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SPI daisy-chain-compatible compact multi-channel ADC needed

Hannah Stuart
Prodigy 10 points
Other Parts Discussed in Thread: ADS8684

I'm incorporating sensors into a robotic finger. The microcontroller in the palm has 4-wire SPI capabilities but doesn't have any extra I/O pins available for separate slave-select lines; I need Daisy-Chain communication between ADCs on various phalanges/fingers. We are tight on space, so a 4-channel (or more) IC with high analog input impedance/buffers incorporated would be ideal to reduce the number of components. Resolution is less important than sampling speed.

I found the preview datasheet for ADS8684 and it seems just right. Is there an alternative ADC chip that might fit my application?

Also, if an ADC chip does not specify that it has a Daisy-Chain mode is there any way to implement daisy-chaining anyway? Somehow access the I/O shift register directly when the SS pin is not active to pass-through messages?

Thanks!

  • 0
    TI__Guru* 92715 points

    Hannah,


    There are quite a few devices that have some sort of daisy chain mode, but I'm not sure the others would be any better for you application than the ADS8684. It might help to limit some of these choices if you describe some of your system requirements. In particular, do the ADCs need to be 12 or 16 bits? What data rate do you need to read? How many channels do you need for your entire system? Are your inputs single ended (referenced to ground) or fully differential?


    Joseph Wu