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CY7C68000A
Document #: 38-08052 Rev. *G Page 13 of 15
PCB Layout Recommendations
Follow these recommendations to ensure reliable, high-perfor-
mance operation
[3]
.
■ A four-layer impedance controlled board is required to maintain
signal quality
■ Specify impedance targets (ask your board vendor what they
can achieve)
■ To control impedance, maintain trace widths and trace spacing
to within written specifications
■ Minimize stubs to minimize reflected signals
■ Connections between the USB connector shell and signal
ground must be done near the USB connector
■ Bypass and flyback capacitors on VBus, near the connector,
are recommended
■ Keep DPLUS and DMINUS trace lengths within 2 mm of each
other in length, with preferred length of 20 to 30 mm
■ Maintain a solid ground plane under the DPLUS and DMINUS
traces. Do not split the plane under these traces
■ Do not place vias on the DPLUS or DMINUS trace routing
■ Isolate the DPLUS and DMINUS traces from all other signal
traces by no less than 10 mm
Package Diagrams (continued)
Figure 7. 56 VFBGA (5 x 5 x 1.0 mm) 0.50 Pitch, 0.30 Ball BZ56
TOPVIEW
PINA1CORNER
0.50
3.50
5.00±0.10
BOTTOMVIEW
0.10(4X)
3.50
5.00±0.10
0.50
Ø0.15MCAB
Ø0.05MC
Ø0.30±0.05(56X)
A1CORNER
-B-
-A-
1.0max
0.160~0.260
0.080C
0.45
SEATINGPLANE
0.21
0.10C
-C-
SIDEVIEW
5.00±0.10
5.00±0.10
REFERENCEJEDEC:MO-195C
PACKAGEWEIGHT:0.02 grams
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D
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13265486
7856 2341
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H
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001-03901-*B
Note
3. Source for recommendations: EZ-USB FX2™ PCB Design Recommendations, http:///www.cypress.com/cfuploads/support/app_notes/FX2_PCB.pdf
High-Speed USB Platform Design Guidelines, http://www.usb.org/developers/docs/hs_usb_pdg_r1_0.pdf.
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