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Product Summary
AHT21B is equipped with a newly designed ASIC dedicated chip, an improved MEMS semiconductor capacitive
humidity sensor component and a standard on-chip temperature sensor component. Its performance has been
greatly improved and even beyond the reliability level of the previous generation of sensor, which make it more
stable in the harsh conditions. Each sensor had been rigorously calibrated and tested. Due to the improvement
and miniaturization of the sensors, it is more cost-effective.
Data Sheet AHT21B
Humidity and Temperature Module
• Relative humidity and temperature output
• Superior sensor performance, typical accuracy RH: ±3%, T: ±0.5℃
• Fully calibrated and processed digital output, I²C protocol
• Wide voltage support 2.2 to 5.5V DC
• Excellent long-term stability
• Fast-response and anti-interference capability
1 Product Description
The AHT21B is a kind of sensor of humidity and temperature with digital I²C output. It can be
applied to HVAC, dehumidifier, testing and inspection equipment, consumer products,
automobiles, automatic control, data loggers, weather stations, home appliances, humidity control,
medical and other application fields which need to detect and control temperature and humidity.
Figure 1. ATH21B
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Version:V1.0 —— May 2021
ATH21B Data Sheet
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2 Sensor Specifications
Relative Humidity
Parameter
Condition
Min
Typical
Value
Max
Unit
Resolution
Typical
-
0.024
-
%RH
Accuracy
Typical
-
±3
-
%RH
Tolerance
1
Max
See Figure 2
-
%RH
Repeatable
-
-
±0.1
-
%RH
Hysteresis
-
-
±1
-
%RH
Nonlinear
-
-
<0.1
-
%RH
Response Time
2
63%
-
<8
-
s
Scope of Work
Extended
3
0
-
100
%RH
Prolonged Drift
4
Normal
-
<1
-
%RH/yr
Table 1. Humidity characteristics table
Figure 2. Typical and maximum humidity errors
Electrical Specifications
Parameter
Condition
Min
Typical Value
Max
Unit
Supply Voltage
Typical
2.2
3.3
5.5
V
Supply Current,
IDD
5
Dormancy
-
250
-
nA
Measure
-
980
-
µA
Power
Consumption
6
Dormancy
-
-
0.8
µW
Measure
-
3.2
-
mW
Communication
Standard I²C protocol
Table 2. Electrical Specifications