Datasheet
HS40xxHigh-Performance Relative Humidity and Temperature Sensor with Digital Output
The HS40xx series is a highly accurate, fully
calibrated automotive-grade relative humidity andtemperature sensor. While the HS400x devices comein a standard package with open air inlet, theHS401x devices feature a hydropic membrane,making it dust resistant and waterproof with IP67
rating. Both sensor versions, waterproof and nonwaterproof, are available in two different accuracy
classes, HS40x1 and HS40x3. The MEMS sensor
features a proprietary sensor-level protection,
ensuring high reliability and long-term stability.
Integrated calibration using a NIST traceable andverified production setup that is calibrated to ISO/IEC
17025 standards and temperature-compensation
logic provides fully corrected RH and temperature
values via a standard I2C output. No user calibrationof the output data is required.
The high accuracy, fast measurement response time,and long-term stability combined with the small
package size makes the HS40xx series ideal for awide number of applications ranging from portabledevices to products designed for harshenvironments.
The HS40xx series digital sensor accurately
measures relative humidity and temperature levels.
The measured data is internally corrected andcompensated for accurate operation over a wide
range of temperature and humidity levels – user
calibration is not required.
The ultra-low power consumption, micro-Watt, makes
the HS40xx the ideal choice for portable and remoteapplications.

Physical Characteristics■

Supply voltage: 1.71V to 3.6V■

Operating temperature: -40°C to +125°C■

2.50 × 2.50 × 0.90 mm DFN-style 8-LGA package

Product Image

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Features■

Humidity range: 0% to 100%RH■

Industrial grade, JEDEC qualified, -40°C to+125°C■

Automotive grade, AEC-Q100 qualified, Grade 2,-40°C to +105°C■

NIST traceability for relative humidity andtemperature■

Hydrophobic membrane, IP67 rating (HS401x)■

Digital I2C output with CRC checksum■

RH accuracy: ±1.5%RH, typical (HS40x1)■

Temperature accuracy: ±0.2°C, typical (HS40x1,-10°C to +80°C)■

14-bit resolution: 0.04%RH, typical■

Independent programmable resolution settings:
8, 10, 12, 14 bits■

Fast RH response time: 4 seconds time constant,typical■Very low current consumption: 0.3µA average (8bit resolution, 3.3V supply), 0.62µA average (14-bit
resolution, 3.3V supply), one RH and temperature
measurement per second■

Excellent stability against aging and volatilecompounds■

Highly robust protection from harsh environmental
conditions and mechanical shock

Applications■

Climate control systems■

Instrumentation■

Home appliances■

Weather stations■

Building automation■

HVAC systems■

Medical equipment■

Data logging systems

Page 1© 2023-2024 Renesas Electronics

HS40xx Datasheet

Contents
1.

2.

3.

Pin Information .............................................................................................................................................4
1.1

Pin Assignments ...................................................................................................................................4

1.2

Pin Descriptions....................................................................................................................................4

1.3

Functional Diagram ..............................................................................................................................4

Specifications ...............................................................................................................................................5
2.1

Absolute Maximum Ratings ..................................................................................................................5

2.2

Recommended Operating Conditions...................................................................................................5

Humidity and Temperature Sensor Performance ......................................................................................6
3.1

Humidity Sensor Specification ..............................................................................................................6

3.2

Temperature Sensor Specification .......................................................................................................6

3.3

Humidity Sensor Accuracy Graphs .......................................................................................................7

3.4

Temperature and Sensor Accuracy Graphs .........................................................................................7

4.

Conditioning .................................................................................................................................................85.

PCB Layout Guidelines ................................................................................................................................86.

Application Circuit ........................................................................................................................................97.

Sensor Interface ...........................................................................................................................................9
7.1

I2C Features and Timing .......................................................................................................................9

7.2

Sensor Slave Address ........................................................................................................................10

7.3

I2C Communication .............................................................................................................................10

7.4

Measurements and Commands..........................................................................................................11
7.4.1

Performing a Hold Measurement..........................................................................................127.4.2

Performing a No-Hold Measurement ....................................................................................12

7.4.3

Calculating Humidity and Temperature Output.....................................................................13

7.4.4

Measurement Conversion Times..........................................................................................14

7.4.5

CRC Checksum Calculation .................................................................................................14

7.5

Periodic Measurement Mode ..............................................................................................................15

7.6

Alert Feature .......................................................................................................................................15

7.7

7.8

7.9

7.6.1

Alert Pin – Measurement Active ...........................................................................................16

7.6.2

Alert Pin – Humidity and Temperature Threshold Detection ................................................16

Accessing Configurable HS40xx Registers ........................................................................................18
7.7.1

Read Register Command .....................................................................................................19

7.7.2

Write Register Command .....................................................................................................19

Configuration Bits ...............................................................................................................................20
7.8.1

Setting the Measurement Resolution ...................................................................................20

7.8.2

Periodic Measurement Settings............................................................................................20

Reading the Sensor ID Number..........................................................................................................22

7.10 Resetting the Sensor ..........................................................................................................................23
8.

