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Convert 4-20mA to 0-5v using RCV420

Aziz Jiwani73301
Prodigy 80 points
Other Parts Discussed in Thread: RCV420

Hi,

Need help. I am using RCV420 to convert 4-20mA to 0-5v. For testing I have got a calibrator which +mA and -mA lines and gives me precise 0-20mA output. I have few questions regarding RCV420 circuit

1. As the calibrator is self powered, how do I connect the output of calibrator i.e., +mA and -mA to RCV420 input?

2. Can this IC be used with single power supply, say +15v only. In this case what all changes needs to be incorporated in the circuit (in comparison to the circuit mentioned on the datasheet of page 5 (fig 1))?

Waiting for the inputs.

Thanks

Aziz.

  • 0
    TI__Mastermind 27715 points

    Hello Aziz,

    Thank you for your interest in the RCV420.

    1. As the calibrator is self powered, how do I connect the output of calibrator i.e., +mA and -mA to RCV420 input?

    Wire the circuit as follows:

    • Connect mA+ from the calibrator to pin 3 of the RCV420.
    • Connect mA- from the calibrator to GND.
    • Connect pin 2 of the RCV420 to GND.
    • Leave pin 1 of the RCV420 floating.

    2. Can this IC be used with single power supply, say +15v only. In this case what all changes needs to be incorporated in the circuit (in comparison to the circuit mentioned on the datasheet of page 5 (fig 1)?

    The RCV420 is not a rail-to-rail output amplifier, so it requires a negative supply rail of at least -1.5V in order for the output voltage to reach 0V. It is perfectly fine to provide an asymmetric supply voltage, for example, +15V and -1.5V.

    Best regards,

    Ian Williams
    Linear Applications Engineer
    High Performance Linear

     

     

  • 0 in reply to Ian Williams
    Prodigy 80 points

    Thanks Ian for the solution. The system worked and I am getting the correct readings. 

     

    I had one more question

    1. Is there any way to use both +mA and -mA, so that the input is isolated?

     

    Waiting for your  input.

     

    Thanks

    Aziz