DM9000的布局指南

　　1. Placement， Signal and Trace Routing • Place the 10/100M magnetic as close as possible to the DM9000 （no more than 20mm） and to the RJ-45 connector. • Place the termination resistors 50Ω as close as possible to the 10/100M magnetic and the DM9000 RX± pins and TX±pins. The 50Ω resistors and grounding capacitors of TX± and RX± should be placed near the DM9000 （no more than 10mm）。 • The 25MHz crystal should not be placed near important signal traces， such as RX±receive pair and TX± transmit pair， band gap resistor， magnetic， and board edge. • Traces routed from the DM9000 RX± pair to the 10/100M magnetic and the RJ45 connector should run symmetrically， directly， identically， and closely （no more than 2mm）。 The same rule is applied to traces routed from the DM9000 TX± pair.