Würth Elektronik 2525020210001 User Guide [ml]
HUMIDITY SENSOR WITH INTEGRATED
TEMPERATURE SENSOR
WSEN-HIDS
USER MANUAL
2525020210001
VERSION 1.3
DECEMBER 8, 2020
Revision history
Manual
version
1.0 1.0
1.1 1.0
1.2 1.0
1.3 1.0
Product
version
Notes
• Initial release of the manual
• Temperature measurement range is
changed in chapter 2.2
• Slave address of the humidity sensor
changed
• I2C multiple byte read operation
chapter added
• Chapter 7.2: Flow chart updated
• Chapter 9: Sensor output data
updated
Date
September 2020
October 2020
October 2020
December 2020
Humidity sensor with integrated temperature sensor, Part Nr. 2525020210001
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Abbreviations
Abbreviation Description
BDU Block update data
DRDY Data ready
ESD Electrostatic discharge
FIFO First-in first-out
I2C Inter integrated circuit
LGA Land grid array
LSB Least significant bit
MEMS Micro-Electro Mechanical system
MSB Most significant bit
ODR Output data rate
PCB Printed circuit board
SPI Serial peripheral interface
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Contents
1 Product description 6
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Sensor features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.5 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Sensor and electrical specifications 8
2.1 Humidity sensor specifications . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 Temperature sensor specifications . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.4 Absolute maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.5 General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3 Pinning description 11
4 Application circuit 12
5 Digital interface 13
5.1 General characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2 SDA and SCL logic levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3 Communication phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3.1 Idle state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3.2 START(S) and STOP(P) condition . . . . . . . . . . . . . . . . . . . 14
5.3.3 Data validity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3.4 Byte format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.3.5 Acknowledge (ACK) and No-Acknowledge (NAACK) . . . . . . . . 15
5.3.6 Slave address for the sensor . . . . . . . . . . . . . . . . . . . . . . 15
5.3.7 Read/Write operation . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.4 I2C Multiple bytes read operation . . . . . . . . . . . . . . . . . . . . . . . . 17
5.5 I2C timing parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6 Serial Peripheral Interface (SPI) 19
6.1 Data transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.2 Communication modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.3 Sensor SPI Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.3.1 SPI write operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.3.2 SPI read operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.3.3 SPI timing parameters . . . . . . . . . . . . . . . . . . . . . . . . . 23
7 Quick start guide 24
7.1 Communication check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.2 Sensor in operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8 Operating modes 26
8.1 Continuous mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
8.2 One shot mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Humidity sensor with integrated temperature sensor, Part Nr. 2525020210001
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9 Sensor output data 28
9.1 Humidity sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
9.2 Steps to calculate humidity output value . . . . . . . . . . . . . . . . . . . . 28
9.3 Temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9.4 Steps to compute temperature output value . . . . . . . . . . . . . . . . . . 29
10 Sensor register mapping 31
10.1 Calibration Register mapping . . . . . . . . . . . . . . . . . . . . . . . . . . 32
11 Register description 33
11.1 Device_ID (0x0F) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
11.2 Average (0x10) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
11.3 CTRL_1 (0x20) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
11.3.1 Block data update (BDU) . . . . . . . . . . . . . . . . . . . . . . . . 34
11.4 CTRL_2 (0x21) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
11.4.1 BOOT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
11.4.2 Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
11.5 CTRL_3 (0x22) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
11.6 STATUS (0x27) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
11.7 H_OUT_L (0x28) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
11.8 H_OUT_H (0x29) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
11.9 T_OUT_L (0x2A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
11.10 T_OUT_H (0x2B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
12 Handling humidity sensor 39
13 Physical dimensions 40
13.1 Module drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
13.2 Footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
14 Manufacturing information 42
14.1 Moisture sensitivity level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
14.2 Soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
14.2.1 Reflow soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
14.2.2 Cleaning and washing . . . . . . . . . . . . . . . . . . . . . . . . . 44
14.2.3 Potting and coating . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
14.2.4 Storage conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
14.2.5 Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
15 Important notes 46
15.1 General customer responsibility . . . . . . . . . . . . . . . . . . . . . . . . . 46
15.2 Customer responsibility related to specific, in particular safety-relevant ap-
plications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
15.3 Best care and attention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
15.4 Customer support for product specifications . . . . . . . . . . . . . . . . . . 46
15.5 Product improvements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
15.6 Product life cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
15.7 Property rights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
15.8 General terms and conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Humidity sensor with integrated temperature sensor, Part Nr. 2525020210001
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16 Legal notice 48
16.1 Exclusion of liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
16.2 Suitability in customer applications . . . . . . . . . . . . . . . . . . . . . . . 48
16.3 Usage restriction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
17 License terms for Würth Elektronik eiSos GmbH & Co. KG sensor product
software and source code 50
17.1 Limited license . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
17.2 Usage and obligations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
17.3 Ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
17.4 Disclaimer of warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
17.5 Limitation of liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
17.6 Applicable law and jurisdiction . . . . . . . . . . . . . . . . . . . . . . . . . . 51
17.7 Severability clause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
17.8 Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
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1 Product description
0.9 mm
1.1 Introduction
The humidity sensor is a 16-bit digital ultra-low-power and high-performance sensor with
digital output interface. It measures relative humidity from 0 to 100% rH with an output data
rate of 1 Hz, 7 Hz and 12.5 Hz. It is embedded with a temperature sensor for ambient temperature measurement. The sensor is fully calibrated and no further calibration is required.
