Analogic output temperature sensors have the disadvantage of long lines
transmision problems ( LM135 and LM335 ). High stability ( 0.1C ) and
precision could be obtained only with a (self) calibrating
algorithm. There is no interchangeability without recalibration ( even
with 10K external resistor ) for resolutions as low as 0.1C.
Digital output sensors are more expensive (DS18s20, DS1820) usual are
working with a resolution of 0.5C ( 0.1 with some tricks ) but initial
calibration is also required ! There isn't any temperature sensor which
you have only to drop into the circuit and shows you the real temperature
with 0.1 C resolution.
If precision of 1C is enough than DS1820.

Vasile

On Tue, 15 Jan 2002, Rick Mann wrote:

> My application requires a remote temperature sensor, accurate to a degree F
> or better. I need to be able to place a temp probe 2 to 3 meters away from
> the controller.
>
> I was thinking of using an LM34DZ with a three-wire cable (and sealing up
> the sensor in some heat shrink), then I saw a post about the LM335, (which
> reads degrees K), and I decided that made more sense (it avoids the need for
> a negative Vref).
>
> However, the LM335 is a two-terminal device (plus the adjust), and requires
> a current source. The app note shows a generalized current source (can I
> just use a resistor?). And the trimmer pot looks like it should be near the
> sensor; is that necessary? Or can it be on the board?
>
> If anyone has any other suggestions for a variable-voltage-output sensor to
> operate in the room temperature range, I'd appreciate it. Thanks!
>
> --Rick
>
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