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ADS5263: Optimal input impedance termination

XIN LI
Prodigy 55 points
Part Number: ADS5263
Other Parts Discussed in Thread: VCA2615,

Hi, 

I would like to know if optimal termination resistors attached to the VCM exit. From EVM I see 50Ohm termination (25Ohm x 2) shunt near ADC input and with 1:1 balun (the other 2 shunt 12.5Ohm resistors at output of balun are used to match the balun I guess). In our case we have VCA2615 (differential output impedance=6Ohm) to drive the ADC input. The VCA2615 recommands high differential load impedance like 500Ohm even mode impedance for each rail. Is that OK for ADC to be with high termination resistors ?

Thanks

XL

  • 0
    TI__Genius 12025 points

    Hi,

    How are you!

    Thank you for using TI VCA2615 and ADS5263 devices.

    Since you are using VCA2615 to drive ADS5263 (as close as possible),

    then only VCA2615 needs to take care of the input signal termination.

    Also because ADC input pins are also driven by its VCM DC signal,

    therefore the input impedance termination will be taken care by VCA2615.

    Thank you!

    Best regards,

    Chen