Hi,
We have a self-powered DAC161S997 design connected to DS8500 HART modem. We facing problem we think it has with FSK-out filtering.
I'm being confused between the DAC161S997 datasheet and the dac161s997evm schematic regarding the HART and C1, C2, C3.
And even the AC decoupling capacitor to C2. I can find deffirent values in the datasheet. What values are recumended for HART?
In DS8500 it is recumended to have a decouplig capacitor on the FSK_out anything greater than 20nF. But you have 6.8nF.
In our design we used c1,c2,c3 390nF, 220nF, 1nF respectevly. and even the 6.8nF capacitor and a 1uF capacitor on the FSK_out as you can see in the schematic.
Now we have issue that the HART communication does not working and we receive incorrect messages or data.
We tried to remove the 6.8nF capacitor and get same result.
One more confusing thing in the dac161s997evm schematic is that the HART_RX & HART_TX. Are they jumpers or connectors?
Bacause pin 2 in these are connectet together. And is R11 needed for HART
Thanks in advance