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					Humidity Sensor

     Presented by:
     Key Kai Wong
                     Outline
•   What is Relative Humidity
•   Manufacturers of Humidity Sensor
•   Humidity Sensor from Honeywell ( HIH series)
•   Humidity Sensor from Sensirion ( SHT Series)
•   Comparision..
•   Conclusion
•   Reference
     What is Relative Humidity (RH)

  Measurement - Relative humidity (RH) is the amount
  of water vapor in the air compared with the amount of
  vapor needed to make the air saturated at the air's
  current temperature


Example:
  At 3 p.m. the air has 9 grams of water vapor per cubic
  meter of air. We divide 9 by 30 and multiply by 100 to get
  a relative humidity of 30%
Water vapor air can hold in degrees C

30 degrees     30 grams per cubic meter of air
20 degrees     17 grams per cubic meter of air
10 degrees      9 grams per cubic meter of air


.
Manufacturers of Humidity Sensor

Honeywell              Sensirion
( HIH series )        ( SHT Series )
         Humidity Sensor from Honeywell
                   ( HIH series)
• Packages are chemically resistant
• operate in ranges of -40 °C to 85 °C ( -
  40 °F to 185 °F)
• Response time -15 sec in slowly moving
  air at 25 °C
• Low power design – 200 microA @ 5
  Vdc
• Operating volatge 4 – 5.8 v
• On-chip signal processing ensures
  linear voltage output versus %RH.
• $35 - $40 per unit price
HIH-3610 Series
          Humidity Sensor from Sensirion
                  ( SHT Series )

• 2 sensors for relative humidity & temperature
• Very easy-to-use due to calibration & digital 2-
  wire interface
• Calibrated & digital output (2-wire interface)
• Fast response time < 4 sec.
• Temp. accuracy: +/- 0.5°C @ 25 °C
• Low power consumption (typ. 30 µW)
• Operating Voltage 2.8 - 5.5v
• Cost $18 - $24 per unit price
Series interface
                          Comparision..
                 Honeywell                             Sensirion
               ( HIH series )                         ( SHT Series )
•   Response time -15 sec in slowly     •   Fast response time < 4 sec.
    moving air at 25 °C
•   Low power design – 200 microA @ 5   •   Low power consumption (typ. 30
    Vdc                                     µW)
•   Operating volatge 4 – 5.8 v         •   Operating Voltage 2.8 - 5.5v
•   $35 - $40 per unit price            •   Cost $18 - $24 per unit price
•   On-chip signal processing ensures   •   2 sensors for relative humidity &
    linear voltage output versus %RH.       temperature
                                        •   Very easy-to-use due to calibration
                                            & digital 2-wire interface
                                        •   Calibrated & digital output (2-wire
                                            interface)
                                        •   Temp. accuracy: +/- 0.5°C @ 25 °C
               Conclusion

 After considering the aspect of the operating
voltage, cost, response time and the output of
the sensor. Sensor SHT series is more suitable
for our application.
                            References

• Honeywell
  http://content.honeywell.com/sensing/prodinfo/humiditymoisture/#applications

• Sensirion
  http://www.sensirion.com/en/sensors/humidity/default.htm

• USToday
  http://www.usatoday.com/weather/wrelhum.htm

				
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posted:4/9/2012
language:English
pages:15