Soldering Information ................................................................................................................................24

9.

Storage and Handling.................................................................................................................................25

10. Quality and Reliability ................................................................................................................................25
11. Package Outline Drawings.........................................................................................................................25
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12. Marking Diagram ........................................................................................................................................25
13. Ordering Information ..................................................................................................................................25
14. Revision History .........................................................................................................................................26

FiguresFigure 1. Pin Assignments – Top View ................................................................................................................... 4
Figure 2. Functional Diagram of HS40xx ................................................................................................................ 4
Figure 3. HS40x1 RH Accuracy Tolerance at 25°C ................................................................................................ 7
Figure 4. HS40x1 RH Accuracy over Temperature ................................................................................................ 7
Figure 5. HS40x3 RH Accuracy Tolerance at 25°C ................................................................................................ 7
Figure 6. HS40x3 RH Accuracy over Temperature ................................................................................................ 7
Figure 7. HS40x3 Temperature Sensor Accuracy Tolerance ................................................................................. 7
Figure 8. HS40x1 Temperature Sensor Accuracy Tolerance ................................................................................. 7
Figure 9. Milled PCB Openings for Thermal Isolation ............................................................................................. 8
Figure 10. HS40xx Application Circuit – Top View ................................................................................................. 9
Figure 11. Timing Diagram ..................................................................................................................................... 9
Figure 12. START and STOP Condition Waveform.............................................................................................. 10
Figure 13. Typical Hold Measurement Sequence for a Humidity and Temperature Command ............................ 12
Figure 14. Typical No-Hold Measurement Sequence for a Humidity and Temperature Command ...................... 13
Figure 15. Sequence to Retrieve the Latest Results in Periodic Measurement Mode .......................................... 15
Figure 16. Sequence to Stop Periodic Measurements ......................................................................................... 15
Figure 17. Alert Pin Function ................................................................................................................................ 16
Figure 18. Alert Pin Functionality Example ........................................................................................................... 17
Figure 19. Data Returned from HS40xx when the Alert Feature is Enabled in Periodic Measurement Mode ...... 17
Figure 20. Read Register Command Sequence ................................................................................................... 19
Figure 21. Write Register Command Sequence ................................................................................................... 19
Figure 22. Read Sensor ID Command Sequence ................................................................................................ 23
Figure 23. Recommended Soldering Profile ......................................................................................................... 24

TablesTable 1. Absolute Maximum Ratings for HS40xx Sensors ..................................................................................... 5
Table 2. Operating Conditions for HS40xx Sensors ............................................................................................... 5
Table 3. Humidity Sensor Specification, TA = +25°C, VDD = 1.71V to 3.6V............................................................. 6
Table 4. Temperature Sensor Specification, TA = +25°C, VDD = 1.71V to 3.6V ...................................................... 6
Table 5. I2C Timing Parameters ........................................................................................................................... 10
Table 6. Commands Code and Description .......................................................................................................... 11
Table 7. Measurement Command Modes ............................................................................................................ 11
Table 8. Conversion Times................................................................................................................................... 14
Table 9. CRC Checksum Properties..................................................................................................................... 14
Table 10. Alert Status Bits .................................................................................................................................... 18
Table 11. Temperature and Humidity Measurement Resolution Settings............................................................. 20
Table 12. Periodic Measurement Settings ............................................................................................................ 20
Table 13. Alert Feature Settings ........................................................................................................................... 21
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1. Pin Information
1.1

Pin Assignments
4

3

2

1

7

8

9

5

6

Figure 1. Pin Assignments – Top View

1.2

Pin Descriptions

Pin Number

Pin Name

Type

1

SDA

In/Out2

NC [1]-

Connect to VSS, VDD or leave floating

3

ALERT

Out

Digital output indicating an alarm condition. Leave floating if unused.

4

SCL

In/OutSerial clock.

5

VDD

In

Supply voltage.

6

NC [1]-

Connect to VSS, VDD or leave floating.

7

NC [1]-

Connect to VSS, VDD, or leave floating.

8

VSS

In

Ground.

9

DAP-

Connect to VSS or leave floating.

1.

1.3

Description
Serial data.

“NC” stands for not connected.

