Uncalibrated OCT (Output)
I/O Standard
R
S
(Ω)
25
Differential 1.5 V HSTL Class II
50
Differential 1.2 V HSTL Class I
25
Differential 1.2 V HSTL Class II
25, 50, 34, 40
SSTL-15
34, 40
SSTL-135
34, 40
SSTL-125
34, 40, 48, 60, 80
HSUL-12
25, 50, 34, 40
Differential SSTL-15
34, 40
Differential SSTL-135
34, 40
Differential SSTL-125
34, 40, 48, 60, 80
Differential HSUL-12
Driver-impedance matching provides the I/O driver with controlled output impedance that closely matches
the impedance of the transmission line. As a result, you can significantly reduce signal reflections on PCB
traces.
If you select matching impedance, current strength is no longer selectable.
Figure 5-13: R
S
OCT Without Calibration
This figure shows the R
S
as the intrinsic impedance of the output transistors.
V
CCIO
R
S
R
S
GND
Z
0
= 50 Ω
Driver
Series Termination
Receiving
Device
Related Information
On-Chip I/O Termination in Cyclone V Devices
on page 5-34
R
S
OCT with Calibration in Cyclone V Devices
The Cyclone V devices support R
S
OCT with calibration in all banks.
I/O Features in Cyclone V Devices
Altera Corporation
CV-52005
R
S
OCT with Calibration in Cyclone V Devices
5-36
2014.01.10