Cyclone® V Device Handbook: Volume 1: Device Interfaces and Integration

ID 683375
Date 10/18/2023
Public
Document Table of Contents

5.9.2. RS OCT with Calibration in Cyclone® V Devices

The Cyclone® V devices support RS OCT with calibration in all banks.

Table 55.  Selectable I/O Standards for RS OCT With CalibrationThis table lists the output termination settings for calibrated OCT on different I/O standards.
I/O Standard Calibrated OCT (Output)
RS (Ω) RZQ (Ω)
3.0 V LVTTL/3.0 V LVCMOS 25/50 100
2.5 V LVCMOS 25/50 100
1.8 V LVCMOS 25/50 100
1.5 V LVCMOS 25/50 100
1.2 V LVCMOS 25/50 100
SSTL-2 Class I 50 100
SSTL-2 Class II 25 100
SSTL-18 Class I 50 100
SSTL-18 Class II 25 100
SSTL-15 Class I 50 100
SSTL-15 Class II 25 100
1.8 V HSTL Class I 50 100
1.8 V HSTL Class II 25 100
1.5 V HSTL Class I 50 100
1.5 V HSTL Class II 25 100
1.2 V HSTL Class I 50 100
1.2 V HSTL Class II 25 100
Differential SSTL-2 Class I 50 100
Differential SSTL-2 Class II 25 100
Differential SSTL-18 Class I 50 100
Differential SSTL-18 Class II 25 100
Differential SSTL-15 Class I 50 100
Differential SSTL-15 Class II 25 100
Differential 1.8 V HSTL Class I 50 100
Differential 1.8 V HSTL Class II 25 100
Differential 1.5 V HSTL Class I 50 100
Differential 1.5 V HSTL Class II 25 100
Differential 1.2 V HSTL Class I 50 100
Differential 1.2 V HSTL Class II 25 100
SSTL-15 25, 50 100
34, 40 240
SSTL-135 34, 40 240
SSTL-125 34, 40 240
HSUL-12 34, 40, 48, 60, 80 240
Differential SSTL-15 25, 50 100
34, 40 240
Differential SSTL-135 34, 40 240
Differential SSTL-125 34, 40 240
Differential HSUL-12 34, 40, 48, 60, 80 240

The RS OCT calibration circuit compares the total impedance of the I/O buffer to the external reference resistor connected to the RZQ pin and dynamically enables or disables the transistors until they match.

Calibration occurs at the end of device configuration. When the calibration circuit finds the correct impedance, the circuit powers down and stops changing the characteristics of the drivers.

Figure 85. RS OCT with CalibrationThis figure shows the RS as the intrinsic impedance of the output transistors.