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THS3121: Short Circuit Protection

Part Number: THS3121
Other Parts Discussed in Thread: THS3491

I'm trying to verify whether or not there is internal short circuit protection on the output of this opamp. We're using it for a pulse per second (20us PW) but there are requirements for short circuit protection.

Currently, we're just limiting the current via a resistor and doubling the voltage output (20Vpeak into a 100 ohm load, 50 of which we are providing in series to limit the current in the event of a short circuit). However, we're running into troubles with rise time due to other factors.

In order to reduce the rise time, we're looking at removing the series resistor and just have the opamp go to 10Vpeak right into the 50ohm load. However, that means there will no longer be the current limiting resistor in series. So I want to know if the opamp can handle that short for short durations or is it not equipped to handle it?

  • Hello Elisha, 

    There are not that many high speed CFA devices that include an active short circuit protect ckt in the output stage - I would surmise the THS3121 does not as there is no mention of short circuit protect in the data sheet, 

    The new THS3491 does have an active protect at about 600mA, and a thermal shutdown as well. 

  • Hi Elisha, 

    As Michael stated above, we unfortunately do not have many parts in the high speed catalog that feature short circuit protection. Typically we expect a load on the device. 

    Regards,