Functional Diagram
Clock
Generator

Biasing

Humidity
SensorMUXADC

Calibration
Logic

I2C SerialInterface

I/O

Temperature
SensorFigure 2. Functional Diagram of HS40xx

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2. Specifications
2.1

Absolute Maximum Ratings

Caution: The absolute maximum ratings are stress ratings only. Stresses greater than those listed below cancause permanent damage to the device. Functional operation of the HS40xx at absolute maximum ratings is not
implied. Exposure to absolute maximum rating conditions might affect device reliability.
Table 1. Absolute Maximum Ratings for HS40xx Sensors
Parameter

Conditions

Minimum

Maximum

Unit

-

-0.3

3.6

V

-40

125

°C

Supply Voltage
Storage Temperature Range

2.2

Recommended 0 to 60°C

Recommended Operating Conditions

Important: The HS40xx series sensors are optimized to perform best in the more common temperature andhumidity ranges of 10°C to 50°C and 20% RH to 80% RH, respectively. If operated outside of these conditions
for extended periods, especially at high humidity levels, the sensors may exhibit an offset. In most cases, thisoffset is temporary and will gradually disappear once the sensor is returned to normal temperature and humidity
conditions. The amount of the shift and the duration of the offset vary depending on the duration of exposure andthe severity of the relative humidity and temperature conditions [1] .The time needed for the offset to disappear
can also be decreased by using the procedures described in section 4.
Table 2. Operating Conditions for HS40xx Sensors
Parameter

Condition

Minimum

TypicalMaximum

Unit

-

1.71

3.3

3.6

V

25°C

-

0.010

0.025

-40 to 125°C

-

-

2.5

8-bit resolution

0.27

0.30

0.32

10-bit resolution

0.31

0.34

0.37

12-bit resolution

0.39

0.43

0.47

14-bit resolution

0.55

0.62

0.69

8-bit resolution

-

0.64

-

10-bit resolution

-

0.80

-

12-bit resolution

-

1.04

-

14-bit resolution

-

1.70

-

-

-40

-

125

°C

Logic Voltage Level HighApplies for SDA and SCL

0.7 * VDD--

V

Logic Voltage Level Low

Applies for SDA and SCL--

0.3 * VDD

V

Operating Supply Voltage
Sleep Current

Average Current

Sleep Mode

One RH + temperature
measurement/second
VDD = 3.3V

Measurement TimeOperating Temperature Range

1.

Humidity andtemperature including
the digitalcompensation

µA

µA

ms

At TA = +25°C, VDD = +1.71V to +3.6V unless otherwise specified.

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3. Humidity and Temperature Sensor Performance
3.1

Humidity Sensor Specification
Table 3. Humidity Sensor Specification, TA = +25°C, VDD = 1.71V to 3.6V
Parameter

Condition

Minimum

TypicalMaximum

Unit

-

0

-

100

%RH

Range
Accuracy [1][2]Resolution

HS40x1

10% to 90%RH

-

±1.5

-

HS40x3

20% to 80%RH

-

±2.5

-

-

0.04

-

%RH

-

-

±1.0

%RH

-

±0.15

-

%RH

-

±0.1

-

%RH/Yr

3.0

4.0

6.0

sec

14-bitHysteresis-

Non-Linearity from Response Curve

HS40x1

10% to 90%RH

HS40x3

20% to 80%RH

Long-Term Stability-

Response Time Constant [3] (τH)
1.

20% to 80% RH Still Air

Monotonic increases from 10% to 90% RH after sensor has been stabilized at 50% RH.

2.

For more information, see section 3.3.

3.

Initial value to 63% of total variation. Response time depend on system airflow.

3.2

%RH

Temperature Sensor Specification
Table 4. Temperature Sensor Specification, TA = +25°C, VDD = 1.71V to 3.6V
Parameter

Range
Accuracy [1]Resolution

Condition

Minimum

TypicalMaximum

Unit

-

-40

-

125

°C

HS40x1-10°C to 80°C

-

±0.2

-

HS40x30°C to 70°C

-

±0.25

-

-

0.01

-

°C

14-bit°C

Response Time Constant [2] (τT)

-

-

>2.0

-

Sec.

Long-Term Stability

-

-

-

0.03

°C/Yr

Supply Voltage Dependency [3]

-

-

0.03

0.1

°C/V

1.

For more information, see section 3.4.

2.

Initial value to 63% of total variation. Response time depends on system thermal mass and air flow.

3.

Temperature accuracy can be optimized for specified supply voltages upon request.

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3.3

Humidity Sensor Accuracy Graphs

The typical relative humidity sensor accuracy tolerances are shown in the following figures.

