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Acquire 4-20mA signal with RCV420

Edgar Cabana Vilchez
Intellectual 310 points
Other Parts Discussed in Thread: RCV420, MAX232

Hello, I'm thinking to use the RCV420 to acquire a 4-20mA signal.

Firts, this is my transmitter: http://www.prelectronics.com/idd956.asp?pcol=5333A, this transmitter has only 2 wire for the loop and the power supply and its supply voltage is 8-35Vdc, What is the correct connection between the transmitter and the RCV420?

Second, Can I use the max232 to give negative supply to the RCV420?

Finally, Is necessary that I give +10V to the 16 pin and -10V to the 4 pin?,  Do these values affect in the output voltage?

Thanks.

  • 0
    TI__Guru 63205 points

    Hello Edgar,

    My apologies for the delay on this response.

    Please see the diagram below for the correct connection to the RCV420 with a 2-wire 4-20mA sensor. 

    The RCV420 requires power supply connections to properly operate.  The datasheet specifications were created using a supply voltage of +/-15V.  The minimum required supply connections for proper operation of the RCV420 are:  -5V - +11.5V.  Therefore the minimum negative voltage is -5V and minimum positive supply is 11.4V.  Max supply connections are +/-18V.

    Although you could use the MAX232 to create the negative supply for the RCV420, the charge-pump output of the MAX232 is really designed for digital circuitry and may cause issues with the analog circuitry due to the noise.

    Please let me know if there are any additional questions.

    Thanks and Regards,
    Collin Wells
    Precision Linear