Datasheet

ASAIR
®
4
/
8
Pin
Color
Name
Descripition
1
Red
VDD
Power (3.3V-5.5V)
2
Yellow
SDA
Serial data,two-way port
3
Black
GND
Ground
4
NC
No Connection
5.1 typical circuitOne-wire bus
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AM2311A Technical Manual
Many materials absorb moisture and act as buffer,
which will increase response time and hysteresis.
Therefore, the material around the sensor should be
carefully selected. Recommended materials are:
metal materials, LCP, POM (Delrin), PTFE (Teflon),
PE, PEEK, PP, PB, PPS, PSU, PVDF, and PVF.
Material for sealing and bonding (conservative
recommendation): It is recommended to use method
of filling epoxy resin or silicone resin for packaging
electronic components. Gases released from these
materials may also contaminate AM2311A (see 2.1).
Therefore, the sensor should be finally assembled and
placed in a well-ventilated place, or dried for 24 hours
in an environment of > 50℃ , in order to release the
contaminated gas before packaging.
2.4 Material used for sealing and encapsulation
3 Interface definition
Table 4 Interface definition description
The power supply range of AM2311A is 3.3-5.5V,5.0V
is suggested.
3.1 Power pin(VDD GND)
3.2 Serial data(SDA)
The SDA pin is a three-state structure for reading and
writing sensor data.For the specific communication
sequence, see the detailed description of the
communication protocol.
4 Electric specification
4.1 Absolute maximum rating
The electric specifications of AM2311A are defined in
Table 2. The absolute maximum ratings given in Table
5 are only stress ratings and to provide more
information. Under such conditions, it is not advisable
for the device to perform functional operation.
Exposure to absolute maximum rating for a long time
may affect the reliability of the sensor.
Parameters
Min
Max
Unit
-0.3 5.5 V
-0.3 VDD + 0.3 V
Input current for each pin
-10 10 mA
Table 5 Absolute maximum electric rating
Digital I/O pin
(SDA, SCL) to GND
VDD to GND
ESD electrostatic discharge conforms to JEDEC
JESD22-A114 standard (human body mode ±4kV) and
JEDEC JESD22-A115 (machine mode±200V). If the
test condition exceeds the nominal limit, the sensor
needs additional protection circuit.
4.2 Input/output characteristics
Electric specifications include power consumption, high
and low voltage of input and output, voltage of power
supply. In order to make the sensor communication
smooth, it is important to ensure that the signal design
is strictly limited to the range given in Tables 2 and
Figure 9.
A M 2 31 1 A
5 One-wire bus communication
The typical application circuit connecting the
microprocessor and AM2311A is shown in figure 6.In
one-wire bus communication mode, the SDA pull-up is
connected to the microprocessor's I/O port.
Special specification for one-wire bus
communication：
1.In a typical application circuit, it is recommended to
use 5.1k pull-up resistance when the length of the
connection wire is shorter than 30m, and lower the
resistance value of the pull-up resistance according to
the actual situation when it is larger than 30m.
2.When using 3.3V voltage supply, the length of
connection wire shall not be greater than 1m. Otherwise,
the line pressure drop will cause insufficient sensor
power supply, resulting in measurement errors.
3.Read the sensor minimum every 2 seconds, If the
reading interval is less than 2 seconds, may lead to
temperature or humidity is not allowed or communication
is not successful.When the sensor is powered on at the
beginning, it should wait for more than 2s before reading
the sensor to avoid the unstable state of the sensor.
4.The temperature and humidity value read out each time
is the result of the last measurement. In order to obtain
real-time data, it is necessary to read the sensor twice
continuously. It is recommended to read the sensor
several times continuously, and the accurate data can be
obtained when the sensor interval is more than 2 seconds.
Figure 6 AM2311A One-wire bus application circuitry