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Original question:

ADS52J90 Logic level of SYSREF and SYNC~

ADS52J90: Input specification for SYNCP/M and SYSREFP/M

Michel Wouters
Prodigy 210 points
Part Number: ADS52J90

Hello team,

In the ADS52J90 no specifications are given for the SYNCP/M and SYSREFP/M inputs. Can you give us the specs the signals have to conform to.

Best regards,

Michel Wouters

  • 0
    Prodigy 210 points

    Hello Team,

    Any update on this question? In the datasheet only a recommended circuit is given but we would like to know the requirements for those signals at the ADC side. So we can verify our design to that.

    Best regards,

    Michel Wouters

  • 0 in reply to Michel Wouters
    TI__Mastermind 49176 points

    Hello Michel,

    Due to US Thanksgiving holidays, our responses are delayed.

    We will provide a response to your queries next week in the order in which it was received.

    Thanks for your patience and understanding.

  • 0 in reply to Praveen Aroul
    TI__Expert 6040 points

    Michel, 

    the SYSREF and SYNC pins are standard LVDS inputs.  If you use TI's LMK048xxx family, it is very straightfoward. 

    of course, you need to follow the datasheet description of the AC coupling and VCM voltage shift considerations. you can refer to this TINA model to see if it helps. Thanks!SYNC_SYSREF_BIAS.TSC

  • 0 in reply to Xiaochen (Sean)Xu
    Prodigy 210 points

    Hello,

    In my opinion it is not standard LVDS as Vcm=0.7V for the ADS52J90 instead of 1.2V for standard LVDS. Furthermore no value is given for the differential amplitude the ADS52J90 needs at the SYSREF and SYNC inputs. So we are not able to check if our system delivers the correct signal at these inputs. Please specify the values the signals have to comply with..

    Regards,

    Michel WOuters

  • 0 in reply to Michel Wouters
    TI__Expert 6040 points

    Michel, 

    this is AC coupled LVDS signal to our ADC.  So the DC compnent of the LVDS driver doesn't matter.  LVDS standard is 350mV swing, so TI's LMK clock driver can do it well as our EVM demostrated. Other companies' chips with standard LVDS outputs will work too. 

    if you can provide your clock driver chip part number, we can evaluate better. 

    another way, you can use LVCMOS type signal as well. 

    Thanks!