EP4CE30F29C7N Datasheet, PDF (139/488 Pages) Altera Corporation – Cyclone IV Device Handbook, Volume 1

Chapter 6: I/O Features in Cyclone IV Devices
High-Speed I/O Standards Support
6–33
Figure 6–16. RSDS, Mini-LVDS, or PPDS Interface with External Resistor Network on the Top and
Bottom I/O Banks ⁽¹⁾
Note to Figure 6–16:
(1) R_S and R_P values are pending characterization.
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.
Equation 6–1. Resistor Network
R_-----S----×_-----^R-----_2----^P_---
R_S
+
R_-----P-
2
=
50
Ω
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 Figure 6–17. The external
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 shows the RSDS interface with a single resistor network on the top and
bottom I/O banks.
Figure 6–17. RSDS Interface with Single Resistor Network on the Top and Bottom I/O Banks ⁽¹⁾
Cyclone IV Device
Emulated
RSDS Transmitter
Single Resistor Network
RSDS Receiver
50 Ω
R_P
100 Ω
50 Ω
Note to Figure 6–17:
(1) R_P value is pending characterization.
May 2013 Altera Corporation
Cyclone IV Device Handbook,
Volume 1