HTU20D Datasheet, PDF (13/23 Pages) TE Connectivity Ltd – Instantaneous desaturation after long periods in saturation phase

HTU20D(F) RH/T SENSOR IC
Digital Relative Humidity sensor with Temperature output
12345678
9 10 11 12 13 14 15 16 17 18
S 1 0 0 0 0 0 0 0 ACK 1 1 1 1 0 1 0 1 ACK
I²C address + write
Command (see table p.9)
19 20 21 22 23 24 25 26 27
Measurement
S
1 0 0 0 0 0 0 1 NACK
measuring
I²C address + read
19 20 21 22 23 24 25 26 27
Measurement
S
1 0 0 0 0 0 0 1 ACK
continue measuring
I²C address + read
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
No Hold Master communication sequence
Grey blocks are controlled by HTU20D(F) sensor.
For Hold Master sequence, bit 45 may be changed to NACK followed by a stop condition to omit checksum
transmission.
For No Hold Master sequence, if measurement is not completed upon “read” command, sensor does not provide
ACK on bit 27 (more of these iterations are possible). If bit 45 is changed to NACK followed by stop condition,
checksum transmission is omitted.
In those examples, the HTU20D(F) sensor output is SRH = ‘0111’1100’1000’0000 (0x7C80). For the calculation of
physical values status bits must be set to ‘0’. Refer to “Conversion of signal outputs” section p.16.
The maximum duration for measurement depends on the type of measurement and resolution chosen. Maximum
values shall be chosen for the communication planning of the MCU. Refer to the table p.4 and p.6 regarding
measuring time specifications.
I²C communication allows for repeated start conditions without closing prior sequence with stop condition.
 Soft reset
This command is used for rebooting the HTU20D(F) sensor switching the power off and on again. Upon reception
of this command, the HTU20D(F) sensor system reinitializes and starts operation according to the default settings
with the exception of the heater bit in the user register. The soft reset takes less than 15ms.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
S 1 0 0 0 0 0 0 0 ACK 1 1 1 1 1 1 1 0 ACK P
I²C address + write
Soft Reset Command
Grey blocks are controlled by HTU20D(F) sensor.
SENSOR SOLUTIONS /// HPC202_5 HTU20D(F) Sensor Datasheet
9/2015
Page 13