3.4

Figure 3. HS40x1 RH Accuracy Tolerance at 25°C

Figure 4. HS40x1 RH Accuracy over Temperature

Figure 5. HS40x3 RH Accuracy Tolerance at 25°C

Figure 6. HS40x3 RH Accuracy over Temperature

Temperature and Sensor Accuracy Graphs

Figure 7. HS40x3 Temperature Sensor Accuracy
Tolerance

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Figure 8. HS40x1 Temperature Sensor Accuracy
Tolerance

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HS40xx Datasheet

4. Conditioning
After soldering or prolonged storage outside the nominal storage conditions, a conditioning routine must be
applied to ensure high sensor accuracy. Not following this routine will result in a slowly disappearing offset in therelative humidity readings. When a relative humidity sensor is exposed to the high heat associated with thesoldering process, the sensor element tends to dry out. To avoid an offset in the relative humidity readings, thesensor element must be rehydrated after the soldering process.
Recommended rehydration process:■A relative humidity of 75% RH at room temperature for at least 12 hours, or■A relative humidity of 40% to 50% RH at room temperature for 3 to 5 days

To avoid relative humidity reading offset after prolonged storage outside the recommended storage conditions,use the following procedure to recondition the humidity sensor.
1. Bake at a temperature of 100°C with a humidity < 10% RH for 10 to 12 hours.
2. Rehydrate the sensor at a humidity of 75% RH and a temperature between 20°C to 30°C for 12 to 14 hours.

5. PCB Layout Guidelines
When designing the PCB, undesired heat transfer paths to the HS40xx series must be minimized. Excessive
heat from other components on the PCB will result in inaccurate temperature and relative humidity
measurements. As such, solid metal planes for power supplies should be avoided in the vicinity of thesensor since these will act as thermal conductors. To further reduce the heat transfer from other components on
the board, openings can be milled into the PCB as shown in Figure 9.

Figure 9. Milled PCB Openings for Thermal Isolation

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6. Application Circuit

Figure 10. HS40xx Application Circuit – Top View

7. Sensor Interface
The HS40xx series sensor uses a digital I2C-compatible communication protocol. To accommodate multiple
devices, the protocol uses two bi-directional open-drain lines: the Serial Data Line (SDA) and the Serial ClockLine (SCL). Pull-up resistors to VDD are required. Several slave devices can share the bus; however, only one
master device can be present on the line.

7.1

I2C Features and Timing

The HS40xx series sensor operates as a slave device on the I2C bus with support for 100kHz and 400kHz bit
rates. Each transmission is initiated when the master sends a 0 START bit (S), and the transmission is
terminated when the master sends a 1 STOP bit (P). These bits are exclusively transmitted while the SCL line is
high.

SDA

tSUDATtLOW

tBUS

tHDSTASCLtHDSTAtHDDATtHIGHtSUSTAtSUSTO

Figure 11. Timing Diagram

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Table 5. I2C Timing Parameters
Parameter

SymbolMinimum

TypicalMaximumUnit

SCL Clock Frequency

fSCL

0

-

400

kHz

START Condition Hold Time Relative to SCL Edge

tHDSTA

0.1

-

-

µs

Minimum SCL Clock LOW Width [1]

tLOW

0.6

-

-

µs

Minimum SCL Clock HIGH Width [1

tHIGH

0.6

-

-

µs

START Condition Setup Time Relative to SCL EdgetSUSTA

0.1

-

-

µs

Data Hold Time on SDA Relative to SCL EdgetHDDAT

0

-

0.5

µs

Data Setup Time on SDA Relative to SCL EdgetSUDAT

0.1

-

-

µs

STOP Condition Setup Time on SCL

tSUSTO

0.1

-

-

µs

Bus Free Time Between STOP Condition and START Condition

tBUS

1

-

-

µs

1.

7.2

Combined LOW and HIGH widths must equal or exceed the minimum SCL period.

Sensor Slave Address

The HS40xx series default I2C address is 54HEX. The device will respond only to this 7-bit address.

7.3

I2C Communication

The sensor transmission is initiated when the master sends a 0 START bit (S). The transmission is terminatedwhen the master sends a 1 STOP bit (P). These bits are only transmitted while the SCL line is HIGH (see Figure
12 for waveforms).
Once the START condition has been set, the SCL line is toggled at the prescribed data rate, clocking
subsequent data transfers. Data on the SDA line is always sampled on the rising edge of the SCL line and mustremain stable while SCL is HIGH to prevent false START or STOP conditions.
START Condition
SCL

STOP Condition
SCL

START

SDA

STOP

SDA

Figure 12. START and STOP Condition Waveform

After the START bit, the master device sends the 7-bit slave address (see section 7.2) to the HS40xx, followedby the read/write bit, which indicates the transfer direction of any subsequent data. This bit is set to 1 to indicate
a read from slave to master or set to 0 to indicate a write from master to slave.
All transfers consist of 8 bits and a response bit: 0 for Acknowledge (ACK) or 1 for Not Acknowledge (NACK).
After the ACK is received, another data byte can be transferred or the communication can be stopped with a
STOP bit.

