How many EXCITATION CURRENT SOURCES are there in LTC2984?
Hi Sarumathi R,
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,
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.
Hi Sarumathi R,
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.