EP4CE40 datasheet(139/488 Pages) ALTERA

139 / 488 page

Chapter 6: I/O Features in Cyclone IV Devices

6–33

High-Speed I/O Standards Support

May 2013

Altera Corporation

Cyclone IV Device Handbook,

Volume 1

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.

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.

Note to Figure 6–16:

(1) RS and RP values are pending characterization.

Equation 6–1. Resistor Network

Figure 6–16. RSDS, Mini-LVDS, or PPDS Interface with External Resistor Network on the Top and

Bottom I/O Banks

(1)

-------

--------------------

Figure 6–17. RSDS Interface with Single Resistor Network on the Top and Bottom I/O Banks (1)

Note to Figure 6–17:

(1) RP value is pending characterization.

RSDS Receiver

100

Cyclone IV Device

Single Resistor Network

Emulated

RSDS Transmitter

EP4CE40 Datasheet(PDF) 139 Page - Altera Corporation