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OPA211: OPA211IDGKT Maximum AC Output Current Question

Dominick Lauria
Prodigy 10 points
Part Number: OPA211

Tool/software:

Hello,

Texas Instruments ticket number CS2703458 had discussed a question that I had regarding the maximum AC output current of part number OPA211IDGKT.  Some back and forth discussion had occurred within the ticket until I was referred to posting the item that I need clarification on right here to this forum.

Here are the latest questions that I had posted to the ticket that I need help with:

1)   I am not convinced yet based off the information that was provided to me in ticket number CS2703458 that I am off the hook with not having to worry about the maximum AC current that the OPA211IDGKT op amp can deliver to a load.  The AC frequency range that I plan to drive a load at can be anywhere from 500Hz to 10kHz in my application.  Currently in my design, I have a load resistance value equal to 182.9 Ohms that the output of the OPA211IDGKT connects to.  The OPA211IDGKT is receiving + and – Vcc with +15V and -15V DC power sources.  Assuming that the maximum output voltage that the OPA211IDGKT can apply to the load resistance in this case is equal to 15Vp, this results in 82.01mAp of current traveling through the load resistance.  Can I comfortably apply a 15Vp voltage (anywhere from 500Hz to 10kHz) from the output of the OPA211IDGKT to a 182.9 Ohm load in this case on a continuous basis without causing any damage to the op amp?

2)   The OPA211IDGKT datasheet shows a maximum output current value of 30mA.  Is this 30mA DC?  The previous question presents a scenario where 30mA is exceeded because I am driving 82.01mA of peak AC current to a load which is why red flags have been raised on my team and help from Texas Instruments is needed.

Thank you in advance for providing us with clarification on our concerns.  The datasheet did not make it obvious for us.

  • 0
    TI__Genius 16615 points

    Hi Dominick,

    The OPA211 could source about 30mA as you mentioned. Figure 37 highlights the output voltage vs output current for this device. If you were to pull continuous current, the concern is not only its ability to source this current but also the junction temperature as the device heats up. For any given device, if the output current highlighted in the datasheet is X, excluding any other performance limitations such as junction temperature, it should be able to source X current at the peak of an AC signal. For the application you highlighted, the device would not be able to source the amount of current required in your application. Could you share any additional performance requirements to try to find a device that could fit your application.

    Best Regards,

    Ignacio

  • 0 in reply to Ignacio Vazquez Lam1
    Prodigy 10 points

    Hello Ignacio,

    Thank you for the detailed input that you have provided to us.  Your reply provides a lot more clarity behind the current and temperature limitations of this particular op amp and has been found to be helpful to us.  Since I have some control over the load resistance that this op amp drives, I am going to try to adjust that area of the design so that this op amp can be used within its specification.  I am less willing to change the part number of the op amp that is currently being used in the design.  Thank you for highlighting the definition of maximum output current shown in the datasheet for an op amp.

    I am going to mark this item as resolved.  If we have any future needs, we will reach out.  Thank you for your time and helpful insight.

    Dominick