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Choosing the right ADC for the job

Question asked by Craio on Apr 23, 2014
Latest reply on May 1, 2014 by Craio

So i'm trying to decide on the correct adc to use in the following application: read the analog output of up to 3 scientific grade sensors with  analog out (offcourse). voltage ranges between 0 and 5V (some are up to 5V others up to 3 etc) and one RTD with accuracy of 0.01°C.

 

So far i've identified the following requirements:

(multiple adc's allowed)

- 4 differential inputs (3 for generic sensors and one for the RTD)

- Atleast 14bits without noise/errors  (that's the minimum accuracy required to use the sensors at maximum accuracy)

- Built in current excitation source is handy

- speed is of lesser importance, outputrate will be 10Hz max so 50SPS is plenty (incase oversampling is required)

- i'm new to adc circuit design, so 'recommended schematics' in the datasheet are a plus

- can be soldered by hand

 

The ADC(s) will be connected to a microchip dspic with multiple SPI interfaces.

 

Based on the above i've so far chosen these ADCs:

AD7176-2 and AD7713

The first one seems a low noise easily interfaced and with few external components ADC.

The second one is harder to interface and more external components but has the current sources and a AIN suited for 4m-20mA interface (which might come in handy).

 

So I would put one of each on the PCB. (Not 2x AD7713 because of the price and more external components).

Is this a good choice? Or would you recommend other ADC's?

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