AR# 42783


MIG DDR2/DDR3 - Termination for Data Mask (DM) Signal when DM is disabled


The Memory Controller drives the Data Mask (DM) signal when it is enabled during MIG generation through the CORE Generator tool.

However, if the DM signal is disabled, all DM signals should be pulled to ground at the memory with a resistor value set defined by the memory vendor. 

Make sure that you verify all terminations through IBIS or other signal integrity simulations.

NOTE: This answer record is a part of the Xilinx MIG Solution Center (Xilinx Answer 34243)

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It is necessary to pull down the Data Mask signal at the memory.

The FPGA is no longer driving the DM when DM is disabled, and therefore it must be properly pulled down to prevent accidental masking of data during writes to the memory. 

If the DM is not terminated properly, it can cause calibration failures and data errors during normal operation. 

Refer to the memory vendor datasheet for appropriate termination. 

Inappropriate termination can cause problems.

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
34556 MIG Virtex-6 DDR2/DDR3 - Termination and I/O Standard Guidelines N/A N/A
AR# 42783
Date 08/28/2014
Status Active
Type Solution Center
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