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ADS1260: Procedure and speed when switching analog input

user6519256
Prodigy 20 points
Part Number: ADS1260

Currently, I would like to acquire digital data obtained by converting analog inputs from AIN0 to AIN3 with ADS1260 in order (at the same time as possible).
I have a question about the procedure and speed at that time.
About the procedure
 The procedure is as follows, is it correct?
 1. Wait for DRDY to go low
 2. Enter High for START
 3. Set MUXP to AIN0 and MUXN to AINCOM with WREG Command (AINCOM is connected to GND)
 4. Wait for DRDY to go low and get the conversion data with RDATA Command
 5. Set MUXP to AIN1 and do the same as 3 and 4.
 6. Set MUXP to AIN2 and do the same as 3 and 4.
 7. Set MUXP to AIN3 and do the same as 3 and 4.

About speed
 How long does it take for each piece of data to be acquired while switching the target of the analog input for acquiring digital data as described above?
 Is it 25us because it is 40kSPS? Or is the 179us described in the Conversion Latency of the data sheet the fastest?
Also, if there is a setting / procedure that can be acquired earlier than the above procedure, it would be helpful if you could let me know.

Thank you.

  • 0
    TI__Mastermind 34921 points

    Hi User,

    Yes, your procedure for multiplexing through channels and reading data is correct.

    The conversion latency is quantified in Table 8 in the datasheet, and is a minimum of 179us as you mentioned. It should be noted that Table 8 quantifies the time it takes for one conversion on one channel. If you were to take multiple measurements on the same channel, then you would see reduced conversion times.

    For example, if you were sampling at 40 kSPS, the first conversion would take 179us as shown. The second conversion would take ~1/data rate, or 25us. The third conversion would take 25us as well, as would the 4th, 5th, 6th, etc. However, as soon as you switch input channels, the latency in Table 8 applies again.

    So for your system, it will take 179us minimum per channel to cycle through the inputs since it appears you are only converting once per channel.

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 20 points

    Hi Bryan

    understood
    I was saved because I was not confident in reading the data sheet

    Thank you