This section of the MIG Design Assistant focuses on the ZQ Calibration defined by the JEDEC Specification, as it applies to the MIGSpartan-6 MCBDDR3 designs.
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The ZQ Calibration command is used to calibrate DDR3 DRAM Ron & ODT values over PVT. The DDR3 SDRAM needs a longer time to calibrate Ron & ODT at initialization (ZQ long calibration or ZQCL) and relatively smaller time to perform periodic calibrations (ZQ short calibration or ZQCS).
The ZQCL command is used to perform the initial calibration during the power-up initialization sequence. The Spartan-6 MCB supports the ZQCL calibration during the initialization phase only.
The ZQCS command is used to perform periodic calibrations to account for VT variations.The Spartan-6 MCB does not support ZQCS calibration.