Hard dV/dt Test

Another test that I have found always brings out the inherent weaknesses of the part is the hard dV/dt test. Basically, I simply slam the red banana plug into the already-powered-up DC bench power supply and look for overshoots (voltage or current) in the switcher. There is a fair amount of natural input bounce created by this rather unofficial test, but that can really help aggravate/expose any startup logic issues with the IC. Of course we may later decide to specify a smooth (non-jittery) input AVI At for the IC and just move on. My colleague used to use a mercury switch for the same purpose. That gives almost the same hard input AV At, but without all the bounce. 

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