SHT15 SENSIRION, SHT15 Datasheet - Page 6

Humidity Sensor

SHT15

Manufacturer Part Number
SHT15
Description
Humidity Sensor
Manufacturer
SENSIRION
Datasheet

Specifications of SHT15

Sensing Accuracy
2%
Sensor Output
Digital
Sensor Terminals
SMD
Humidity Accuracy ±
2%
Peak Reflow Compatible (260 C)
Yes
Terminal Type
PCB Surface Mount
Humidity Range
0 To 100% RH
Response Time
8s
Leaded Process Compatible
Yes
Package / Case
4-LCC SMD
Rohs Compliant
Yes
Lead Free Status / RoHS Status
Lead free / RoHS Compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
SHT15
Manufacturer:
SENSIRION
Quantity:
1 200
Part Number:
SHT15
Manufacturer:
SENSIRION
Quantity:
20 000
Datasheet SHT1x
Absolute maximum ratings for VDD versus GND are +7V
and -0.3V. Exposure to absolute maximum rating
conditions for extended periods may affect the sensor
reliability (e.g. hot carrier degradation, oxide breakdown).
For proper communication with the sensor it is essential to
make sure that signal design is strictly within the limits
given in Table 3 and Figure 11.
Figure 11: Timing Diagram, abbreviations are explained in
Table 3. Bold DATA line is controlled by the sensor, plain DATA
line is controlled by the micro-controller. Note that DATA valid
read time is triggered by falling edge of anterior toggle.
Table 3: SHT1x I/O signal characteristics, OL stands for Output
Load, entities are displayed in Figure 11.
3 Communication with Sensor
3.1
As a first step the sensor is powered up to chosen supply
voltage VDD. The slew rate during power up shall not fall
below 1V/ms. After power-up the sensor needs 11ms to
get to Sleep State. No commands must be sent before
that time.
www.sensirion.com
F
T
T
T
T
T
T
T
*
**
***
****
SCK
SCKx
R
FO
RO
V
SU
HO
SCK
DATA
/T
T
F
SU
Parameter
SCK Frequency
SCK hi/low time
SCK rise/fall time
DATA fall time
DATA rise time
DATA valid time
DATA setup time
DATA hold time
T
T
T
line capacitance (Cbus) at DATA line
T
Start up Sensor
R_max
R0
V_max
H0_max
is determined by the R
and T
+ T
< T
DATA valid write
F_max
V
SU_max
– max (T
T
= (F
SCKH
depend on external pull-up resistor (R
SCK
R0
)
-1
T
, T
Conditions
VDD > 4.5V
VDD < 4.5V
OL = 5pF
OL = 100pF 30
SCK
– T
F0
P
SCKH
)
*C
T
SCKL
bus
– T
T
DATA valid read
HO
time-constant at DATA line
T
SCKL
V
T
R
min typ max Units
100
200 250
100 150
3.5
10
**
0
0
1
200
0.1
0.1
10
40
15
**
T
F
P
) and total bus
200
****
20
***
***
**
5
1
*
Version 4.3 – May 2010
MHz
MHz
T
ns
ns
ns
ns
ns
ns
ns
ns
RO
20%
80%
20%
T
80%
FO
3.2
To initiate a transmission, a Transmission Start sequence
has to be issued. It consists of a lowering of the DATA line
while SCK is high, followed by a low pulse on SCK and
raising DATA again while SCK is still high – see Figure 12.
Figure 12: "Transmission Start" sequence
The subsequent command consists of three address bits
(only ‘000’ is supported) and five command bits. The
SHT1x indicates the proper reception of a command by
pulling the DATA pin low (ACK bit) after the falling edge of
the 8th SCK clock. The DATA line is released (and goes
high) after the falling edge of the 9th SCK clock.
Command
Reserved
Measure Temperature
Measure Relative Humidity
Read Status Register
Write Status Register
Reserved
Soft reset, resets the interface, clears the
status register to default values. Wait minimum
11 ms before next command
Table 4: SHT1x list of commands
3.3
After issuing a measurement command (‘00000101’ for
relative humidity, ‘00000011’ for temperature) the
controller has to wait for the measurement to complete.
This takes a maximum of 20/80/320 ms for a 8/12/14bit
measurement. The time varies with the speed of the
internal oscillator and can be lower by up to 30%. To
signal the completion of a measurement, the SHT1x pulls
data line low and enters Idle Mode. The controller must
wait for this Data Ready signal before restarting SCK to
readout the data. Measurement data is stored until
readout, therefore the controller can continue with other
tasks and readout at its convenience.
Two bytes of measurement data and one byte of CRC
checksum (optional) will then be transmitted. The micro
controller must acknowledge each byte by pulling the
DATA line low. All values are MSB first, right justified (e.g.
the 5
first byte is not used).
SCK
DATA
th
Sending a Command
Measurement of RH and T
SCK is MSB for a 12bit value, for a 8bit result the
Code
0000x
00011
00101
00111
00110
0101x-1110x
11110
6/11
80%
20%
20%
80%

Related parts for SHT15