The dimension of the sensor is 2.0 mm×2.0 mm×0.9 mm. It is available in land grid array
package (LGA).
1.2 Applications
• HVAC systems
• Home and building automation
• Goods and asset tracking
• Air conditioners
• Refrigerators
1.3 Sensor features
• Humidity measurement range :
• Humidity noise :
• Temperature measurement range :
• Temperature noise :
• Output data rate :
• Operating modes :
• Current consumption :
• Communication interface :
0 to 100 % rH
0.35 rH % RMS
-40 to +120 °C
0.03 °C RMS
1 Hz, 7 Hz and 12.5 Hz
Continuous mode and one-shot mode
8.9µA @ODR 1Hz
I2C, SPI and Interrupt pin
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1.4 Block diagram
Multiplexer
ADC
Controller
Logic &
Interrupt
Op
Amp
Timming
Circuits
Voltage &
Current Bias
Digital
Interface
SDA
SCL
Clock
Generator
CS
INT
Humidity capacitor
sensing element
Temperature
Sensor
Figure 1: Block diagram
The sensor is a MEMS based capacitive humidity sensor with an integrated ASIC. MEMS
sensing element is a planar fringed capacitor with a dielectric polymer which absorbs or releases water with proportional to the relative humidity in the environment. A silicon based
temperature sensor is integrated in the same package. ASIC comprises of multiplier, operational amplifier, analog-to-digital converter and other signal conditioning blocks like controller
logics and interrupts. ASIC converts the analog signal from the both humidity and temperature sensing element into a 16-bit digital humidity and temperature values. The sensor is
factory calibrated for both humidity and temperature measurements. The trimming parameters are stored in on-chip flash memory. When the sensor is powered on, these trimming
parameters are loaded from the flash memory to the registers. Hence, no further calibration
is required for humidity and temperature values.
1.5 Ordering information
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WE order code Temperature Range Description
2525020210001 -40° C to +120° C Tape & reel packaging
Table 1: Ordering information
2 Sensor and electrical specifications
T=25°C, supply voltage VDD = 3.3V, unless otherwise stated.
2.1 Humidity sensor specifications
Parameters Symbol Test conditions Min.1Typ. Max.
1
Unit
Measurement range H
Resolution RES
Sensitivity SEN
Accuracy H
RANGE
H
H
ACC
20% rH to 80% rH ±3.5
0 100
16
0.004
0% rH to 100% rH ±5
Noise(RMS) H
Hystersis HYS
Long-term drift H
Response time H
NOISE
H
DRIFT
STEP
Internal average:
32 samples
2
0.35
±1
20% rH to 80% rH 0.5
Step response
time of 63%
10
Output data rate ODR 1 12.5
Table 2: Humidity sensor specification
1
Minimum and maximum values are based on characterization at 3σ.
2
Default setting
% rH
bits
% rH/digit
% rH
% rH
% rH RMS
% rH
% rH/Year
s
Hz
2.2 Temperature sensor specifications
Parameters
Measurement range
Resolution
Noise(RMS)
Sensitivity
Absolute accuracy
Symbol
T
RANGE
RES
T
NOISE
SEN
T
ACC_ABS
Test conditions
T
Internal average:
16 samples
T
2
15°C to 40°C ±0.5
0°C to 60°C ±1
Table 3: Temperature sensor specification
1
Minimum and maximum values are based on characterization at 3σ.
