EP4CE30F29C7N Datasheet, PDF (136/488 Pages) Altera Corporation – Cyclone IV Device Handbook, Volume 1

6–30
Chapter 6: I/O Features in Cyclone IV Devices
High-Speed I/O Standards Support
Designing with LVDS
Cyclone IV I/O banks support the LVDS I/O standard. The Cyclone IV GX right I/O
banks support true LVDS transmitters while the Cyclone IV E left and right I/O banks
support true LVDS transmitters. On the top and bottom I/O banks, the emulated
LVDS transmitters are supported using two single-ended output buffers with external
resistors. One of the single-ended output buffers is programmed to have opposite
polarity. The LVDS receiver requires an external 100-Ω termination resistor between
the two signals at the input buffer.
Figure 6–12 shows a point-to-point LVDS interface using Cyclone IV devices true
LVDS output and input buffers.
Figure 6–12. Cyclone IV Devices LVDS Interface with True Output Buffer on the Right I/O Banks
Transmitting Device
txout +
50 Ω
50 Ω
txout -
rxin +
100 Ω
rxin -
Cyclone IV Device
Cyclone IV
Device
Family Logic
Array
txout +
50 Ω
50 Ω
txout -
rxin +
Receiving Device
100 Ω
rxin -
Input Buffer
Output Buffer
Figure 6–13 shows a point-to-point LVDS interface with Cyclone IV devices LVDS
using two single-ended output buffers and external resistors.
Figure 6–13. LVDS Interface with External Resistor Network on the Top and Bottom I/O Banks ⁽¹⁾
Cyclone IV Device
Emulated
LVDS Transmitter
Resistor Network
RS
RP
RS
LVDS Receiver
50 Ω
50 Ω
100 Ω
Note to Figure 6–13:
(1) R_S = 120 Ω. R_P = 170 Ω.
BLVDS I/O Standard Support in Cyclone IV Devices
The BLVDS I/O standard is a high-speed differential data transmission technology
that extends the benefits of standard point-to-point LVDS to multipoint configuration
that supports bidirectional half-duplex communication. BLVDS differs from standard
LVDS by providing a higher drive to achieve similar signal swings at the receiver
while loaded with two terminations at both ends of the bus.
Cyclone IV Device Handbook,
Volume 1
May 2013 Altera Corporation