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The HS40xx series sensors are equipped with different commands to configure the chip and to performmeasurement as described in Table 6.
Table 6. Commands Code and Description
Command Code (HEX)

Description

0xE3

Hold Temperature Measurement

0xF3

No-hold Temperature Measurement

0xE5

Hold Humidity and Temperature Measurement

0xF5

No-hold Humidity and Temperature Measurement

0xA7

Read Register

0xA6

Write Register0x30

Stop Periodic Measurements

0xD7

Read Sensor ID

The Hold and No-hold commands are described in section 7.4, and the read and write register commands aredescribed in section 7.7. The HS40xx sensor can measure only temperature or both humidity and temperature
as described in Table 7. Both options return fully calibrated measurements that can be converted to humidity andtemperature readings using the equations in section 7.4.3. To soft reset the sensor, see section 7.10.
Table 7. Measurement Command Modes
Measurement
Command Mode

Description

Number of Data Bytes
Sent on the I2C Bus

Temperature

The chip only measures temperature and sends the 14-bit result once themeasurement is complete.

2 bytes + 1 byte CRC

Humidity andTemperature

The chip measures humidity and temperature and sends the 14-bit humidity
result followed by the 14-bit temperature result once the measurement iscomplete.

4 bytes + 1 byte CRC

7.4

Measurements and Commands

There are two types of measurement commands:
1. Hold Measurement commands – The HS40xx series sensor holds the SCL line low during the measurement
and releases the SCL line when the measurement is complete. This lets the master know exactly when themeasurement has finished. Using this mode will prevent the master from communicating with any otherslave until the measurement is complete. Note that the minimum frequency for the SCL clock in this mode is
200kHz.
2. No-hold Measurement commands – The HS40xx series sensor does not hold the SCL line low, and themaster is free to initiate communication with other slaves while the chip is performing the measurement. To
obtain the measurement data, the master must request the result from the chip after the expected
conversion time which depends on the measurement resolution as summarized in section 7.4.4. There is no
minimum clock frequency when in this mode.

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7.4.1

Performing a Hold Measurement

A hold measurement sequence consists of the following steps, as displayed in Figure 13. The minimum SCL
clock frequency in this mode is 200kHz.
1. Wake up the HS40xx series sensor from sleep mode by sending its I2C address with a write bit and initiate ameasurement by sending the desired hold measurement command.
2. Change the direction of communication by sending a start bit, the HS40xx I2C address, and a read bit. The
SCL line is held low by the sensor during the measurement process, which prevents the master frominitiating any communications with other slaves on the bus.
Once the requested measurement is completed by the HS40xx series sensor, the SCL line is released and thechip waits for the SCL clock signal to send the results. The sensor will then transmit the requested measurement
data on the bus for the master to capture and enters sleep mode again after 20µs.

Figure 13. Typical Hold Measurement Sequence for a Humidity and Temperature Command

7.4.2

Performing a No-Hold Measurement

A no-hold measurement sequence consists of the following steps, as displayed in Figure 14.
1. Wake up the HS40xx series sensor from sleep mode by sending its I2C address with a write bit and initiate ameasurement by sending the desired no-hold measurement command.
2. To read the result from the HS40xx series sensor, the master has to send the chip its I2C address and aread bit. If the measurement is completed and the result is ready, the chip will send an ACK bit and start tosend the result over the bus and then enter sleep mode again after 20µs. If the measurement is still inprogress, the chip will send a NACK bit and the master will need to try to read the result again.

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Figure 14. Typical No-Hold Measurement Sequence for a Humidity and Temperature Command

7.4.3

Calculating Humidity and Temperature Output

As indicated in Table 7, the measurement data can be either two or four bytes long depending on whether atemperature measurement or a humidity and temperature measurement was initiated. The most significant bit of
the reading is sent first followed by the least significant bits. The humidity and temperature measurements arealways scaled up to a 14-bit value regardless of the selected resolution of the sensor. The relative humidity (inpercent) and the temperature (in degrees Celsius) are obtained as follows:
The relative humidity (in percent) and the temperature (in degrees Celsius) are calculated with Equation 1 andEquation 2, respectively.

𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻 [%𝑅𝑅𝑅𝑅] =𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 [°𝐶𝐶] =R36DS0036EU0103 Rev.1.03
Jun 14, 2024

𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻[13: 0]∗ 100
214 − 1

𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 [13: 0]∗ 165 − 40
214 − 1Equation 1

Equation 2

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HS40xx Datasheet

7.4.4

Measurement Conversion Times

The HS40xx series sensors are designed to have relatively fast conversion times. The conversion time depends
on the resolution of the measurement and the command type (temperature or humidity and temperature).
Table 8 summarizes the conversion times for different resolutions.
Table 8. Conversion Times
Measurement

Temperature

Humidity and Temperature [1]

1.

7.4.5

Resolution (bits)

Measurement Time (ms)

8

0.37

10

0.45

12

0.60

14 (default)

0.91

8

0.64

10

0.80

12

1.04

14 (default)

1.70

Assuming the same resolution settings for both humidity and temperature measurements.

CRC Checksum Calculation

An 8-bit CRC checksum is transmitted after each measurement so that the user can check for data corruption
during communications if desired. The properties of the CRC algorithm used are summarized in Table 9, and the
CRC is based on all 4 bytes of measurement data (2 bytes of humidity data followed by 2 bytes of temperaturedata). For temperature-only measurements, the 2 bytes of humidity data are set to be all zeros for the CRC
calculation.
Table 9. CRC Checksum Properties
Property

Value

Input Data Width

32 bits

CRC Width

8 bitsPolynomial

0x1D (x8 + x4 + x3 + x2 + 1)

Initial Value

0xFF

Final XOR Value

0x00

Reflect Input

No

Reflect Output

No

ExampleCRC (0x05800580) = 0xF2

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7.5

Periodic Measurement Mode

The HS40xx sensors can also be configured to measure at regular intervals without user intervention, and theprocess to enable this mode is described in section 7.8.2. In this mode, the user can read the latest relative
humidity / temperature data by issuing a data fetch sequence, which consists of sending the HS40xx I2C address
with a read bit. The sensor will then send the latest measurement result over the I2C bus. The data fetch
sequence is displayed in Figure 15.

Figure 15. Sequence to Retrieve the Latest Results in Periodic Measurement Mode

The frequency of the periodic measurements can be set using the configuration registers. Section 7.7 describes
how these registers are accessed, and section 7.8.2 provides the register settings needed to configure andactivate the periodic measurements.
When the periodic measurement mode is active, the only commands the chip will respond to are the data fetchcommand, and a command to stop the periodic measurements. The sensor will not enter sleep mode while inperiodic measurement mode. The command to stop periodic measurements is issued by sending the I2C
address with a write bit, followed by the command 0x30, as shown in Figure 16. Once the periodic
measurements have been stopped, the chip returns to sleep and is ready to accept all valid I2C commands.

S1

0 1 0 1 0 0 0
I2C Address (7 bits) + write bit

ACK

0 0 1 1 0 0 0 0 ACK
Stop Periodic Meas. Command (0x30)

P

Figure 16. Sequence to Stop Periodic Measurements

7.6

Alert Feature

The HS40xx sensors have an optional Alert feature that can be configured in the following two ways:
1. The Alert pin can be used to indicate when a measurement is active in periodic measurement mode. This is
the default behavior of the Alert pin upon power-up.
2. The Alert pin can be used to trigger an interrupt on the system microcontroller so an appropriate action canbe taken if the temperature or humidity is outside of the desired limits.
These features are described in the following two sub-sections.

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7.6.1

Alert Pin – Measurement Active

The default behavior of the Alert pin is to indicate when a measurement is active if periodic measurement modeis used. Upon power-up, the Alert pin will have a logic high level. When periodic measurement mode isactivated, the Alert pin will have a logic low level between measurements and a logic high during measurements.
This behavior is shown in Figure 17, and the Alert pin will exhibit this functionality when the temperature andhumidity alerts are disabled (see Table 13).
If periodic measurement mode is not active, the Alert pin will remain at a logic high level.

Alert Pin Output

Measurement in Progress

Stateof Alert
pin atpowerup

Periodic
Measurement
Mode ActivatedTime

Figure 17. Alert Pin Function

7.6.2

Alert Pin – Humidity and Temperature Threshold Detection

The Alert pin can also be configured to send a signal when a humidity / temperature threshold is exceeded, andthe system needs to respond. In this mode, the Alert feature has a programmable threshold, polarity, andhysteresis, and can apply to both temperature and humidity measurements. An example of the functionality of
the Alert feature is displayed in Figure 18.

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HS40xx Datasheet

Temperature or Relative Humidity

Trigger Threshold - High Alert

Reset Threshold - High Alert

Reset Threshold - Low Alert

Alert Pin (Active High)

Trigger Threshold - Low Alert

Figure 18. Alert Pin Functionality Example

The registers used to enable the Alert feature and the temperature / humidity thresholds are shown in Table 11.
When the Alert feature is enabled for either humidity or temperature in periodic measurement mode, anadditional status byte will precede the measurement values. The format of the bits are returned from the HS40xx
sensor when any Alert is enabled as shown in Figure 19.

