I appear to have blown up the THS4271 on the THS4271EVM-UG. It worked very nicely out of the box. Then we removed the 50 ohm input resistor since I'm using it as a high impedance follower When we turned it on, it was drawing 40 ma from the negative supply and the output was stuck to that rail.
I'm wondering if there are any issues with the input protection on that part. Without a low impedance to ground, could the input have gotten zapped by ESD? I suppose I could add protection in the form of a resistance in series with the non-inverting input (<1 K to keep its corner with the input capacitance out of the way). Alternatively, I could raise the value of R4 from 50 ohms to 1.5-2K, which would be high enough to keep from loading the drive signal, but still might be small enough to dissipate any static.
I am running the part off two discrete 5 v supplies, so power supply sequencing could be an issue, but I see from previous posts that it isn't.
Is the part unstable with infinite input resistance and did it burn itself up?
I'll replace the chip and try again, but if someone has seen this type of problem before, I'd appreciate any tips.
