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DAC8740H: Using the DAC8740H with the XTR116

vikesfan
Prodigy 170 points
Part Number: DAC8740H
Other Parts Discussed in Thread: XTR115, , XTR117, XTR116

In your reference design for the DAC8740H family devices, I see you use separate a op amp, regulator, and voltage reference for the 4-20mA driver portion of the circuit.  I am curious why this approach was taken instead of using an XTR115/116 device which combines all three of these elements in one IC.  Is there some aspect of the XTR115/116 device that would cause a problem for the DAC8740H to create a HART compatible 2-40mA interface?

Also, the 8740 uses a UART interface, the 8741 uses a SPI interface, and the 8742 can be configured for UART or SPI but other than that all three parts seem identical.  Is it recommended that a new design use the 8742 for long term availability?

  • 0
    TI__Mastermind 46290 points

    Hello,

    First I'll provide the simplest response - the entire DAC874xH family was developed in parallel just with some staggered release. Otherwise the parts are completely identical and there are no concerns with respect to availability.

    The reason we chose a discrete approach in the reference design was essentially to have the flexibility to experiment with different discrete components as this was our first official HART certification, in terms of DAC output bandwidth, loop current controller bandwidth, and power-supply solution. I have no reason to believe that the XTR115/XTR116/XTR117 would not be acceptable.