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PGA112 calibration

KATYA Asparuhova
Prodigy 10 points
Other Parts Discussed in Thread: PGA112

Hi,

I use programmable gain amplifier PGA112. The calibration function does not work. All 4 CAL functions measure "0" at the PGA out. Please, help me to calibrate the system.

Katya

 

  • 0
    TI__Guru 62765 points

    Hi Katya,

    Could you provide more information about your system including a schematic showing all input, output, and power circuitry?  Information about the application of the PGA112 may help as well.

    The CAL functions require the user to place the ADC REF voltage on the CH0/VCAL pin of the PGA.  If you look at the circuit diagram in the datasheet, the CAL1 output is always GND (or "0"), CAL2 is a 0.9 * VCAL, CAL3 is 0.1*VCAL, and CAL4 is the VREF voltage.  Therefore, if you connect the CH0/VCAL pin to GND and also have VREF connected to GND then this may explain why you only read "0" for any of the CAL outputs. 

    Can you try configuring your circuit in a similar manner as shown in Figure 73 or 74 in the datasheet and see if you achieve the results in shown in the table?

    Regards,
    Collin Wells
    Precision Linear Applications