MIC2550A Micrel Semiconductor, MIC2550A Datasheet - Page 9

• Manufacturer Part Number: MIC2550A
• Description: Universal Serial Bus Transceiver
• Manufacturer: Micrel Semiconductor

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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:
March 2005
MIC2550A
• Match signal line traces (VP/VM, D+, D–) to
• For every signal line trace width (w), separate
• Maintain the same number of vias on each
• Control signal line impedances to ±10%.
• Keep R
40ps, approximately
PCB material propagation is about 150ps/inch,
so to minimize skew try to keep VP/VM, D+/D–
traces as short as possible.
the signal lines by 1.5–2 widths. Place all other
traces at >2w from all signal line traces.
differential trace, keeping traces approximately
at same separation distance along the line.
equal distance between R
D+ and D–.
S
as close to the IC as possible, with
1
/
3
inch if possible. FR-4
S
and the IC for both
9
M9999-031805
Micrel, Inc.