2
Default setting
1
Min.
-40 +120 °C
Typ.
16
0.03
0.016
Max.
1
°C RMS
Unit
bits
°C/digit
°C
°C
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2.3 Electrical specifications
Parameters
Operating supply voltage
Current consumption
Current consumption in
power down mode
Symbol
V
DD
I
DD
I
DD_PD
Test
conditions
ODR 1 Hz 8.9
Min.
1.7
1
Table 4: Electrical specification
1
Minimum and maximum values are based on characterization at 3σ.
2.4 Absolute maximum rating
Parameter
Input voltage VDDpin
Input voltage SDA, SCL &
CS
Symbol
V
DD
Test conditions
VINpins -0.3 V
Min.
-0.3 4.8 V
Typ.
3.3
0.5
1
Max.1Unit
3.6 V
Max.
DD_IO
1
+ 0.3 V
µA
µA
Unit
Table 5: Absolute maximum rating
1
Minimum and maximum values are based on characterization at 3σ.
Supply voltage on any pin should never exceed 4.8 V
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2.5 General information
Parameters Values
Operating temperature -40°C to +120°C
Storage temperature -40°C to +125°C
Communication interface I2C & SPI
Moisture sensitivity level (MSL) 3
Electrostatic discharge protection(HBM) 2 kV
The device is susceptible to damage by electrostatic discharge (ESD). Always
use proper ESD precautions when handling. Improper handling of the device
can cause performance degradation or permanent damage to the part
Table 6: General information
For better performance, the recommended storage condition for the humidity
sensor is 10°C to 40°C with 20% rH to 60% rH
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3 Pinning description
VDD
SCL
INT
SDA
GND
CS
6
5
4
3
2
1
Figure 2: Pinout (top view)
No Function Description Input/Output
1 VDD Positive supply voltage Supply
2 SCL I2C serial clock Input
3 INT Data ready output signal Output
4 SDA I2C / SPI: serial data input/output Input/Output
5 GND Negative supply voltage Supply
6 CS I2C/SPI enable/disable Input
Table 7: Pin description
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4 Application circuit
12
3
4 5
6
SCL
INT
SDA
VDD
100 nF
CS
GND
VDD
SCL
SDA
Rp Rp
VDD
Rp – Pull up resistor
I²C Bus configuration
SPI 3 wire to 4 wire configuration
SDA
MOSI
MISO
Rs
Rs – Series resistor
Figure 3: Electrical connection (top view)
A positive supply voltage is applied to the sensor through VDD pin and negative voltage to
GND. The decoupling capacitor of 100 nF in parallel is highly recommended to prevent the
voltage ripples on the VDD line. It should be placed as close as possible to the VDD pin.
The CS pin shall be connected to VDD_IO in order to enable the I2C communication interface. For SPI communication, the CS pin shall be connected to master side CS pin for active
start and stop SPI communication. The pull up resistors Rpfor I2C communication interface
should be connected parallel between supply voltage VDD and SCL and SDA pins.
Depending on the internal resistance of I2C pins at the master side, the pull up resistors
Rpcan be selected for proper rise and fall time of the digital signals. The 3-pin to 4-pin SPI
configuration can be configured as mentioned in the figure 3.
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5 Digital interface
Microcontroller
(Master)
R
p
R
p
Sensor
(Slave-1)
Sensor
(Slave-2)
+VDD
SCL
(serial clock)
SDA
(serial data)
Pull up resistors
The humidity sensor supports standard I2C (Inter-IC) bus protocol. Further information of
the I2C interface can be found at https://www.nxp.com/docs/en/user-guide/UM10204.pdf .
I2C is a serial 8-bit protocol with two-wire interface, which supports communication between
different ICs. For example, between the microcontroller and other peripheral devices.
5.1 General characteristics
A serial data line (SDA) and a serial clock line (SCL) are required for the communication
between the devices connected via I2C bus. Both SDA and SCL lines are bidirectional. The
output stages of devices connected to the bus must have an open-drain or open-collector.
Hence, the SDA and SCL lines are connected to a positive supply voltage via pull-up resistors. In I2C protocol, the communication is realized through master-slave principle. The
master device generates the clock pulse, a start command and a stop command for the data
transfer. Each connected device on the bus is addressable via a unique address. Master
and slave can act as a transmitter or a receiver depending upon whether the data needs to
be transmitted or received.
