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Altera_Forum
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10 years ago

DDR3 Memory errors but passes Calibration

Hi We are getting intermittent memory read errors from our DDR3 SDRAM Controller with UniPHY hmc in a Cyclone V Using the EMIF toolkit we can run calibration on the memory and it passes every time...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
10 years ago

I have a solution for my problem:)

My problem was power supply ripple (noise) I had over 100mV of ripple on the 1V5 power supply to the DDR3 memory. The output of the voltage regulator I had used was unstable and required extra capacitance on the output to stabilize it.

I had been running tests with the EMIF toolkit to see variation in the margins reported by the toolkit after calibration. With the ripple the reported margins were varying by over 10% each time I ran the callibration

Once I had removed the ripple the reported margins varied by less than 0.1%.

I suggest that anyone who suspects problems with calibration does the following

1 Use the EMIF toolkit to run calibrations and monitor the margins.

2 Check the hf and lf noise on the power supply voltages for the system.

Thanks