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5.9.3. RT OCT with Calibration in Cyclone® V Devices
The Cyclone® V devices support RT OCT with calibration in all banks. RT OCT with calibration is available only for configuration of input and bidirectional pins. Output pin configurations do not support RT OCT with calibration. If you use RT OCT, the VCCIO of the bank must match the I/O standard of the pin where you enable the RT OCT.
I/O Standard | Calibrated OCT (Input) | |
---|---|---|
RT (Ω) | RZQ (Ω) | |
SSTL-2 Class I | 50 | 100 |
SSTL-2 Class II | 50 | 100 |
SSTL-18 Class I | 50 | 100 |
SSTL-18 Class II | 50 | 100 |
SSTL-15 Class I | 50 | 100 |
SSTL-15 Class II | 50 | 100 |
1.8 V HSTL Class I | 50 | 100 |
1.8 V HSTL Class II | 50 | 100 |
1.5 V HSTL Class I | 50 | 100 |
1.5 V HSTL Class II | 50 | 100 |
1.2 V HSTL Class I | 50 | 100 |
1.2 V HSTL Class II | 50 | 100 |
Differential SSTL-2 Class I | 50 | 100 |
Differential SSTL-2 Class II | 50 | 100 |
Differential SSTL-18 Class I | 50 | 100 |
Differential SSTL-18 Class II | 50 | 100 |
Differential SSTL-15 Class I | 50 | 100 |
Differential SSTL-15 Class II | 50 | 100 |
Differential 1.8 V HSTL Class I | 50 | 100 |
Differential 1.8 V HSTL Class II | 50 | 100 |
Differential 1.5 V HSTL Class I | 50 | 100 |
Differential 1.5 V HSTL Class II | 50 | 100 |
Differential 1.2 V HSTL Class I | 50 | 100 |
Differential 1.2 V HSTL Class II | 50 | 100 |
SSTL-15 | 20, 30, 40, 60,120 | 240 |
SSTL-135 | 20, 30, 40, 60, 120 | 240 |
SSTL-125 | 20, 30, 40, 60, 120 | 240 |
Differential SSTL-15 | 20, 30, 40, 60,120 | 240 |
Differential SSTL-135 | 20, 30, 40, 60, 120 | 240 |
Differential SSTL-125 | 20, 30, 40, 60, 120 | 240 |
The RT OCT calibration circuit compares the total impedance of the I/O buffer to the external resistor connected to the RZQ pin. The circuit dynamically enables or disables the transistors until the total impedance of the I/O buffer matches the external resistor.
Calibration occurs at the end of the device configuration. When the calibration circuit finds the correct impedance, the circuit powers down and stops changing the characteristics of the drivers.