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Version:V1.0 —— May 2021

AHT20 Data Sheet

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Figure 14. The sensor is isolated from the internal heat source to

minimize the effect of internal heat on sensor.

5) The sensor power supply can be controlled

In order to improve the stability of the system, the following power supply controllable scheme is provided:

Figure 15. Typical application circuit.

Note: 1. The power supply voltage range of the host MCU to the sensor is 2.2~5.5V.

2. When the sensor is just powered on, MCU gives priority to VDD power supply, and SCL and SDA high

levels can be set after 5ms.

3. The VDD of the sensor shall be supplemented with RC filtering circuit, as shown in the figure R1 and C1.

6) The wiring rules of the sensor on the PCB

In order to improve the reliability of the sensor, the layout of the circuit board should be avoided in the bottom of

the sensor wiring or copper design.

4.6 Materials for Sealing and Encapsulation

Many materials absorb moisture and will act as a buffer, which will increase response time and lag. Therefore, the

materials around the sensor should be carefully selected. The recommended materials are: metal materials, LCP,

POM(Delrin), PTFE(Teflon), PE, PEEK, PP, PB, PPS, PSU, PVDF, PVF.

Material used for sealing and bonding (conservative recommendation): It is recommended to use epoxy resin to

encapsulate electronic components, or silicone resin. The gases released by these materials may also contaminate

AHT20 (see 4.2). Therefore, the sensor should be assembled last, and placed in a well-ventilated place, or dried for

24 hours in an environment of >50℃, so as to release the polluted gas before packaging.

4.7 Wiring Rules and Signal Integrity

If the SCL and SDA signal lines are parallel and very close to each other, it may cause signal crosstalk and

communication failure. The solution is to place VDD and/or GND between the two signal lines, separate the signal

lines, and use shielded cables. In addition, reduce

SCL frequency may also improve the integrity of signal transmission. A 10uF decoupling capacitor must be added

between the power supply pins (VDD, GND) for filtering. This capacitor should be as close as possible to the sensor.

See the next chapter.