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4-20mA (current signal) receiver design support

Category: Hardware
Product Number: AD74413R

Hi, 

We’re looking to use the AD74413R IC to receive 4-20mA signals from a sensor/transmitter. Kindly share your comments on the following queries:

  1. If the current loop is powered or a 2-wire loop, will we need to provide 24V to the AVDD?

  2. Is it possible to mix 2-wire (loop-powered) and 3-wire/4-wire loops on the same IC? What design considerations should be taken into account for this configuration?

  3. In a 2-wire loop system, is it possible for the device(s) on the loop to be powered from the AVDD supply? 

Thanks

Mukesh

  • Hi  ,

    1. If the current loop is powered or a 2-wire loop, will we need to provide 24V to the AVDD?

      AD74413R always need AVDD power supply for it's operation. However, channel function can power up the sensor in "Current Input Loop Powered" mode/function. If sensor have it's own power "Current Input Externally Powered" mode/function should be selected. Note, AD74413R does not have integrated function to operate as "Loop Powered DACs", where it can receive power from the loop. 

    2. Is it possible to mix 2-wire (loop-powered) and 3-wire/4-wire loops on the same IC? What design considerations should be taken into account for this configuration?

      From perspective of using AD74413R, there should be no problem in 3-wire or 4-wire loops on the same IC. Only make sure that channel is configured to correct channel function as "Current Input Loop Powered" for 2-wire loop powered and 3-/4- use "Current Input Externally Powered". Creating module with 3-/4-wire loop powered features is domain of the power supply solution and "out screw terminals" configuration. All these modes should be possible, considering that I/ON_x terminal is connected to AGND, which can serve as return path for power in 3-wire loop powered configuration.

       

    3. In a 2-wire loop system, is it possible for the device(s) on the loop to be powered from the AVDD supply

      As already described above, please use "Current Input Loop Powered" mode/function. This provides power to the loop from AVDD onto the channel (I/OP_x screw terminal), loop current limit is configured by DAC.If your question is concerning the 2-wire system and sensor is already having power from the field, please use "Current Input Externally Powered" mode.

    Feel free to come back to me, if you would need any clarification on the same. And let me know, if I understood your queries correctly and answered them. 

    Regards,

    Arnost