EXCITATION CURRENT SOURCES for LTC2984

Hi Team, 

How many EXCITATION CURRENT SOURCES are there in LTC2984?

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  • +1
    •  Analog Employees 
    on Oct 28, 2020 7:38 PM 1 month ago

    Hi ,

        There are multiple configurable current sources (current DACs) in the LTC2984 - however, typically only one is active at a time based on the channel configuration. 

        Cases where more than one current source is active:

    1) Thermocouple open-circuit detect uses a separate current source  from the one used by the cold-junction compensation sensor (Thermistor, RTD, or Diode) - those are active at the same time during the conversion.

    2) 3-wire RTDs use two matched current sources applied simultaneously to cancel the effect of the sensor lead resistance.

    Hope this helps, 

    -Logan

  • Hi Logan,

    Thanks for the information.

    Typically only one is active at a time--> I understood this point.

    You told that, there are multiple current sources in LTC2984--> I just want to know how many configurable current sources are there in the device?

    For an example if I want to connect 3 types of RTD(PT500, PT100, PT1000) means I need to configure three different types of IDACs for each type. For this kind of purpose I am asking the number of configurable current sources.

  • 0
    •  Analog Employees 
    on Oct 29, 2020 4:42 AM 1 month ago in reply to Sarumathi R

    Hi

         The excitation current setting is part of the channel configuration. By specifying the type of sensor (RTD), the connection (2, 3, or 4-wire), and the excitation current, the LTC2984 will configure the IDAC appropriately. They are reconfigured based on the channel configuration word at the beginning of each conversion - there is no setting for the IDAC separate from the sensor configuration. 

        If you have not done so already, please download and play with the TestBench GUI (Demo Software) here: https://www.analog.com/en/products/ltc2984.html#product-requirement - you do not need the evaluation kit hardware to configure channels and view the 32-bit channel configuration word.

    -Logan

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  • 0
    •  Analog Employees 
    on Oct 29, 2020 4:42 AM 1 month ago in reply to Sarumathi R

    Hi

         The excitation current setting is part of the channel configuration. By specifying the type of sensor (RTD), the connection (2, 3, or 4-wire), and the excitation current, the LTC2984 will configure the IDAC appropriately. They are reconfigured based on the channel configuration word at the beginning of each conversion - there is no setting for the IDAC separate from the sensor configuration. 

        If you have not done so already, please download and play with the TestBench GUI (Demo Software) here: https://www.analog.com/en/products/ltc2984.html#product-requirement - you do not need the evaluation kit hardware to configure channels and view the 32-bit channel configuration word.

    -Logan

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