RH56D-PCI Ver la hoja de datos (PDF) - Unspecified

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RH56D-PCI

Host-Controlled V.90/K56flex™ Modem device Family for Desktop Applications

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RH56D-PCI Modem Designer’s Guide

on one side only, then the isolation trace can be kept contiguous by briefly passing it to the other side of the PCB to jump

over the signal traces.

10. Avoid right angle (90 degree) turns on high frequency traces. Use smoothed radiuses or 45 degree corners.

11. Minimize the number of through-hole connections (feedthroughs/vias) on traces carrying high frequency signals.

12. Keep all signal traces away from crystal circuits.

13. Distribute high frequency signals continuously on a single trace rather than several traces radiating from one point.

14. Provide adequate clearance (e.g., 60 mil minimum) around feedthroughs in any internal planes in the DAA circuit.

15. Eliminate ground loops, which are unexpected current return paths to the power source.

16. Route PCICLK in accordance with Section 4.2.3.

4.1.4 Power

1. Identify digital power (VDD) and analog power (AVDD) supply connections.

2. Place a 10 µF electrolytic or tantalum capacitor in parallel with a ceramic 0.1 µF capacitor between power and ground at

one or more points in the digital section. Place one set nearest to where power enters the PCB (edge connector or power

connector) and place another set at the furthest distance from where power enters the PCB. These capacitors help to

supply current surge demands by the digital circuits and prevent those surges from generating noise on the power lines

that may affect other circuits.

3. For 2-layer boards, route a 200-mil wide power trace on two edges of the same side of the PCB around the border of the

circuits using the power. (Note that a digital ground trace should likewise be routed on the other side of the board.)

4. Generally, route all power traces before signal traces.

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