Texas Instruments DS90UB925QSEVB, User Manual, Page: 18 / 36

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18 DS90UB925QSEVB User’s Guide Sept 2012
4. Appendix – Use of optional Rosenberger HSD connector (J1)
Unpopulate R68 and R71 0201 sized 0
Ω
resistor. R68 and R71 pads are on the back side
of the EVM. This will cut the stub traces to J12 and J13 (SMAs). Populate J1 (Rosenberger
HSD connector).
R71
0 ohm
0201
RIN-_SMA
VSS
RIN+ R68
0 ohm
0201
RIN-
J12
SMA
1
2
3
4
5
VSS
RIN-
J13
SMA
1
2
3
4
5
J1
HSD_2X2_open
1 2
3 4
5 6
7 8
9 10 11
12 13
RIN+
RIN+_SMA
VSS
5. Appendix – Use of optional mini-B USB connector (J2)
Use this option when connecting to standard DS90UR905Q EVB.
Populate R69 and R70 with 0201 sized 0
Ω
resistor (suggest Panasonic ERJ-1GE0R00C or
equivalent). R69 and R70 pads are on the back side of the EVM under J1. This will connect
J2. Ideally, J1 (Rosenberger HSD connector) should be removed to eliminate the stub.
Warning: R68 and R71 should not be populated when using J2.
RE
D
RIN-_USB
VIA2
CON1
1
BLK
J2
mini USB 5pin_open
1
2
3
4
5
6 78
9
VIA1
CON1
1
VSS
VSS
JP8
3-Pin Header_open
1 2 3
VSS
RIN-
JP9
3-Pin Header_open
1 2 3
RIN+
R69
0 ohm_open
0201
R70
0 ohm_open
0201
mini B:
component side
(TOP)
RIN+_USB
Add a two pin jumper on JP8 and JP9; this will ground the unused wires in the USB cable.
6. Appendix - Board Layout
Figure 5, Figure 6, Figure 7, and Figure 8 show the board layout for the DS90UB925Q EVB.
The DS90UB925Q is a 4-layer board (TOP / GND / PWR / BOTTOM). The 50
Ω
microstrip trace on the top
layer of the board is referenced to GND, and the 100
Ω
differential traces are referenced to GND.