LTC2984 - control of ADC1, ADC2 and ADC3 configuration...

Question

Can I setup the LTC2984 to simultaneously measure two devices in 4-wire mode with a shared sense resistor? I would like to connect the sense resistor to ADC1, device 1 connected to ADC2 and device 2 connected to ADC3.is there a way that I can configure this for simultaneous measurement rather than the standard cascade measurement? 
 
 Or, is there a way to configure both ADC2 and ADC3 to connect to and measure the same device (redundant measurements)? 
 
 In what specific setup cases is the ADC3 used? 
 
 Jonathan

KSMendoza · Accepted Answer

Hi JCheney , Unfortunately, there is no way to configure the three channels of the ADC so that you can use them all simultaneously in your desired application. The ADCs are configured depending on the type of sensor you're trying to measure. If you're trying to measure using a resistive element, 2 ADCs will simultaneously sample, one for the temperature sensor and another for the sense resistor. If however you're trying to measure using a thermocouple and you're using a resistive element to determine the temperature of the cold junction, the 3 ADCs will sample simultaneously. One for the voltage induced by the thermocouple, another for the temperature sensor for the cold junction compensation, and the last for the sense resistor. I hope I was able to answer your question. Regards, Karlo

KSMendoza · Answer

Hi Jonathan, All the three measurements are external to the IC. However, I don't think you'll be able to sample 3 different temperature sensors simultaneously as the part just wasn't designed to do that. For example, if you configure the unit to read a thermocouple and you use a thermistor or RTD for the cold junction compensation, one of the ADCs will be dedicated to measuring Rsense, which means it will affect the other two measurements (i.e. thermocouple, and resistor element channels). 
 Regards, Karlo

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LTC2984 - control of ADC1, ADC2 and ADC3 configuration...

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