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AM3356: Unused DDR interface pins

Part Number: AM3356


If you do not use DDR interface, please let us know the DDR pin treatment.   No-connect? pull-up/down????

Thanks and best regards,

  • Hi,

    When not using all or part of a DDR3 interface, the proper method of handling the unused pins is to tie off the DDR_DQS[x] pins to the VDDS_DDR supply via a 1-kΩ resistor and pulling the DDR_DQSn[x] pins to ground via a 1k-Ω resistor. This must be done for each byte not used. Although these signals have internal pullup and pulldown, external pullup and pulldown provide additional protection against external electrical noise causing activity on the signals. Also, include the 49.9-Ω pulldown for DDR_VTP. The VDDS_DDR and DDR_VREF power supply terminals need to be connected to their respective power supplies even if the DDR3 interface is not being used. All other DDR3 interface pins can be left unconnected.