Electronics > Projects, Designs, and Technical Stuff
24-Bit Instrumentation ADC Recommendations
geo_leeman:
I'm working on a project that is using the "blue pill" as the microcontroller (STM32 M0 8 MHz) that reads an accelerometer, four analog sensors, and logs to an SD card. The analog inputs are pressure/temperature and need to be digitized at the highest resolution possible, so I'm using a 24-bit ADC. I started with the ADS1243, but ideally I want to log everything at 10Hz which isn't possible with the ADS1243 as it is 30 SPS max. Even 5 Hz would be pushing it I think with settling time after switching the MUX (say 1 sample settling = 8 sample periods to measure all 4 channels so 30/8 = 3.75Hz). I'm going to be doing some other revisions, so it sounds like an ADC change out is in order. I've been looking at the ADS1217, but was wondering if any of you had recommendations?
I've used some simultaneous high rate ADCs before like the MAX11040K, which seems like overkill here. So to summarize, what's your favorite 24-bit ADC that can sample 4 channels at a minimum of 10Hz each (ideally a bit more so we have some headroom).
Gibson486:
When it comes to ADCs, I use Linear Tech/Analog or TI. For yours, I am sure that Linear tech makes something that could fit the bill...
MagicSmoker:
Hmmm... anything over a native resolution of 18b is exceptionally difficult to implement in practice, especially with a 5V (or lower) reference. After all, the LSB for an 18b ADC with a 5V Vref is a mere 19uV, and for a 24b ADC it will be 300nV. That's probably going to be in the same ballpark as the Johnson noise of the sensor resistances.
OM222O:
ADS1219 / ADS1220
With the built in reference and some basic filtering, I could get them to 10uV accuracy :-+
24 bit SD with a max sample rate of 1KSPS , or a minimum of 20. they also have built in PGAs and some features to correct for offset errors. the ADS1220 has also some more features to detect shorts and whatnot. they're really versatile and I've used them in a lot of projects before.
I think you can get even better results with an external reference, such as those 0 ppm/c ones made by AD, although they cost a hefty penny (about 10$).
geo_leeman:
You know - I've used the ADS1220 before and totally forgot about it! It is really a very nice part. Most of what I do is scientific instrumentation type work, so a $10 reference is nothing compared to the cost of the sensors they are hooking up! I forgot about it going up to 1 ksps as well.
I've got a MUX sitting in front of the ADC as well to connect the inputs to the sensor, ground, or Vref to perform some initial measurements on startup of ground/vref to verify system operation.
Navigation
[0] Message Index
[#] Next page
Go to full version