SHT71 datasheet(5/9 Pages) ETC

5 / 9 page

SHT1x / SHT7x Relative Humidity & Temperature Sensor System

www.sensirion.com

v2.02 July 2004

5/9

3 Converting Output to Physical Values

3.1 Relative Humidity

To compensate for the non-linearity of the humidity sensor

and to obtain the full accuracy it is recommended to convert

the readout with the following formula1:

linear

•

SORH

12 bit

-4

0.0405

-2.8 * 10-6

8 bit

-4

0.648

-7.2 * 10-4

Table 6

Humidity conversion coefficients

For simplified, less computation intense conversion formulas

see application note “RH and Temperature Non-Linearity

Compensation”.

The humidity sensor has no significant voltage dependency.

SORH sensor readout (12bit)

Figure 10 Conversion from SORH to relative humidity

3.1.1 Humidity Sensor RH/Temperature compensation

For temperatures significantly different from 25 °C (~77 °F)

the temperature coefficient of the RH sensor should be

considered:

linear

true

)

25)

•

= °

SORH

12 bit

0.01

0.00008

8 bit

0.01

0.00128

Table 7

Temperature compensation coefficients

This equals ~0.12 %RH / °C @ 50 %RH

1 Where SORH is the sensor output for relative humidity

3.2 Temperature

The bandgap PTAT (Proportional To Absolute Temperature)

temperature sensor is very linear by design. Use the

following formula to convert from digital readout to

temperature:

Temperatur

•

VDD

d1 [°C]

d1 [°F]

SOT

d2 [°C] d2 [°F]

-40.00

14bit

0.01

0.018

-39.75

-39.50

12bit

0.04

0.072

3.5V

-39.66

-39.35

-39.60

-39.28

2.5V

-39.55

-39.23

Table 8

Temperature conversion coefficients

For improved accuracies in extreme temperatures with more

computation intense conversion formulas see application

note “RH and Temperature Non-Linearity Compensation”.

3.3 Dewpoint

Since humidity and temperature are both measured on the

same monolithic chip, the SHTxx allows superb dewpoint

measurements. See application note “Dewpoint calculation”

for more.

SHT71 bảng dữ liệu(PDF) 5 Page - List of Unclassifed Manufacturers

SHT71 bảng dữ liệu(HTML) 5 Page - List of Unclassifed Manufacturers

Html Pages

1 2 3 4 5 6 7 8 9

bảng dữ liệu tải về

Link URL