StephenL Posted November 11, 2009 Report Share Posted November 11, 2009 I am looking for temperature sensor with +/- 0.5 degree accuracy at 25 degrees. The DS18B20 would do the job well, but does not work over the range of 1.8V to 3.6V. Other type such as the DS75LV, and LM94022 are not accurate enough. Digital output is preferred, but can work with analogue output. The sensor is to be built into a probe with a 2 meter connecting lead.Thank you for any suggestions. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted November 11, 2009 Report Share Posted November 11, 2009 The low voltage of 1.8V is going to be the problem.What about using a precision thermistor? Quote Link to comment Share on other sites More sharing options...
StephenL Posted November 12, 2009 Author Report Share Posted November 12, 2009 A thermistor is a good idea. The uP I am using is the SiLabs C8051F930. The A/D full scale is 1.68V. This would require an amplifier or else the self heating of the thermistor would be high. Also I would need a precision current source.This job is quite price sensitive. Just hoping for the equivalent of a DS18B20 that runs at 1.8V. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted November 12, 2009 Report Share Posted November 12, 2009 You don't need a current source: use the power supply as the A/D reference and connect the the thermistor as part of a potential divider. Self heating won't be much of a problem as long as you keep the power dissipation low.I doubt you'll find an IC, high accuracy, low voltage and low cost are not compatible. Quote Link to comment Share on other sites More sharing options...
StephenL Posted November 22, 2009 Author Report Share Posted November 22, 2009 We have gone with the LM94022 which give very low power consumption (6uA). The accuracy is only +/- 1.5 degrees C at 25 degrees so it will need calibration. Thank you for your suggestions and avoidance of a constant current supply. You are right that low voltage ==> higher prices. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted November 22, 2009 Report Share Posted November 22, 2009 Good you came up with a solution.Thanks for returning to tell us about how you did it, most people don't bother. Quote Link to comment Share on other sites More sharing options...
rakeshkoku Posted February 19, 2010 Report Share Posted February 19, 2010 good post keep it up Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.