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RCV420: rcv 420 offset

Muhammad Awais
Prodigy 20 points

Part Number: RCV420

Hello everyone!

I am using rcv420 for (4-20mA) current to voltage conversion in this configuration shown in the image.

I am using two different sources one(+-12 V) to power up the rcv420 and other (+15V) to drive current through a variable resistor as my current source. The problem is that I am getting an offset of about 1.25 Volts for 4 mA current and similarly for 20 mA I am getting 6.27 Volts. The output goes zero for 0 mA. Please help me if I am using it correctly or what changes do I need to make in order to null the offset and get 0 to 5 V corresponding to (4 to 20 mA)

Thanking you in anticipation.

Regards,

Muhammad Awais

Student at QAU, Islamabad.

  • 0
    TI__Guru 64935 points

    Hello,

    I suggest you double-check your electrical connections, especially the connection of pin 15 (RCV FB) to pin 11/10 (REF OUT).  This connection is the one that provides the -1.25V offset to the T-network in the feedback loop as described in the "Theory of Operation" section of the datasheet.