Hi, my first post, I am using this circuit to control a 4-20ma from my Arduino Due, the DAC0 is now damaged and not producing any voltage, DAC1 is a spare and is still functioning. There are 2 x 12v supplies in the design, I noticed the Gnds are mixed up with the GND on C45 should have been IGND. Is this the reason for the failure on DACO and should I have some sort of protection before the LM358 op amp? Any help would be greatly appreciated

 

Nobody is going to open that file, sorry. Opening a word document some stranger posted on the internet is like using a needle you found on the street to inject insulin. If you want help, post a picture or a PDF.

 

Hi, sorry about that, the circuit was working for 3 months and was scaling perfectly with R47 a precision resistor of 137 ohms.

 

 

Hi, my first post, I am using this circuit to control a 4-20ma from my Arduino Due, the DAC0 is now damaged and not producing any voltage, DAC1 is a spare and is still functioning. There are 2 x 12v supplies in the design, I noticed the Gnds are mixed up with the GND on C45 should have been IGND. Is this the reason for the failure on DACO and should I have some sort of protection before the LM358 op amp? Any help would be greatly appreciated

What does your datasheet for the Arduino say about absolute maximums regarding your DACs? Normally, the concept is called 'signaling'. 'Signals' per se, are about voltage, not current, your DAC output should be really low current into the OpAmp, allowing the OpAmp to do the heavy lifting.

 

What does your datasheet for the Arduino say about absolute maximums regarding your DACs? Normally, the concept is called 'signaling'. 'Signals' per se, are about voltage, not current, your DAC output should be really low current into the OpAmp, allowing the OpAmp to do the heavy lifting.

 

Hi, thanks for your reply. The absolute maximum is 3ma, I cut the track on Dac1 and checked the current draw, it was reading very minimal, I used a 250 ohm resistor on the output as the load.