Anyone used the DS1629 in high resolution mode?

[Acetronics2]

I am having troubles with the DS1629 combined RTC and temperature sensor. The DS1629 consistently reads about 1.5 C higher than the temperature sensor in an Intersema pressure/temperature sensor. Same results for 20 systems, both devices on same PCB.

Hi, Brian

Real-time clock/calendar
±2°C thermometer accuracy from -10°C to +85°C
Measures temperatures from -55°C to +125°C (-67°F to +257°F)
9-bit (expandable) temperature resolution
...

Dallas claims +/- 2°C ACCURACY ...

with your 1.5°C difference ... you're into the specs !!!

If my memory is right Intersema claims +/- .7 °C Accuracy ...

NOW ...

if you look for the 1/10 degree ...

- take care to incident light on the sensor ... .4°C observed with a DS18B20
- take care to every component dissipating a bit in the surroundings ( IR illumination ! + PCB conduction ) especially regulators ...
- take care to self-heating, as Bill raises ...

Now ... without any serious individual calibration ... ( 3 points as a minimum ! ) ...

DO NOT hope to be considered " serious " if claiming a .1°C resolution with a +/- 2°C ACCURACY sensor ...


Alain