EP4CE30F29C7N Datasheet, PDF (116/488 Pages) Altera Corporation – Cyclone IV Device Handbook, Volume 1

6–10
Chapter 6: I/O Features in Cyclone IV Devices
OCT Support
Figure 6–3 shows the external calibration resistors setup on the RUP and RDN pins and
the associated OCT calibration circuitry.
Figure 6–3. Cyclone IV Devices R_S OCT with Calibration Setup
Cyclone IV Device Family OCT with
Calibration with RUP and RDN pins
V_CCIO
RUP
External
Calibration
Resistor
OCT
Calibration
Circuitry
V_CCIO
RDN
External
Calibration
Resistor
GND
RUP and RDN pins go to a tri-state condition when calibration is completed or not
running. These two pins are dual-purpose I/Os and function as regular I/Os if you
do not use the calibration circuit.
On-Chip Series Termination Without Calibration
Cyclone IV devices support driver impedance matching to match the impedance of
the transmission line, which is typically 25 or 50 Ω. When used with the output
drivers, OCT sets the output driver impedance to 25 or 50 Ω. Cyclone IV devices also
support I/O driver series termination (R_S = 50 Ω) for SSTL-2 and SSTL-18.
Cyclone IV Device Handbook,
Volume 1
May 2013 Altera Corporation