Multitech MT9234SMI-HV-92 Specifications download pdf (Page 16)

CHAPTER 3 – UNIVERSAL DESIGN CONSIDERATIONS

Universal Socket Developer Guide

Chapter 3 – Universal Design Considerations

Noise Suppression Design Considerations

Adhere to engineering noise-suppression practices when designing a printed circuit board (PCB) containing the

SocketModem. Noise suppression is essential to the proper operation and performance of the modem and

surrounding equipment.

Any OEM board design that contains the SocketModem should consider both on-board and off-board generated

noise that can affect digital signal processing. Both on-board and off-board generated noise that is coupled on-

board can affect interface signal levels and quality. Noise in frequency ranges that affect modem performance is of

particular concern.

On-board generated electromagnetic interference (EMI) noise that can be radiated or conducted off-board is

equally important. This type of noise can affect the operation of surrounding equipment. Most local government

agencies have stringent certification requirements that must be met for use in specific environments.

Proper PC board layout (component placement, signal routing, trace thickness and geometry, etc.) component

selection (composition, value, and tolerance), interface connections, and shielding are required for the board

design to achieve desired modem performance and to attain EMI certification.

Other aspects of proper noise-suppression engineering practices are beyond the scope of this guide. Consult noise

suppression techniques described in technical publications and journals, electronics and electrical engineering text

books, and component supplier application notes.

PC Board Layout Guidelines

In a 4-layer design, provide adequate ground plane covering the entire board. In 4-layer designs, power and

ground are typically on the inner layers. All power and ground traces should be 0.05 inches wide.

The recommended hole size for the SocketModem pins is 0.036 in. +/-0.003 in. in diameter. Use spacers to hold

the SocketModem vertically in place during the wave solder process.

All creepages and clearances for the SocketModem have been designed to meet requirements of safety standards

EN60950 or EN60601. The requirements are based on a working voltage of 125V or 250V. When implementing the

recommended DAA* circuit interface in a third party design, strictly follow all creepage and clearance

requirements in order to meet safety standards. The third party safety design must be evaluated by the

appropriate national agency per the required specification.

User accessible areas

Based on where the third party design is to be marketed, sold, or used, it may be necessary to provide an

insulating cover over all TNV exposed areas. Consult with the recognized safety agency to determine the

requirements.

Note:

Even if the recommended design considerations are followed, there are no guarantees that a particular

system will comply with all the necessary regulatory requirements. It is imperative that specific designs be

completely evaluated by a qualified/recognized agency.

*DAA stands for Data Access Arrangement. DAA is the telephone line interface of the SocketModem.

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Multitech MT9234SMI-HV-92 Specifications Page 16