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ADS8598H: Connecting several ADS8598 on same parallel bus

Cyril Rupf
Prodigy 10 points
Part Number: ADS8598H

Hi,

I would like to connect 2 ADCs on same parallel bus. In datasheet, one sentence is not clear/strange for us:

"7.4.2.3.1 Parallel Data Read

For applications that use multiple devices in the system, the CS and RD input signals must be driven separately."

So is mean that we need 2 CS and 2 RD lines ?

So the ADC is active if the RD line goes low even if CS is high ?

Before reading this sentence, I was thinking to connect all inputs together expect the CSs.

Do you have a reference schematic for multiple devices ?

Thanks for your help,

CYril Rupf

  • 0
    TI__Guru**** 171005 points

    Hi Cyril,

    Sorry for the delay!  We'll check out if RD needs to be separated.

  • 0
    TI__Mastermind 18900 points

    Hi Cyril,

    I've gotten this question a couple of times and I agree it is confusing. I would have separate CS lines and tie RD/SCLK lines together for multiple devices. So, 3 devices would be 3 CS lines and 1 RD line. They just need separate control for each individual device but CS and RD both need to be active for an ADC data bus to go active. 

    Best,

    -Cole

  • 0
    TI__Mastermind 18900 points

    Hi Cyril,

    As a small follow up, not that it makes sense for your application, there are address decoder ICs (that kind of act like a MUX) that allow 2 or 3 CS lines to break out into 4 or more lines that can be controlled. So, if we had more than 3 devices, we could break out those 3 into 8 different CS lines which would mean we could have 1 RD line and 3 CS lines for 8 devices.

    Best,

    -Cole