EP3C16F256I7N Altera, EP3C16F256I7N Datasheet - Page 109

• Manufacturer Part Number: EP3C16F256I7N
• Description: Cyclone III
• Manufacturer: Altera

Chapter 6: I/O Features in the Cyclone III Device Family
OCT Support
© December 2009
Altera Corporation
Figure 6–3
Figure 6–3. Cyclone III Device Family OCT Block Placement
Each calibration block comes with a pair of RUP and RDN pins. When used for
calibration, the RUP pin is connected to V
50-Ω ±1% resistor for an on-chip series termination value of 25 Ω or 50 Ω,
respectively. The RDN pin is connected to GND through an external 25-Ω ±1% or 50-Ω
The external resistors are compared with the internal resistance using comparators.
The resultant outputs of the comparators are used by the OCT calibration block to
dynamically adjust buffer impedance.
During calibration, the resistance of the RUP and RDN pins varies. For an estimate of
the maximum possible current through the external calibration resistors, assume a
minimum resistance of 0 Ω on the RUP and RDN pins during calibration.
±1% resistor for an on-chip series termination value of 25 Ω or 50 Ω, respectively.
shows the top-level view of the OCT calibration blocks placement.
I/O Bank 3
I/O Bank 8
Cyclone III Device Family
I/O Bank 4
I/O Bank 7
CCIO
through an external 25-Ω ±1% or
Cyclone III Device Handbook, Volume 1
I/O bank with
calibration block
I/O bank without
calibration block
Calibration block
coverage
6–9