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RCV420: Datasheet calculations

Kavita Prya
Prodigy 15 points

Part Number: RCV420

Tool/software:

Hi everyone,

I'm thinking of using the RCV420 for my application. It will be used to convert the signal of a RTD measuring converter(4mA to 20mA) to a 0V to 5V or 0V to 3,3V. However when reading the theory of operation in the DS I noticed 16mA being used for the calculations. Can someone explain the reason for this?

Thanks in advance.

Kind regards,

Kavita

  • +1
    TI__Guru 55466 points

    HI Kavita,

    Below is an approximate TINA simulation of the data sheet recommended circuit of Figure 1. 

    The simulated circuit of Figure 1 produces 0V-5V output for a 4-20mA input signal.

    The reason the gain is calculated by dividing the voltage by 16mA, is because the output span current is between 4mA to 20mA, or essentially 16mA:

    V_OUT / I_IN = (5V - 0V) / (20mA - 4mA) 

    V_OUT / I_IN = 5V / 16mA

    V_OUT / I_IN = 0.3125V/mA.

    Please let me know if this answer your question or if you require further assistance.

    Thank you and Kind Regards,

    Luis

    Attached is the TINA simulation:

    RCV420_3-31-20_standard.TSC

  • 0 in reply to Luis Chioye
    Prodigy 15 points

    Hi Luis, 

    Thank you for your reply. 

    This cleared things up, sadly I will not be using this part as it is not in stock anywhere.

    Í will try to make a TIA with the same specs. 

    Kind regards,

    Kavita