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Adventurer
Adventurer
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Registered: ‎08-09-2013

DDR3 VREF getting 1.5V on power on - kintex7 410T

Hi, 

We have a custom board in which we have kintex7 410T FPGA with 8 bit DDR3 from micron. The device requires 1.5V supply and 0.75V. VREF.

We use LTM4622 chip for powering the DDR3. When the board is powered up voltage on VREF is stable with 0.75V. 

Case 1

When we load design file without mig ip core in FPGA, voltage is stable at 0.

75V.

Case 2

When we load design with with mig core in FPGA , voltage on VREF is immediately shooting to 1.5V.

The memory test is failing. We able to see no data write into memory. We were not able to find any short in the board between 1.5V and 0.75V.

We do not understand this issue. Can anyone please help.

We tried various settings in MIG core

We could not solve the issue.

Regards,

Rajesh khanna

 

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Moderator
Moderator
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Registered: ‎08-21-2007

The VREF pins are unused IOs in your project in case1. Please check the settings for the unused IOs.

 

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