Electronics > Projects, Designs, and Technical Stuff

24-Bit Instrumentation ADC Recommendations

<< < (4/4)

Gibson486:

--- Quote from: nctnico on September 09, 2019, 09:17:13 pm ---
--- Quote from: geo_leeman on September 04, 2019, 02:52:36 pm ---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).

--- End quote ---
I've used the ADS1216 for one of my designs. The downside with all these ADS12xx converters is that they need several consequtive samples on the same channel for the internal filters to work so the effective samplerate drops a lot quickly. IIRC I got to something like 100SPS for 5 or 6 channels. They are also not so nice to interface / control.

Ofcourse the surrounding design needs a lot of attention as well to keep noise out and get rid of stray currents which may cause an offset.

--- End quote ---

I have used that chip before. Usually multiplexed (greater than 4) ADCs are a pain to talk to. When you finally get it working though, they are great.

amspire:
There is Avia Semiconductor's HX711 24 bit sigma delta A/D used in many of the weight scales. The cost is 56c in one off quantities or 35c for 1000 quantities from LCSC.

It measures at either 10 or 80 samples/second, has differential inputs of either +/-20, +/- 40 or +/- 80 mV (it is designed for bridge circuits). It includes a regulated supply for driving a bridge circuit. It has built in 50 and 60hz rejection.

There is no linearity spec. On the +/-20mV range, offset drift is typically +/- 6nV per degC and the gain drift is +/- 5ppm per degC.

Common mode rejection of the differential input on the +/- 20mV range is 100dB.

2.6V - 5.5V operation, -40C to 85C. External or internal clock and built in band gap reference.

There are 2 input channels so for 4 channels, you would need two of the chips.

Other 24 bit A/d are the HX 712, 710A, 710B, 710C, 720 and 530B all on LCSC at cheap prices.

The 712 and the 530B specifies an INL of +/- 0.001% of FS. All the chips are built on the same technology, so I would expect them all to have similar performance.

Navigation

[0] Message Index

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod