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Telos
Rev B (Low Power Wireless Sensor Module)
Moteiv Corporation Telos (Rev B) : PRELIMINARY Datasheet (12/5/2004) Page 21 of 28
Sensors
Humidity/Temperature Sensor
The optional humidity/temperature sensor is manufactured by Sensirion AG. The SHT11 and
SHT15 models may be directly mounted on the Telos module in the
U3
component position.
The SHT11/SHT15 sensors are calibrated and produce a digital output. The calibration
coefficients are stored in the sensor’s onboard EEPROM. The difference between the SHT11
and SHT15 model is that the SHT15 produces higher accuracy readings as shown in Figure 20.
The sensor is produced using a CMOS process and is coupled with a 14-bit A/D converter. The
low power relative humidity sensor is small in size and may be used for a variety of
environmental monitoring applications.
More information can be found in the SHT1x datasheet available at http://www.sensirion.com
Parameter MIN TYP MAX Units
Humidity
Resolution 0.5 0.03 0.03 %RH
8 12 12 Bit
Repeatability ±0.1 %RH
Range 0 100 %RH
Temperature
Resolution 0.04 0.01 0.01
o
C
0.07 0.02 0.02
o
F
12 14 14 bit
Repeatability ±0.1
o
C
±0.2
o
F
Range -40 123.8
o
C
-40 254.9
o
F
Figure 19 : Sensirion relative humidity and temperature performance specifications
%RH
Relative Humidity absolute accuracy
± 0
± 1
± 2
± 3
± 4
± 5
0 30 40 20 10 80 50 100 70 90 60
%RH
SHT15
SHT11
Temperature accuracy
0 °C
±1 °C
±2 °C
-40°C 0°C 40°C 80°C 120°C
±3 °C
0 °F
±1.8 °F
±3.6 °F
±5.4 °F
-40°F 32°F 104°F 176°F 248°F
SHT11
SHT15
Figure 20 : Accuracy of Sensirion relative humidity and temperature sensors (courtesy Sensirion)