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DAC161S997: 4-20mA Receiver and transmitter to RS232

Kai Hsiao
Guru 12675 points
Part Number: DAC161S997

Hi Sir 

I would like to design for 4-20mA Receiver and Transmitter to RS232

System structure as below figure 

May I know does TI have similar reference design can support Transmitter and receiver at the same time 

1. What's disadvantage about discrete solution?

2, May I know discrete solution can modify output current value or just fix 4 and 20mA  only 

  • 0
    TI__Expert 5820 points

    Hi Kai,

    I am not sure exactly what you are looking for or how this would work. Are you trying to design a circuit that converters the DC loop current 4-20mA value into RS-232?

    1. I am not sure how you could do this discretely. RS-232 is a digital communication while the loop current is an analog value. An ADC is needed to sense the loop current and provide the MCU with the digital value. The only way I can imagine this working is by using an MCU with an ADC and RS-232 transceiver. The ADC would convert the loop current and the MCU would use the transceiver to transmit it over RS-232. A similar implementation could be used to convert the RS-232 through the MCU to a DAC that sets the loop current.

    2. A discrete solution to output 4mA-20mA can be accomplished with either an integrated 4-20mA DAC or discretely using a DAC with a V-I conversion stage to set the loop current. DAC161S997 is a 2-wire loop powered device. Is your design for the 2-wire or 3-wire architecture? See the blog below for an overview of these typologies.

    https://e2e.ti.com/blogs_/archives/b/precisionhub/archive/2014/04/29/industrial-dacs-an-overview-of-analog-outputs-and-architectures

    Thanks,
    Garrett