Datasheet

www.aosong.com
DHT20 Data Sheet
Version:V1.0 —— May 2021
7 / 13
5 Interface Definition
Pins
Name
Describe
1 2 3 4
1
VDD
Power supply(2.2v to 5.5v)
2
SDA
Serial Data Bidirectional port
3
GND
Ground
4
SCL
Serial clock Bidirectional port
Table 5. ATH21B pin distribution (top view)
5.1 Power Pin(VDD,GND)
The power supply range of DHT20 is 2.2-5.5V.
5.2 Serial Clock SCL
The serial clock is used to synchronize the communication between the microprocessor and DHT20. Since the
interface contains completely static logic, there is no minimum SCL frequency.
5.3 Serial Data SDA
The SDA pin is used for data input and output of the sensor. When sending a command to the sensor, SDA is valid
on the rising edge of the serial clock (SCL), and when SCL is high, SDA must remain stable. After the falling edge
of SCL, the SDA value can be changed. To ensure communication safety, the effective time of SDA should be
extended by T
SU
and T
HO
before the rising edge and after the falling edge of SCL refer to Figure 9. When reading
data from the sensor, SDA is valid (TV) after SCL goes low, and is maintained until the next falling edge of SCL.
Figure 8. Typical application circuit
Note:
1. The power supply voltage of the host MCU must be consistent with the sensor when the product is used in the circuit.
2. If you need to further improve the reliability of the system, you can control the sensor power supply.
3. When the sensor is just powered on, give priority to the sensor VDD power supply, SCL and SDA high level can be set after
5ms.
To avoid signal conflicts, the microprocessor (MCU) must only drive SDA and SCL at low level. An external pull-up
resistor (for example: 4.7kΩ) is required to pull the signal to a high level. The pull-up resistor has been included in
the I/O circuit of the DHT20 microprocessor. Refer to Table 7 and Table 8 for detailed information about sensor
input/output characteristics.