Other Parts Discussed in Thread: STRIKE, REG1117, LM317HV, LM317
I am looking for some reference information or recommendations on how to best limit the current of OPA454.
I have an application where I want to do some voltage/current sweeps on some units using a signal generator, a series current sense resistor and a couple of scope probes similar to a curve tracer but in an embedded application. My signal generator is only capable of signals between -5V and +5V and I want to use the OPA454 with a 10x gain that would get me into the +/-50V range.
However, I would like to be able to set a maximum failsafe current limit on the output to a level less than 50mA as a safety check to prevent damage to my DUT. My intended DUTs are actually going to be potentially damaged devices that I want to be able to be able to compare the IV curves of a known good device against a potentially compromised device that has suffered an ESD strike, or other malfunction. I just don't want to create additional damage to a pin if it is unable to sink maximum 50mA output of the OPA454.
I have seen a variety of methods and information on how to create current limit circuits. One method is to limit the current into the V+ and V- supply rails and there are many other methods using a variety of transistor and resistors to create a sense loop to control a pass transistor that could throttle the current flow of the output signal itself.
In the datasheet there is an example of how to increase the output current with an external NPN and PNP transistor. Is there a recommended method for reducing the output current for this device without creating a lot of signal distortion? What other factors do I need to consider and problems I may need to avoid? I haven't done a lot op amp designs more involved than a basic non-inverting buffer with some small amount of gain. If you have any other thoughts and suggestions I would also appreciate those.
Thanks!
Jonathan