Tool/software:
Hi :
I am trying to use the OPA188 as high side current sensor .
I am using the TI pspice but the output is not correct :
with Rshunt =10 , R4=R2= 20k , R1=R3=1k , Vout must be : 9ma x 10 x 20 = 1.2v hoever the output is 57.06mv when using bias point simulation .
am i missing something or it is an issue with PSpice for TI not able to simulate the opamp bias points properly ?
Hi Hamze,
am i missing something or it is an issue with PSpice for TI not able to simulate the opamp bias points properly ?
Since the OPA188 is measuring on the high side of current sensing, your input Vcm should be very close to 12Vdc. This violates the input Vcm range per the op amp per your simulation.
The output voltage also has linear operating range, see the table below, so you need to watch for it.
Here is the design parameters that chopper amplifier should be watched for.
If you have other questions, please let us know.
Best,
Raymopd
Hi Harnze,
i am not sure that the input VCM is an issue .
Here is the input Vcm at the input pins, which is 11.384V. In order to keep the input Vcm within the linear operating region, the input Vcm at the pin is from V- (GND) to <10.5V.
In the datasheet, the input Vcm is specified at the input pins.
Please let me know if you have other questions.
Best,
Raymond
