AS115 austriamicrosystems, AS115 Datasheet - Page 11

• Manufacturer Part Number: AS115
• Description: Quad Lvds Receivers
• Manufacturer: austriamicrosystems

AS1150/AS1151
Data Sheet - A p p l i c a t i o n s
Cables and Connectors
Termination
Due to the high data rates of LVDS drivers, matched termination will prevent the generation of any signal reflections,
and reduce EMI.
Board Layout
The device should be placed as close to the interface connector as possible to minimize LVDS trace length.
Figure 18. Propagation Delay and Transition Time Test Circuit
www.austriamicrosystems.com
Supported transmission media include printed circuit board traces, backplanes, and cables.
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Use cables and connectors with matched differential impedance (typically 100Ω) to minimize impedance mis-
matches.
Balanced cables such as twisted pair offer superior signal quality and tend to generate less EMI due to magnetic
field canceling effects. Balanced cables pick up noise as common mode, which is rejected by the LVDS receiver.
Avoid the use of unbalanced cables such as ribbon cable or simple coaxial cable.
The AS1151 has integrated termination resistors connected across the inputs of each receiver. The value of the
integrated resistor is specified in
The AS1150 requires an external termination resistor. The termination resistor should match the differential imped-
ance of the transmission line and be placed as close to the receiver inputs as possible. Termination resistance val-
ues may range between 90 to 132Ω depending on the characteristic impedance of the transmission medium. Use
1% surface-mount resistors.
Keep the LVDS and any other digital signals separated from each other to reduce crosstalk.
Use a four-layer PC board that provides separate power, ground, LVDS signals, and input signals.
Isolate the input LVDS signals from each other and the output LVCMOS/LVTTL signals from each other to prevent
coupling.
Separate the input LVDS signals from the output signals planes with the power and ground planes for best results.
Table 3 on page
Generator**
* 50Ω required for pulse generator.
** When testing the AS1151, adjust the pulse generator output
to account for internal termination resistor.
Pulse
50Ω
Revision 1.19
4.
INx+
50Ω
INx-
1/4 AS1150, AS1151
Receiver Enabled
C
L
OUT
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