[time-nuts] Low CostTemperature sensor
csteinmetz at yandex.com
Tue Jan 17 04:17:25 EST 2017
> That article has a major error. Anyone know what it is?
Well, the author says the reverse current of a diode is "directly"
proportional to temperature. This could suggest that he means the
relationship is linear (the relationship is actually exponential with
absolute temperature). But that's not really an *error* -- just sloppy.
"Direct" does not necessarily imply "linear." An exponential
relationship is "direct" in the sense that it is what mathematicians
call "injective" (every temperature corresponds to exactly one value of
Then, in discussing the LM95235, he says that it can use the
"collector-emitter junction diode" of a transistor as the sense element.
Of course, a bipolar transistor has no collector-emitter junction.
His diagram correctly shows a diode-connected NPN operating in the
active region (forward biased, not reverse biased as the rest of his
article discusses) as the sensor for the LM95235.
Are any of these what you had in mind, or is there more?
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