28018 Parallax Inc, 28018 Datasheet - Page 4

• Manufacturer Part Number: 28018
• Description: MODULE SENSOR TEMP+HUMIDITY
• Manufacturer: Parallax Inc
• Series: Sensirion SHT11r

Specifications of 28018

• Output Type: Digital - 2-Wire
• Sensor Type: Humidity and Temperature
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

SHT1x / SHT7x Relative Humidity & Temperature Sensor System
Figure 6
2.3 Status Register
Some of the advanced functions of the SHTxx are available
through the status register. The following section gives a
brief overview of these features. A more detailed description
is available in the application note “Status Register”
Figure 7
Figure 8
Bit Type
7
6
5
4
3
2
1
0
Table 3
2.3.1
The default measurement resolution of 14bit (temperature)
and 12bit (humidity) can be reduced to 12 and 8 bit. This is
especially useful in high speed or extreme low power
applications.
2.3.2
The “End of Battery” function detects VDD voltages below
2.47V. Accuracy is ±0.05V
2.3.3
An on chip heating element can be switched on. It will
increase the temperature of the sensor by approximately 5°C
(9°F). Power consumption will increase by ~8mA @ 5V.
Applications:
By comparing temperature and humidity values before and
1)
(2)
(3)
www.sensirion.com
0
0
Parameters are periodically sampled and not 100% tested
With one measurement of 8 bit accuracy without OTP reload per second
With one measurement of 12bit accuracy per second
0
R
R/W
R/W
R/W
0
0
0
0
0
0 0
0 0 1 1
Command
Command
Measurement resolution
End of Battery
Heater
0
Description
reserved
End of Battery (low voltage detection)
‘0’ for Vdd > 2.47
‘1’ for Vdd < 2.47
reserved
reserved
For Testing only, do not use
Heater
no reload from OTP
’1’ = 8bit RH / 12bit Temperature resolution
’0’ = 12bit RH / 14bit Temperature resolution
Overview of Measurement Sequence (TS =Transmission Start)
Status Register Write
Status Register Read
Status Register Bits
1 1
Command
0
1
Status
Reg
Status
Reg
wait for data ready
Checksum
0
Default
0
X
0
0
0
0
0
0
No default value,
bit
updated after a
measurement
off
reload
12bit RH
14bit Temp.
MSB
is
v2.0 March 2003
only
after switching on the heater, proper functionality of both
sensors can be verified.
Warning: While heated the SHTxx will show higher
temperatures and a lower relative humidity than with no
heating.
2.4 Electrical Characteristics
VDD=5V, Temperature= 25°C unless otherwise noted
Table 4
Table 5
DATA
Figure 9
• In high (>95%) RH environments heating the sensor
Parameter
Power supply DC
Supply current
Low level output voltage
High level output voltage
Low level input voltage
High level input voltage Positive going
Input current on pads
Output peak current
F
T
T
T
T
T
T
SCK
SCK
RFO
CLx
V
SU
HO
R
/T
element will prevent condensation, improve response
time and accuracy
F
Parameter
SCK frequency
DATA fall time
SCK hi/low time
DATA valid time
DATA set up time
DATA hold time
SCK rise/fall time
SHTxx DC Characteristics
SHTxx I/O Signals Characteristics
Timing Diagram
LSB
T
CLH
T
Conditions
measuring
average
sleep
Negative going
on
Tristated (off)
Conditions
VDD > 4.5 V
VDD < 4.5 V
Output load 5 pF
Output load 100 pF
V
F
T
SCK
SU
(1)
Min. Typ. Max. Units
75%
80%
2.4
2
0
0
(2)
Checksum
T
Min Typ. Max. Unit
100
100
3.5 10
R
30 40 200 ns
T
0
28
HO
550
0.3
10
5
(3)
250
200
10
100% Vdd
100% Vdd
20% Vdd
20% Vdd
5.5 V
1
1
4
10 MHz
20 ns
1 MHz
µA
µA
µA
µA
mA
µA
ns
ns
ns
ns
ns
T
F
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