On Sat, 8 Apr 2017 21:43:31 +0200, you wrote: >Am 08.04.2017 um 17:52 schrieb David: >> >> If they are not being tested, then where is the maximum specified >> leakage number coming from? For a small signal bipolar transistor it >> will typically be 25nA, 50nA, or 100nA, but the InterFET datasheet (1) >> shows 10pA maximum and 1pA maximum for the A versions. > >The large print giveth and the small print taketh away. > >Usually there are footnotes and weasel words like "sample tested", >"by characterisation" or "not production tested". >The time such a small device sits on the wafer tester costs much more >than the silicon. For 100 msec. >At 1 pA it takes an eternity until the capacitances in the setup >are charged. Just the waiting time makes such a diode or FET >a premium part.
Low leakage is the defining characteristic of these JFETs so they better be testing them. The Calogic datasheet was the only one I checked which said anything like "For design reference only, not 100% tested" and it did not apply to the leakage current. The non-A parts are only tested down to 10pA. >Back to input protection: > >Someone in the sci.electronics.design group mentioned these >< https://www.digikey.de/products/de?keywords=cmpd6001s > >but, as usual, typical values, and watch the plot with the temperature >as parameter. At least they are cheap. I think these were pointed out to me before. Since I would have to test them to guaranty leakage below 500pA, I might as well test a cheap small signal transistor. If you want a laugh, take a look at NXP's various "low leakage diodes"; they only specify and test them down to nanoamps. But I assume for most new EEs that *is* low leakage. >Also interesting, while not exactly low leakage diodes, are these >USB3 lightning arrestors: >< https://www.digikey.de/products/de?keywords=296-25509-1-nd > >Looks like they don't spoil the timing. > >regards, Gerhard USB is not leakage sensitive. It looks like these were only tested to the same 100nA standard as many transistors which makes sense; they just need to weed out bad parts. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
