Cyrus, We are working on a reference design dedicated to Foundation Fieldbus, the main source of difficulty / delay with respect to when these devices released has been regarding the FF stack itself, as we did not previously have a FF stack. Right now we're pretty close to having a working / complete stack, and are making some adjustments to the hardware to enable continued progress on that reference design. We're hopeful to have something early next year. The DAC874xH is essentially only providing the encoder and decoder functionality required for the Manchester Encoded waveforms used in Foundation Fieldbus. The rest of the physical layer for controlling the loop current etc. are assumed to be external components. In a lot of ways, Foundation Fieldbus transmitters look very similar to 4-20mA / HART transmitters. We produced a reference design using discrete components for a HART enabled 4-20mA transmitter called TIDA-01504 which you may be able to leverage as a starting point. In Foundation Fieldbus of course there is no need to have a dynamic DC current value, so you could conceivably replace this piece with a static bias voltage. Alternatively, perhaps having the programmability is valuable to leverage for different sensors which may require different quiescent current values on the loop. Also when comparing versus TIDA-01504 the filter component values and gain setting resistors would need some modification in order to fit into the FF requirements, but for the most part I believe HART versus FF/PA can be facilitated through a BOM change. We will also publish a reference design on that topic pending the FF certification completion.
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