Figure 19. Data Returned from HS40xx when the Alert Feature is Enabled in Periodic Measurement Mode

The meaning of the Alert status bits are defined in Table 10.

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Table 10. Alert Status Bits

7.7

Status Bit

Meaning

TH

High (0b1) if the Temperature High Alert is triggered

TL

High (0b1) if the Temperature Low Alert is triggered

HH

High (0b1) if the Humidity High Alert is triggered

HL

High (0b1) if the Humidity Low Alert is triggered

Accessing Configurable HS40xx Registers

The HS40xx measurement settings can be changed by accessing the appropriate configuration registers andaltering their values. This can be done by issuing a Write Register command. A Read Register command is alsoavailable to read the configuration register values. These commands are described in this section, and theconfiguration registers and settings are described in section 7.8.
While accessing specific configuration bits in any register, all the other bits in that register must be left
unchanged. To write a specific bit/bits in a register, the process is as follows:
1. Read the entire configuration register using the sequence described in section 7.7.1.
2. Mask the register such that only the required bits are changed according to the configuration parameters in
section 7.8.
3. Write the new register back to the appropriate address using the Write Register command sequencedescribed in section 7.7.2.
All configuration registers will be reset to their default values if the power supply to the chip is cut off.

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HS40xx Datasheet

7.7.1

Read Register Command

A Read Register sequence consists of the following steps, as illustrated in Figure 20.
1. Wake up the HS40xx series sensor from sleep mode by sending its I2C address with a write bit and initiate a
Read Register command by sending the command 0xA7.
2. Send the address of the register to be read.
3. Change the direction of communication by sending the HS40xx I2C address and a read bit. The chip will
send the data stored in this register, after which the master replies with a NACK and a STOP bit.

Figure 20. Read Register Command Sequence

7.7.2

Write Register Command

A Write Register sequence consists of the following steps, as illustrated in Figure 21.
1. Wake up the HS40xx series sensor from sleep mode by sending its I2C address with a write bit and initiate a
Write Register command by sending the command 0xA6.
2. Send the address of the register to write.
3. Send the data to be stored in this register followed by a STOP bit.

Figure 21. Write Register Command Sequence

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7.8

Configuration Bits

7.8.1

Setting the Measurement Resolution

The HS40xx can be configured to perform measurements at different humidity and temperature resolutions byusing the Read and Write Register commands with the appropriate register address. There are four separate
resolution settings for the temperature and humidity measurements, as summarized in Table 11.
Table 11. Temperature and Humidity Measurement Resolution Settings
Setting

Register Address (HEX)

Bits

Description
0b00 for 8 bits

Resolution for Temperature
Measurement

0x00

0b01 for 10 bits

1:0

0b10 for 12 bits
0b11 for 14 bits (default)
0b00 for 8 bits

Resolution for Humidity
Measurement

0x00

0b01 for 10 bits

3:2

0b10 for 12 bits
0b11 for 14 bits (default)

7.8.2

Periodic Measurement Settings

The registers that are used to activate and configure the periodic measurement settings are shown in Table 12.
Table 12. Periodic Measurement Settings
Setting

Register Address (HEX)

Bits

Activate Periodic
Measurements

0x02

7

Description
0b0 when periodic measurements are deactivated
0b1 to activate periodic measurements
0b00 for a measurement every 0.5s

Frequency of Periodic
Measurements

0x02

5:4

0b01 for a measurement every 1s (default)
0b10 for a measurement every 2.5s

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Table 13. Alert Feature Settings

Setting

Register
Address
(HEX)

Bits

Alert Pin Polarity In
Humidity/TemperatureThreshold Detection Mode

0x02

0

Description
0b1 = Alert pin is active high when triggered (default)
0b0 = Alert pin is active low when triggered
Enable the Alert feature when thresholds are surpassed as follows:

Alert Enable Settings

0x03

3:0

Bit 0 = RH Low alert enableBit 1 = RH High alert enableBit 2 = Temperature Low alert enable
Bit 3 = Temperature High alert enable
Setting a bit to 0b1 means this specific alert condition is enabled andsetting a bit to 0b0 means this specific alert condition is disabled.
Registers 0x08, 0x07 set the threshold for when the “Temperature High”
alert is triggered. When the measured temperature goes above the value
in this register, the Alert pin will be triggered.

