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AM3352 DDR3 VTT termination

Nikhil Tiwari
Intellectual 575 points
Other Parts Discussed in Thread: AM3352

Hi,

We are planning to interface Micron’s MT41K256M16HA-125 IT:E DDR3 with Texas Instruments AM3352 processor. There will be only one DDR3 device on our board so we are not planning to provide VTT (flyby) termination as it will be a point to point topology. All the address and control signals will be routed as per the DDR3 routing guidelines given in AM3352 datasheet. The frequency of operation will be 400MHz DDR3 Clock. Also the ambient operating temperature for the board is -40­­­C to 85C.

  1. Can you please confirm if DDR3 design without VTT will provide acceptable signal integrity if the DDR device is kept near to processor and routing guidelines followed as mentioned in datasheet?
  2. Do you foresee any signal integrity issues at the extreme temperatures without VTT termination on board?

Thanks & regards,

Nikhil

  • 0
    TI__Guru 62855 points

    Temperature change will have minimum effect on signal integrity since the AM335x DDR IO buffers are temperature compensated.  The PCB design can have significant effects on signal integrity, so you should follow the guidelines in the data sheet.

    The AM335x device will operate with DDR3 under these conditions if the PCB is designed such that it does not cause signal integrity issues.

    I also recommend you to perform a thermal analysis of your product to insure the silicon devices stay within their recommended operating range when exposed to a 85C ambient. Review the following thermal considerations.

    http://processors.wiki.ti.com/index.php/AM335x_Thermal_Considerations

    Regards,
    Paul