Possible Short in Current Loop between DAC161S997 and HART FSK


Thread Starter

Sruthi uk

Dear friends,

I have measured both the loop current from DAC161S997 and HART FSK output from HART modem AD5700 and make sure that they worked properly. I am trying to interface the DAC circuit with HART modem for getting the HART FSK signal from DAC IC along with the loop current by using a 250ohm in series with 24V supply as shown in below schematic.

But now the IC is getting heated when the 3.3V power supply is given for DAC161S997. The SPI read from DAC is not correct. Also a 66 ohm is measured across the VA AND COMA using multimeter. There is no such internal resistance shown between VA and COMA in the DAC161S997 datasheet. Is this a short?

What may be the reason for the DAC ic by getting heated? Is there any solution for avoiding this?

With Regards
Sruthi uk