OPA992: OPA992S OUTPUT QUERY

Tejendra varma

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.

10 months ago

0 Clemens Ladisch 10 months ago

Guru 291380 points

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

0 Caro Walter 10 months ago in reply to Clemens Ladisch

TI__Mastermind 20082 points

Hey Tejendra,

Tejendra varma said:
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

0 Tejendra varma 10 months ago in reply to Clemens Ladisch

Prodigy 50 points

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??

0 Clemens Ladisch 10 months ago in reply to Tejendra varma

Guru 291380 points

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

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OPA992: OPA992S OUTPUT QUERY