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ADS4122: Interfacing high speed ADCs to Microcontroller

Part Number: ADS4122
Other Parts Discussed in Thread: THS4541, TIDA-00942, OPA656

Hi all,

I am working on a project in which I need to sample and convert a 1.5MHz signal. I was hoping to find a microcontroller with a built-in fast enough ADC for this task but it is very hard to find uC with ADCs capable of more than 5 msps, which is definitely not enough for my application.

I decided then to explore the option of using an external high speed ADC, and based on speed, resolution and cost I found the ADS1422 a reasonable option.

The question I have is whether it is possible to interface a converter like this directly to a microcontroller? I can see that FPGAs are usually employed for this task. I reckon this has to do with the fact that most high speed ADCs provide differential LVDS outputs that microcontrollers cannot interface directly with, but the ADS1422 also provides de option of single-ended LVCMOS output. Is there also a timing issue, e.g., the data valid time at the ADC output? Would a buffer/data latch be needed?

Any help on this would be welcome!

Thanks!

Pablo

  • Pablo,

    I would think most microcontroller could handle a direct interface to this ADC in CMOS mode. In this mode there is an output clock that is centered with the valid data time that could easily be used by the micro to latch data. Just make sure the micro can handle 1.8V CMOS level signals. If not, you would need to use a voltage translator device.

    Regards,

    Jim

  • Pablo,

    Please have a look at the following TI Design TIDA-00942 that was just released. It shows a DC coupled 20Msps digitizer which uses the ADS4122+THS4541+OPA656 - its basically a low cost 20Msps scope front end. This cape connects to the BeagleBones Black as the capture platform.

    www.ti.com/.../TIDA-00942

    Ken
  • Ken,

    Much appreciated for your answer. Exactly what I was looking for.

    Thank you!

    Pablo