DAC output on Teensy 3.5 and 3.6

Status
Not open for further replies.
S

Skiddy

Well-known member
I have connected the DAC outputs to galvanically isolated 4 to 20 mA converters, which are loop powered. Thus the converter only needs a voltage between 0.5 and 2.5 VDC from the DAC as an input and will control the output between 4 and 20 mA. The measured resistance of the input is 2.7 kOhm. Measuring the output at the DAC's without the converter connected I can generate 0 to 3.3 VDC.

The problem I encounter is, that the voltage levels out at about 1.36 VDC, when the converter is connected, as if the DAC cannot drive more than about 0.6 mA into the input. Can anybody confirm that?
 
Great, thanks for the info. With 1mA max it should be good into 2.7 kOhm though - strange.
 
Most probably, and especially since you say that it‘s galvanically isolated, there is some way of semiconductor involved, for example for current mirroring or something alike. That‘s why the measured 2,7kOhm might be a non linear value... If voltage precision is required, there should always be an op amp as x1 voltage follower between the DAC and whatever load.
 
Thanks,

it is what I suspected and have written to the supplier to ask for conformation.
 
Status
Not open for further replies.
Back
Top