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2

Sensor Specifications

Every SHT4x is individually tested and calibrated and is identifiable by its unique serial number (see

section 4.7 for details on the serial number). For the calibration, Sensirion uses transfer standards, which are

subject to a scheduled calibration procedure. The calibration of the reference, used for the calibration of the

transfer standards, is NIST traceable through an ISO/IEC 17025 accredited laboratory.

2.1 Relative Humidity

Parameter

Conditions

Value

Units

SHT40 RH accuracy2

typ.

1.8

%RH

max.

See Figure 2

-

SHT41 RH accuracy2

typ.

1.8

%RH

max.

See Figure 3

-

SHT43 RH accuracy2

typ.

1.8

%RH

max.

See Figure 4

SHT45 RH accuracy2

typ.

1.0

%RH

max.

See Figure 5

-

long-term

production3

0.5

%RH

Repeatability4, 5

high

0.08

%RH

medium

0.15

%RH

low

0.25

%RH

Resolution6

-

0.01

%RH

Hysteresis

At 25 °C

0.8

%RH

Specified range7

extended8

0 to 100

%RH

Response time9

������63%

4

s

Long-term drift10

typ.

<0.2

%RH/y

Table 1. General relative humidity sensor specifications.

2

For definition of typ. and max. accuracy, please refer to the document “Specification Statement and testing humidity sensors”.

3

Maximum value of mean ± 1σ accuracy (data from one year of production) measured at 25°C.

4

The stated repeatability is three times the standard deviation (3σ) of multiple consecutive measurement values at constant conditions

and is a measure for the noise on the physical sensor output. Different repeatability commands are listed in Table 8

5

Valid for 25 °C and 50 %RH.

6

Resolution of A/D converter.

7

Specified range refers to the range for which the humidity or temperature sensor specification is guaranteed.

8

For details about recommended humidity and temperature operating range, please refer to section 2.3.

9

Time for achieving 63% of a humidity step function, measured at 25 °C and 1 m/s airflow. Humidity response time in the application

depends on the design-in of the sensor.

10

Typical value for operation in normal RH/T operating range. Value may be higher in environments with vaporized solvents, out-

gassing tapes, adhesives, packaging materials, etc. For more details please refer to Handling Instructions SHT.