EP2AGX95EF29C6N Datasheet, PDF (183/380 Pages) Altera Corporation – Device Interfaces and Integration

Chapter 6: I/O Features in Arria II Devices
OCT Support
6–19
OCT Support
Arria II devices feature OCT to provide I/O impedance matching and termination
capabilities. OCT maintains signal quality, saves board space, and reduces external
component costs.
Arria II devices support the following features:
■ “R_S OCT Without Calibration for Arria II Devices”
■ “R_S OCT with Calibration for Arria II Devices”
■ “Left-Shift R_S OCT Control for Arria II GZ Devices”
■ “Expanded R_S OCT with Calibration for Arria II GZ Devices”
■ “R_D OCT for Arria II LVDS Input I/O Standard”
■ “R_T OCT with Calibration for Arria II GZ Devices”
■ “Dynamic R_S and R_T OCT for Single-Ended I/O Standard for Arria II GZ Devices”
Arria II devices support OCT in all user I/O banks by selecting one of the OCT I/O
standards. Arria II devices support OCT in the same I/O bank with different I/O
standards if they use the same VCCIO supply voltage. You can independently
configure each I/O buffer in an I/O bank to support OCT or programmable current
strength. However, you cannot configure both R_S OCT and programmable current
strength for the same I/O buffer.
A pair of RUP and RDN pins are available in a given I/O bank for Arria II GX
series-calibrated termination and shared for Arria II GZ series- and parallel-calibrated
termination. RUP and RDN pins share the same V_CCIO and GND, respectively, with the
I/O bank where they are located. RUP and RDN pins are dual-purpose I/Os, and
function as regular I/Os if you do not use the calibration circuit.
For R_S OCT, the connections are as follows:
■ The RUP pin is connected to V_CCIO through an external 25-±1% or 50-±1%
resistor for an on-chip series termination value of 25- or 50-, respectively.
■ The RDN pin is connected to GND through an external 25-±1% or 50-±1%
resistor for an R_S OCT value of 25-or 50-, respectively.
For R_T OCT, the connections are as follows:
■ The RUP pin is connected to V_CCIO through an external 50- ±1% resistor.
■ The RDN pin is connected to GND through an external 50- ±1% resistor.
R_S OCT Without Calibration for Arria II Devices
Arria II devices support driver-impedance matching to provide the I/O driver with
controlled output impedance that closely matches the impedance of the transmission
line. As a result, you can significantly reduce reflections. Arria II devices support
R_S OCT for single-ended I/O standards.
December 2011 Altera Corporation
Arria II Device Handbook Volume 1: Device Interfaces and Integration