MIC2551A MICREL [Micrel Semiconductor], MIC2551A Datasheet - Page 9

• Manufacturer Part Number: MIC2551A
• Description: USB TRANSCEIVER
• Manufacturer: MICREL [Micrel Semiconductor]

Configuration Mode
Normal
Disconnect
(D+/D– sharing)
Disconnect
Disable Mode
Prohibited
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:
May 2004
MIC2551A
• 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 >2 widths 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
VBUS/VTRM
1
/
Connected
Connected
Connected
3
Ground
inch if possible. FR-4
Open
S
and the IC for both
Table 3. Power Supply Configuration
Connected
Connected
Connected
Ground
Open
VIF
9
Normal supply configuration and operation.
VP/VM are HIGH outputs, RCV is LOW.
With OE# = 0 and SUS = 1, data lines may be driven with
external devices up to 3.6V.
With D+, D– floating, I
VP/VM are HIGH outputs, RCV is LOW.
With D+, D– floating, I
Logic controlled inputs pins are Hi-Z.
Prohibited condition.
IF
IF
draws less than 1 A.
draws less than 1 A.
Notes
M9999-051004
Micrel