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OPA992: OPA992S OUTPUT QUERY

Part Number: OPA992

Hi,

I'm using the OPA992s 6-pin amplifier as a buffer amplifier. The Power inputs are +12V and -12V. And the input range is +10V to -10V. We are giving the Shutdown signal around 20mV still the output of opamp is not getting. please check my circuit diagram and let me know what is the issue.

  • This device has no ground pin. The shutdown signal must be referenced to V-. You want a level shifter; a transistor might suffice.

  • Hey Tejendra, 

    We are giving the Shutdown signal around 20mV

    Does this mean 20mV is applied to "AXIS6_MOTOR_SERVO_EN"

    Here is the description from the datasheet section 6.3.11:

    Amplifier enabled (shown in green) happens at (V-) and (V-) + 0.2V, with the power supplies in the image, this would happen between -12V and -11.8V. 
    Amplifier is disabled (shown in yellow) happens at (V-) + 1.1V and (V-)+20V, with the power supplies in the image, this would happen between -10.9V and 8V.  

    All the best,
    Carolina

  • Hi Clemens,

    As per the datasheet, the IC has an internal 100KE pull down to -12V if we are not going to use the Shutdown pin. But in our case, it is not working without an external pull-down. What may be the issue?? 

  • According to the schematic, you have an external pull-up. The internal pull-down can work only if pin 5 is left open.