I have the attached circuit as a Voltage Controlled (V_Control) Current Source (I-Load).
This circuit has an stability issue. When V_Control drops from 3.3 V to 0 volts the circuit works fine at room temperature. But when the temperature is reduced to -45 degrees, it starts to oscillate.
I cant figure out why? Possible causes are:
The output waveform (U89 is the LT1013) at room temperature is:
The output at -45 degree C is:
Please let me know if you can advise on the source of oscillation here.
Hi kaveh14934: If you look at the INA193 data sheet, its CMRR range over temperature is "12V to 80V". So it does not include ground. In your circuit, when the command is to go to zero current, the input CM to the INA193 drops to ground. I think that could be the problem.
To fix that, you might replace INA193 with LT6105 or LT1789.
The input CM range is -16V to +80 V as I can see in the datasheet.