfaces when attaching ground leads.

Filtering and Protection Devices

1. Use a power line filter if your equipment is susceptible to conducted emissions or surges on the AC line voltage.
2. Use a low pass filter when applicable to filter out higher frequencies.
3. Ferrite suppressors are very effective in damping out emissions on cables.

The type of transient protection device required is dependent upon the application. Table 1 lists some common EMI transient parameters. Table 2 lists specifications of various transient-suppression components.

Table 1

Table 2

The above information is provided to help select EMI problems. Electromagnetic interference can be very complex and will vary significantly between applications.

References:
EMI Gone Technical
Joe DiBartolomeo, Circuit Cellar,
Issue 91 Feb. 1998 & Issue 93 April 1998.
EMC for Product Designers
Tim Williams, Butterworth Heinemann, 1992.
Electrical Interference Handbook
Norman Elise, Reed Educational and Professional Publishing Ltd,
Second Edition 1998.