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DAC38J84: Specific power consumption

Izik
Expert 1585 points

Part Number: DAC38J84
Other Parts Discussed in Thread: DAC39J84, LMK04828

Hello 

Please advise what would be the power dissipation of DAC38J84 under the following conditions:

fDAC=2GSPS, 1x interpolation (or else, I will use the value that consumes less power) ,NCO on, QMC off, inverse sinc on,  GDC off, PAP off, PLL off, SerDes off (not used) 

Thanks

  • 0
    Expert 1585 points
    Hello

    Any updates on this?

    Thanks
  • 0 in reply to Izik
    TI__Guru* 91947 points

    Izik,

    This is all we have regarding power measurements with no JESD204B input data.

    Regards,

    Jim

    POWER SUPPLY MEASEREMENTS.pptx

  • 0 in reply to jim s
    Expert 1585 points

    Hi Jim

    If I look on DAC39J84 datasheet, on section 6.5 I see that under the following conditions:

    MODE 2:

    fDAC=2.5GSPS, 2x interpolation, NCO on, QMC on, invsinc on, GDC off, PAP off, PLL on, LMF=841, SerDes rate = 12.5Gbps, 20mA FS output, IF=150MHz the typical power consumption is 1.86W. According to the slides you sent, when the DAC is working under similar conditions but without SerDes and with double interpolation the power consumption is ~2W, meaning the power consumption is higher.

    When serdes is off can I assume that I save the serdes supply current?

    Can you please explain?

    Thanks

  • 0 in reply to Izik
    TI__Guru* 91947 points

    Izik,

    The engineer that made the measurements sent me the following message along with an updated power document:

    The measurements you have were misleading (it included 3.3V rail of LMK04828). We had re-done the measurements with the LMK04828 3.3V rail excluded (see attached). These measurements show a power consumption of 670mW instead of the 2W.

     

    The 3.3V rail supplies the DAC and the LMK04828. To read the correct current consumption, the customer needs to measure these separately.

     

    Also, turning off the serdes lanes will save supply current (although it will not be significant).

     

    Regards,

    Jim

    6201.POWER SUPPLY MEASEREMENTS.pptx