Altera Cyclone IV Device Handbook page 139

Chapter 6: I/O Features in Cyclone IV Devices
High-Speed I/O Standards Support
Figure 6–16. RSDS, Mini-LVDS, or PPDS Interface with External Resistor Network on the Top and
Bottom I/O Banks
Note to
(1) R
A resistor network is required to attenuate the output voltage swing to meet RSDS,
mini-LVDS, and PPDS specifications when using emulated transmitters. You can
modify the resistor network values to reduce power or improve the noise margin.
The resistor values chosen must satisfy
Equation 6–1. Resistor Network
1
Altera recommends that you perform simulations using Cyclone IV devices IBIS
models to validate that custom resistor values meet the RSDS, mini-LVDS, or PPDS
requirements.
It is possible to use a single external resistor instead of using three resistors in the
resistor network for an RSDS interface, as shown in
single-resistor solution reduces the external resistor count while still achieving the
required signaling level for RSDS. However, the performance of the single-resistor
solution is lower than the performance with the three-resistor network.
Figure 6–17
bottom I/O banks.
Figure 6–17. RSDS Interface with Single Resistor Network on the Top and Bottom I/O Banks
Note to
(1) R
March 2016 Altera Corporation
(1)
Figure 6–16:
and R values are pending characterization.
S P
R
------------------- -
R
shows the RSDS interface with a single resistor network on the top and
Cyclone IV Device
Emulated
RSDS Transmitter
Single Resistor Network
Figure 6–17:
value is pending characterization.
P
Equation 6–1.
R
P

------ -
S
2
50 
=
R
P
------ -
+
S
2
Figure
50 Ω
R
P
50 Ω
6–17. The external
RSDS Receiver
100 Ω
Cyclone IV Device Handbook,
Volume 1
6–33
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