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OPA891: Stability with High Capacitive load & Output Current Limit

KrnB
Intellectual 700 points

Part Number: OPA891

I am considering OPA891 in my design for generating square wave. I understand the output will be distorted when i drive capacitive load.

Please confirm -

  • is the Opamp OPA891 stable while driving capctive load of the greater than 1uF for close-loop gain of 10 considering i place a isolation resistor as mentioned in Figure 7-1. Driving a Capacitive Load' ?
  •  Section 5.6 says output current limit & also says that user to not exceed maximum junction temp. Does this mean that OPA891 is not protected internally against short-circuit current?
  • 0
    TI__Mastermind 22180 points

    Hi,

    I was able to simulate a gain of 10 circuit with a 1uF load using an isolation resistor of 10ohms. Can you share what value you used for your isolation resistor as well as an image of the distortion you are seeing? Could you measure the current demand required in your circuit, there could be a chance the device is current limiting during the rising/falling edge and it is pulling to much current. Regarding the devices output current, we would recommend to keep the device in the limits of what is described in the ABS max table. The device is still susceptible to damage if junction temperature is exceeded even if the current being pulled is not the absolute max the device can output.

    Best Regards,

    Ignacio