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THS3120 High Current Pulse Tolerance

Kyle Burk
Intellectual 915 points
Other Parts Discussed in Thread: THS3120, OPA2673

I’m trying to use the THS3120 for a design but am concerned about high current pulses in my system on the output pin.  The datasheet only specifies the continuous output current capability, which is 550mA.  There are two pulses we are concerned about:


First, a 2A pulse over 100us.

Second, a decaying 1MHz signal with the waveform below. 

Will either pulse damage the part?

If it can’t be supported, is there a different device in the portfolio with comparable specs that can support it?  If not is there an additional circuit that could be placed on the output to buffer the signal?

  • 0
    TI__Genius 12631 points

    Hello Kyle,

    It is difficult to predict the long term damage  caused by such transients as it is dependent on the rate at which the transients occur and the ambient temerature.We do not guarantee performance/reliability under such conditions as it varies from customer to customer. You will have to run your own Qual/Reliability tests under these conditions to determine the reliability of the amplifier.

    The OPA2673 has slighly higher output current. but operates at lower supplies. Another thing you can do is "Load Sharing". If you look at Figure 56 of the datasheet you will see the circuit. The advantages to this are two-fold:

    1. The load is shared between 2 devices.

    2. The series output resistance offers added protection from current surges by limiting the output current.

    You mentioned that there are high current pulses on the output of the amplifier: are these caused by some other circuitry that is hanging on the output of the amplifier or is it a signal on the input of the amplifier that then ends up driving the high current transients? Depending on how much head room you need from the amplifier, you can put a series resistance on the output pin of the amplifer that will then limit the current through the amplifier. Can you put the amplifier in power down mode when the transients occur or are the transients unpredictable? Putting the amplifier in power down mode would present a high output Z that would act as protection (if the transients are caused by something hanging on the output line).

    -Samir