Calibration is performed at device configuration,
but during normal operation the voltage and temperature may change. Voltage and
temperature (VT) drift can have an effect on the alignment of the DQS with the DQ bits.
VT tracking is a feature where the internal clocks that have been matched with the
memory clock strobes (DQS) are monitored and adjusted to track any variations from the
original calibrated values.
Table 1. VT Tracking Registers
| Register Name |
Quantity |
Description |
| VTTRACK_RLDLYQTR |
Nibble |
The number of fine taps in a quarter clock
period |
| VTTRACK_RLDLYQTR_MAX |
Nibble |
The largest number of fine taps in a quarter
clock period since the tracking has started |
| VTTRACK_RLDLYQTR_MIN |
Nibble |
The smallest number of fine taps in a quarter
clock period since the tracking has started |