The sensor behaves like a slave device on the I2C bus
Figure 4: Master-slave concept
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5.2 SDA and SCL logic levels
SDA
SCL
START
Condition
STOP
Condition
Valid
data
Valid change
of data
The positive supply voltage to which SDA and SCL lines are pulled up (through pull-up
resistors), in turn determines the high level input for the slave devices. The sensor has
separate supply voltage VDD_IO for the SDA and SCL lines. The logic high ’1’ and logic low
’0’ levels for the SDA and SCL lines then depend on the VDD.
5.3 Communication phase
5.3.1 Idle state
During the idle state, the bus is free and both SDA and SCL lines are in logic high ’1’ state.
5.3.2 START(S) and STOP(P) condition
Data transfer on the bus starts with a START command, which is generated by the master.
A start condition is defined as a high-to-low transition on the SDA line while the SCL line is
held high. The bus is considered busy after the start condition.
Data transfer on the bus is terminated with a STOP command, which is also generated by
the master. A low-to-high transition on the SDA line, while the SCL line being high is defined
as a STOP condition. After the stop condition, the bus is again considered free and is in idle
state. Figure 5 shows the I2C bus START and STOP conditions.
Master can also send a REPEATED START (SR) command instead of STOP command.
REPEATED START condition is same as the START condition.
5.3.3 Data validity
After the start condition, one data bit is transmitted with each clock pulse. The transmitted
data is only valid when the SDA line data is stable (high or low) during the high period of the
clock pulse. High or low state of the data line can only change when the clock pulse is in low
state.
Figure 5: Data validity, START and STOP condition
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5.3.4 Byte format
R/W
7-bit slave address
LSBMSB
1 0 1 1 1 1 1
0 = Write
1 = Read
Data transmission on the SDA line is always done in bytes, with each byte being 8-bits long.
Data is transmitted with the most significant bit (MSB) followed by other bits.
If the slave cannot receive or transmit another complete byte of data, it can force the master
into a wait state by holding SCL LOW. Data transfer continues when the slave is ready which
is indicated by releasing the SCL pin.
5.3.5 Acknowledge (ACK) and No-Acknowledge (NAACK)
Each byte transmitted on the data line must follow an Acknowledge bit. The receiver (master or slave) generates an Acknowledge signal to indicate that the data byte was received
successfully and ready to receive next data byte.
After one byte is transmitted, the master generates an additional Acknowledge clock pulse
to continue the data transfer. The transmitter releases the SDA line during this clock pulse
so that the receiver can pull the SDA line to low state in such a way that the SDA line
remains stable low during the entire high period of the clock pulse. It is considered as an
Acknowledge signal.
If the receiver does not want to receive any further byte, it will not pull down the SDA line
and it remains in stable high state during the entire clock pulse. It is considered as a NoAcknowledge signal and the master can generate either a stop condition to terminate the
data transfer or a repeated start condition to initiate a new data transfer.
5.3.6 Slave address for the sensor
The slave address is transmitted after sending the start condition. Each device on the I2C
bus has a unique address. Master selects the slave by sending corresponding slave address
after the start condition. A slave address is a 7 bits long followed by a Read/Write bit.
Figure 6: Slave address format
The 7-bit slave address of the humidity sensor is 1011111b. The R/W bit determines the
data direction. ’0’ indicates a write operation (transmission from master to slave) and a ’1’
indicates a read operation (data request from slave).
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START
Condition
STOP
Condition
1...7 8 9 1...8
9
1...8 9
7-bit
Address
Read/
Write
ACK
Register
Address
ACK NACKData
7-bit slave address of the humidity sensor is 1011111b.
S
Slave address
+ Write
ACK
Register
address
DataACK ACK P
S
Slave address
+ Write
ACK
Register
address
Slave address
+ Read
ACK ACK
P
SR Data Data NACKACK
Transmission from master to slave
Transmission from slave to master
S
P
ACK
NACK
SR
START condition
STOP condition
Acknowledge
No acknowledge
Repeated start condition
a) I2C write: Master writing data to slave
b) I2C read: Master reading multiple data bytes from slave
5.3.7 Read/Write operation
Figure 7: Complete data transfer
Figure 8: Write and read operations of the sensor
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