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ADS1261-Q1: Two ADS1261-Q1 in parallel.

Sudesh Bhar
Prodigy 60 points
Part Number: ADS1261-Q1
Other Parts Discussed in Thread: ADS1261

Tool/software:

Hi Team,

I am planning to use two ADS1261-Q1 for my application. I will using the provided SPI interface. There is Master microcontroller and 2 slave ADC connected on same bus. I am running low on microcontroller pins so I would like to use as less pins as possible for my for SPI communication.

These ADCs have SCLK, DIN,DOUT/DRDY_ADC,DRDY as common. For chip select CS I have provided dedicated GPIOs.  I have doubt with regards to DOUT/DRDY and DRDY pin. Can I not use DRDY pin and still get data conversion done or data ready indication by using DOUT/DRDY pin. I want to use DOUT/DRDY pin for both getting the data ready indication and Data output as well. I want to know how differently it will be in implementation when compared to using dedicated DRDY pin.


 



Can you provide me some reference circuit diagram or notes for interfacing two ADS1261-Q1 on same SPI bus. 

One more question. I am not working with differential signals. I am working with single ended signals which Have same ground reference as AVSS. Do I need to set the Analog input (AINN) in register for using it as AVSS ground reference or I shall directly connect to (AINN) terminal or pin to AVSS with trace on PCB.

Thanks & Regards 

Sudesh

Inspecity Space Labs
 

  • 0
    TI__Guru 52146 points

    Hi Sudesh Bhar,

    We don't have a reference design that specifically shows how to connect two ADS1261's together. But the setup you described seems correct. I'd recommend that you get two ADS1261EVMs and actually try it out in your system if you want a quick way to test this. You would have to write your own firmware to control the EVMs because the existing GUI does not support controlling more than one device at a time. But at least the hardware would be readily available to you

    You can use the combined DOUT/DRDY signal from one ADC as the DRDY indicator for both ADCs, assuming you are using the same data rate for both and both ADCs start conversions at the same time.

    Sudesh Bhar said:
    am working with single ended signals which Have same ground reference as AVSS. Do I need to set the Analog input (AINN) in register for using it as AVSS ground reference or I shall directly connect to (AINN) terminal or pin to AVSS with trace on PCB.

    Yes please connect at least one analog input to AVSS so you can measure with respect to AVSS. The ADC always measures between the channel you select for MUXP and MUXN. The ADC converts the voltage difference these channels e.g. VIN = V_MUXP - V_MUXN. 

    -Bryan