MIC2551(2003) Ver la hoja de datos (PDF) - Micrel

Número de pieza

componentes Descripción

Fabricante

MIC2551
(Rev.:2003)

USB Transceiver

Micrel 

MIC2551

PCB Layout Recommendations

Although the USB standard and applications are not based in

an impedance controlled environment, a properly designed

PCB layout is recommended for optimal transceiver perfor-

mance. The suggested PCB layout hints are as follows:

• Match signal line traces (VP/VM, D+, D–) to

40ps, approximately 1/3 inch if possible. FR-4

PCB material propagation is about 150ps/inch,

so to minimize skew try to keep VP/VM, D+/D–

traces as short as possible.

• For every signal line trace width (w), separate

the signal lines by 1.5–2 widths. Place all other

traces at >2 widths from all signal line traces.

• Maintain the same number of vias on each

differential trace, keeping traces approximately

at same separation distance along the line.

• Control signal line impedances to ±10%.

• Keep RS as close to the IC as possible, with

equal distance between RS and the IC for both

D+ and D–.

Micrel

January 2003

9

MIC2551

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