• State TI Thinks Resolved
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 47 subscribers
  • Views 59 views
  • Users 0 members are here
Support feedback
Options
Options
Related

ADS122S14: Daisy Chain

ttd
Mastermind 9335 points

Part Number: ADS122S14
Other Parts Discussed in Thread: ADS124S08, ADS124S18,

Dear Technical Support Team,

How many ADS122S14s can they connects together with Dasiy chain?

According to  datasheet, equation 13 shows the calcuration.

For example, If fDATA=4ksps such as ADS124S08, the result is 78 ADCs with daisy chain.

We're aiming for up to 64 channels, but would it be better to split the daisy chain into configurations of 16 or 8 channels?

image.png

Best Regards,

ttd

  • 0
    TI__Prodigy 220 points

    Hello ttd,

    The equation uses timing as a constraint to determine the maximum number of devices in a chain. 64 devices is feasible, but SCLK integrity may degrade depending on trace length and routing.

    When you say 64 channels, do you mean 64 ADCs in a chain, or 64 analog input channels (8 ADCs)? If 64 ADCs, what application are you targeting?

    Also worth noting: the ADS124S18 will be released in August. It is another delta-sigma ADC with 18 analog inputs and daisy-chain support, compared to the 8 analog input channels on the ADS122S14. 

    Regards,
    Mason

  • 0 in reply to Mason Marrero
    Mastermind 9335 points

    Hi Mason,

    Thank you for your response.
    Since daisy-chaining 64 ADS122S14 devices would make the SPI wiring quite complicated, I thought using 8 or 4 devices would be more practical.

    Also, the application is for temperature measurement. I plan to connect one RTD or thermocouple to each ADC.

    So 64 ADS122S14s are requred for application. 

    Thank you also for the information on the new ADS124S18. I’ll check the datasheet once it’s released in August. With 18 channels, would it be possible, for example, to connect two sets of 3-wire RTDs?

    Best Regards,

    ttd

  • 0 in reply to ttd
    TI__Prodigy 220 points

    Hi ttd,

    Thank you for the clarification. Splitting into smaller groups of ADCs will make the routing less complex. 

    It will be possible to connect two sets of three wire RTDs to the new ADS124S18. 

    Regards,
    Mason