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PDF HTU21DF Data sheet ( Hoja de datos )
| Número de pieza | HTU21DF | |
| Descripción | Digital Relative Humidity sensor | |
| Fabricantes | Measurement | |
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HTU21D(F) Sensor
Digital Relative Humidity sensor with Temperature output
DFN type package
Relative Humidity and Temperature Digital Output, I²C
interface
Fully calibrated
Lead free sensor, reflow solderable
Low power consumption
Fast response time
DESCRIPTION
The HTU21D(F) is a new digital humidity sensor with temperature output by MEAS. Setting new standards in
terms of size and intelligence, it is embedded in a reflow solderable Dual Flat No leads (DFN) package with a
small 3 x 3 x 0.9 mm footprint. This sensor provides calibrated, linearized signals in digital, I²C format.
HTU21D(F) digital humidity sensors are dedicated humidity and temperature plug and play transducers for OEM
applications where reliable and accurate measurements are needed. Direct interface with a micro-controller is
made possible with the module for humidity and temperature digital outputs. These low power sensors are
designed for high volume and cost sensitive applications with tight space constraints.
Every sensor is individually calibrated and tested. Lot identification is printed on the sensor and an electronic
identification code is stored on the chip – which can be read out by command. Low battery can be detected and
a checksum improves communication reliability. The resolution of these digital humidity sensors can be changed
by command (8/12bit up to 12/14bit for RH/T).
With MEAS’ improvements and miniaturization of this sensor, the performance-to-price ratio has been improved
– and eventually, any device should benefit from its cutting edge energy saving operation mode.
Optional PTFE filter/membrane (F) protects HTU21D digital humidity sensors against dust and water immersion,
as well as against contamination by particles. PTFE filter/membranes preserve a high response time. The white
PTFE filter/membrane is directly stuck on the sensor housing.
FEATURES
APPLICATIONS
Full interchangeability with no calibration required Automotive: defogging, HVAC
in standard conditions
Home Appliance
Instantaneous desaturation after long periods in
Medical
saturation phase
Printers
Compatible with automatized assembly processes, Humidifier
including Pb free and reflow processes
Individual marking for compliance to stringent
traceability requirements
HPC199_3 HTU21D(F) Sensor Datasheet
www.meas-spec.com
1/21
October 2013
Free Datasheet http://www.datasheet-pdf.com/
1 page  
HTU21D(F) Sensor
Digital Relative Humidity sensor with Temperature output
TEMPERATURE
Characteristics
Symbol
Min Typ
Max Unit
Resolution
14 bit
12 bit
0.01 °C
0.04 °C
Temperature Operating Range
T -40
+125
°C
Temperature Accuracy @25°C
typ
max
±0.3
See graph 2
°C
°C
Replacement
fully interchangeable
14 bit
44 50 ms
Measuring time (1)
13 bit
12 bit
22 25 ms
11 13 ms
11 bit
6 7 ms
PSSR
±25 LSB
Long term drift
0.04 °C/yr
Response Time (at 63% of signal) from 15°C to 45°C (2)
τT
10 s
(1) Typical values are recommended for calculating energy consumption while maximum values shall be applied for
calculating waiting times in communication.
(2) At 1m/s air flow
GRAPH 2 : TEMPERATURE ERROR BUDGET
2
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
-40 -20 0
Maximal Tolerance
Typical Tolerance
20 40 60
Temperature (°C)
80
100 120
USER GUIDE HTU21D(F)
APPLICATION INFORMATION
Soldering instructions: Lead free reflow soldering recommended process
For soldering HTU21D(F) sensor standard reflow soldering ovens may be used.
HPC199_3 HTU21D(F) Sensor Datasheet
www.meas-spec.com
5/21
October 2013
Free Datasheet http://www.datasheet-pdf.com/
5 Page 
HTU21D(F) Sensor
Digital Relative Humidity sensor with Temperature output
Command
Trigger Temperature Measurement
Trigger Humidity Measurement
Trigger Temperature Measurement
Trigger Humidity Measurement
Write user register
Read user register
Soft Reset
Code
0xE3
0xE5
0xF3
0xF5
0xE6
0xE7
0xFE
Comment
Hold master
Hold master
No Hold master
No Hold master
Hold/No Hold master modes
There are two different operation modes to communicate with the HTU21D(F) sensor: Hold Master mode and
No Hold Master mode.
In the first case, the SCK line is blocked (controlled by HTU21D(F) sensor) during measurement process while
in the second case the SCK line remain open for other communication while the sensor is processing the
measurement.
No Hold Master mode allows for processing other I²C communication tasks on a bus while the HTU21D(F)
sensor is measuring. A communication sequence of the two modes is available below.
In the Hold Master mode, the HTU21D(F) pulls down the SCK line while measuring to force the master into a
wait state. By releasing the SCK line, the HTU21D(F) sensor indicates that internal processing is completed and
that transmission may be continued.
In the No Hold Master mode, the MCU has to poll for the termination of the internal processing of the
HTU21D(F) sensor. This is done by sending a start condition followed by the I²C header (‘1’ for Read access:
0x81) as shown below. If the internal processing is finished, the HTU21D(F) sensor acknowledges the poll of the
MCU and data can be read by the MCU. If the measurement processing is not finished, the HTU21D(F) sensor
answers no ACK bit and start condition must be issued once more.
For both modes, since the maximum resolution of the measurement is 14 bits, the two last least significant bits
(LSBs, bits 43 and 44) are used for transmitting status information. Bit 1 of the two LSBs indicates the
measurement type (‘0’: temperature, ‘1’: humidity). Bit 0 is currently not assigned.
12345678
9 10 11 12 13 14 15 16 17 18
S 1 0 0 0 0 0 0 0 ACK 1 1 1 0 0 1 0 1 ACK
I²C address + write
Command (see table p.9)
19 20 21 22 23 24 25 26 27
S 1 0 0 0 0 0 0 1 ACK
Measurement
I²C address + read
Hold during measurement
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
0 1 1 1 1 1 0 0 ACK 1 0 0 0 0 0 1 0 ACK
Data (MSB)
Data (LSB)
Status
46 47 48 49 50 51 52 53 54
1 0 0 1 0 1 1 1 NACK P
Checksum
Hold Master communication sequence
HPC199_3 HTU21D(F) Sensor Datasheet
www.meas-spec.com
11/21
October 2013
Free Datasheet http://www.datasheet-pdf.com/
11 Page | ||
| Páginas | Total 21 Páginas | |
| PDF Descargar | [ Datasheet HTU21DF.PDF ] | |
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