Universal LVDS ribbon cable

1
Universal LVDS ribbon cable

• Marc Defossez
• 12th December 2005

2
Generic Schematic Symbol
CLK / Sync / IO
CLK / Sync / IO
IO
IO
IO
IO
IO
IO
IO
IO
IO
IO
IO
IO
PCB mounted QSE part
QSE / QTE 028-01-L-D-DP-A
IO
IO
IO
IO
IO
IO
IO
IO
IO
IO
IO
IO
CLK / Sync / IO
CLK / Sync / IO
3
Schematic Symbol

• This represents a ground connection.
• These pins are physically not available on a
  differential pair QSE / QTE Samtec connector.
• They are available when using the standard type
  QSE or QTE connectors.
• Represented with the ground connections is the
  middle-connector ground plane.

4
XLVDS Schematic Symbol
Tranmitter PCB side. Due to the symmetry of the
cable, both connectors can not be placed the same
way. The receiver side of the connector can be
found on next page.
N
N
CLK
Sync
P
P
15
14
N
N
P
P
13
12
N
N
P
P
11
10
N
N
P
P
9
8
N
N
P
P
7
6
N
N
P
P
5
4
N
N
P
P
3
2
N
N
P
P
1
0
N
N
P
P
nc
nc
PCB mounted QSE part
nc
nc
nc
nc
nc
nc
nc
nc
5
XLVDS Schematic Symbol
Receiver PCB side. Due to the symmetry of the
cable, both connectors can not be placed the same
way. The transmitter side of the connector can be
found on previous page.
N
N
CLK
Sync
P
P
15
14
N
N
P
P
13
12
N
N
P
P
11
10
N
N
P
P
9
8
N
N
P
P
7
6
N
N
P
P
5
4
N
N
P
P
3
N
2
N
P
P
1
0
N
N
P
P
PCB mounted QSE part
nc
nc
nc
nc
nc
nc
nc
nc
nc
nc
6
XVamPire Schematic Symbol
N
N
CLK
Sync
Tranmitter PCB side. On the XVamPire Board there
are 64 LVDS channels. This connector shows only
part of them. The differential IO are spread
over two banks (2TX and 2RX). When taking two
fully occupied connectors, a third one can be
used to share the remaining signals or two not
completely occupied connectors can be used only
populated with the remaining pins of the bank.
P
P
25
24
N
N
P
P
23
22
N
N
P
P
21
20
N
N
P
P
19
18
N
N
P
P
17
16
N
N
P
P
15
14
N
N
P
P
QSE / QTE 028-01-L-D-DP-A-
13
12
N
N
P
P
Clk, sync 6338
11
10
N
N
P
P
8
9
N
N
P
P
3726
6
7
N
N
P
P
4
5
N
N
P
P
2
N
3
N
250 Clk, sync
P
P
0
1
N
N
P
P
7
XVamPire Schematic Symbol
N
N
CLK
Sync
Receiver PCB side. On the XVamPire Board there
are 64 LVDS channels. This connector shows only
part of them. The differential IO are spread
over two banks (2TX and 2RX). When taking two
fully occupied connectors, a third one can be
used to share the remaining signals or two not
completely occupied connectors can be used only
populated with the remaining pins of the bank.
P
P
25
24
N
N
P
P
23
22
N
N
P
P
21
20
N
N
P
P
19
18
N
N
P
P
17
16
N
N
P
P
15
14
N
N
P
P
QSE / QTE 028-01-L-D-DP-A-
13
N
12
N
P
P
Clk, sync 6339
11
10
N
N
P
P
9
8
N
N
P
P
3726
7
6
N
N
P
P
5
4
N
N
P
P
N
3
2
N
250 Clk, sync
P
P
N
1
0
N
P
P
8
PCB Layout QSE-028-xx part
5.74
0.19
2.87
2.46
2.79
01
0.46
4.70
Number of banks x 20.00 0.13
6.35
16.13
20.00
20.00
0.41
5.02
Courtesy of SAMTEC
0.80
2.27
0.43
1.02 DIA
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PCB Layout QSE-040-xx or QSE-028-xx part
If termination resistors need to be placed
close to the connector, this can be the lay-out
otherwise these pads can be used as test points
for differential probes.
Ground connection of the middle-connector ground
shield.
If termination resistors need to be placed
close to the connector, this can be the lay-out.
A ground shield has been placed on the PCB layer
under the connector. The differential
connector does not have the ground connections
between the signal pins ! We decided to design
them in to get optimal signal shielding (creation
of a guard ring).
Ground connection of the middle-connector ground
shield.
10
Connector detailsSingle v Differential
Two different style connectors are available
from SAMTEC for the QSE/QTE series, that can
share the same PCB layout, shown
earlier. QSE-028-01-x-D-DP-A is a Differential
Pair connector and QSE-040-01-x-D-A a Single
ended connector. The differential pair connector
has a pin pair arrangement. surrounded by gaps/or
un-populated pins in the body. One out of three
pins is missing. The single ended version of the
connector can be seen as universal connector
since all pins are populated. The connector can
thus be used in single ended and differential
pair applications.
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Cable details
Cables are available from Samtec. The order
numbers - please see page on cable
specification. 50 Ohm Single ended
EQCD-040-11.81-TEU-TEU-4 100 Ohm Differential
EQDP-028-11.81-TEU-TEU-4 The connectors are
SAMTEC QSE and QTE. Specifications are available
at http//www.samtec.com http//www.samtec.com/su
ddenspecs/techspec.asp?seriesQSE Technical
specifications can be found at http//www.samtec.
com/suddenspecs/techspec_test.asp?seriesQSE
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Cable Specification READ THIS!
Customers should be aware that cables can be
specified as wired straight through or twisted,
additionally - connector mechanical polarization
must be considered . In terms of Cable wiring
connections, because a PCB is used to mount
connectors at the cable ends there are 16
different combinations that a cable wiring can be
specified. The Samtec web site provides circuit
diagrams of Cables which can be used to confirm
the suitability of any particular cable for an
application.