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ADS4449: Is it possible for multi ADS4449 synchronization?

LiehChun Chang
Prodigy 100 points
Part Number: ADS4449
Other Parts Discussed in Thread: ADS42LB69,

Hi,

I am evaulating multi channels ADC. My application needs 12 channels ADC. If I choosed ADC like ADS42LB69 , the design will use 6 ADCs. But if ADS4449 , only 3 ADCs will be used.

ADS4449 doesn't have sync pin. Is it possible to use synchronied clock and power down pin to complete the synchronization between multi ADS4449?

  • +1
    TI__Guru* 91947 points

    LiehChun,

    Below is skew data data between the AB and CD output clock collected over 20 samples: 

    Skew, from CD clock rise to AB clock rise(ns), measured at 250MSPS, is given in table below.

     

    Temp, C

    Dvdd,V

    -40

    25

    85

    1.816

    0.25

    0.213

    0.077056

    1.916

    0.239

    0.202

    0.065736

    2.016

    0.2996

    0.203

    0.045172

    Other supplies (AVDD3V and AVDD) were kept at 3.3V and 1.9V respectively.

    You would have to make sure the FPGA that is capturing the data from the three devices will meet the setup and hold time for the 6 clocks involved. Depending on the sampling rate and the delay of the input clock going to the three parts, this may be achievable. This probably would require using the same clock for all parts, minimize skew on clock routing, matching skew lengths on all data outputs and if possible, using the same power supply. 

    Regards,

    Jim