Trigger Threshold for
Temperature High Alert

The temperature used for the threshold is composed of 14 bits as follows:
0x08, 0x07

13:0
0

0's

0

Register 0x08
0 0 0 1 0 1
Trigger Threshold [13:8]

1

Register 0x07
0 0 0 0 0 0
Trigger Threshold [7:0]0This 14-bit value is converted into a temperature threshold using the same
conversion equation shown in section 7.4.3.
Registers 0x06, 0x05 set the threshold for when the “Temperature High”
alert condition is reset. After the alert is triggered, it will only be reset after
the measured temperature goes below the value in this register.
The temperature used for the threshold is composed of 14 bits as follows:
Reset Threshold for
Temperature High Alert

0x06, 0x05

13:0
0

0's

0

Register 0x06
0 0 0 1 0 1
Reset Threshold [13:8]

1

0Register 0x05
0 0 0 0 0
Reset Threshold [7:0]0This 14-bit value is converted into a temperature threshold using the same
conversion equation shown in section 7.4.3.
Registers 0x0A, 0x09 set the threshold for when the “Temperature Low”
alert is triggered. When the measured temperature goes below the value
in this register, the Alert pin will be triggered.
The temperature used for the threshold is composed of 14 bits as follows:
Trigger Threshold for
Temperature Low Alert

0x0A, 0x09

13:0
0

0's

0

Register 0x0A
0 0 0 1 0 1
Trigger Threshold [13:8]

1

Register 0x09
0 0 0 0 0 0
Trigger Threshold [7:0]0This 14-bit value is converted into a temperature threshold using the same
conversion equation shown in section 7.4.3.
Registers 0x0C, 0x0B set the threshold for when the “Temperature Low”
alert condition is reset. After the alert is triggered, it will only be reset after
the measured temperature goes above the value in this register.
The temperature used for the threshold is composed of 14 bits as follows:
Reset Threshold for
Temperature Low Alert

0x0C, 0x0B

13:0
0

0's

0

Register 0x0C
0 0 0 1 0 1
Reset Threshold [13:8]

1

0Register 0x0B
0 0 0 0 0
Reset Threshold [7:0]0This 14-bit value is converted into a temperature threshold using the same
conversion equation shown in section 7.4.3.

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Setting

Register
Address
(HEX)

Bits

Description
Registers 0x10, 0x0F set the threshold for when the “RH High” alert istriggered. When the measured RH goes above the value in this register,
the Alert pin will be triggered.

Trigger Threshold for
Relative Humidity HighAlert

The humidity used for the threshold is composed of 14 bits as follows:
0x10, 0x0F

13:0
0

0's

Register 0x10
0 0 0 1 0 1
Trigger Threshold [13:8]

0

1

Register 0x0F
0 0 0 0 0 0
Trigger Threshold [7:0]0This 14-bit value is converted into a humidity threshold using the same
conversion equation shown in section 7.4.3.
Registers 0x0E, 0x0D set the threshold for when the “RH High” alertcondition is reset. After the alert is triggered, it will only be reset after themeasured RH goes below the value in this register.
Reset Threshold for
Relative Humidity HighAlert

The humidity used for the threshold is composed of 14 bits as follows:
0x0E, 0x0D

13:0
0

0's

Register 0x0E
0 0 0 1 0 1
Reset Threshold [13:8]

0

1

0

Register 0x0D
0 0 0 0 0
Reset Threshold [7:0]0This 14-bit value is converted into a humidity threshold using the same
conversion equation shown in section 7.4.3.
Registers 0x12, 0x11 set the threshold for when the “RH Low” alert istriggered. When the measured RH goes below the value in this register,
the Alert pin will be triggered.
Trigger Threshold for
Relative Humidity Low
Alert

The humidity used for the threshold is composed of 14 bits as follows:
0x12, 0x11

13:0
0

0's

0

Register 0x12
0 0 0 1 0 1
Trigger Threshold [13:8]

1

Register 0x11
0 0 0 0 0 0
Trigger Threshold [7:0]0This 14-bit value is converted into a humidity threshold using the same
conversion equation shown in section 7.4.3.
Registers 0x14, 0x13 sets the threshold for when the “RH Low” alertcondition is reset. After the alert is triggered, it will only be reset after themeasured RH goes above the value in this register.
Reset Threshold for
Relative Humidity Low
Alert

The humidity used for the threshold is composed of 14 bits as follows:
0x14, 0x13

13:0
0

0's

0

Register 0x14
0 0 0 1 0 1
Reset Threshold [13:8]

1

0Register 0x13
0 0 0 0 0
Reset Threshold [7:0]0This 14-bit value is converted into a humidity threshold using the same
conversion equation shown in section 7.4.3.

7.9

Reading the Sensor ID Number

The sensor ID is a 32-bit number that can be used to identify a specific device. Each sensor has a unique ID thatcan be used for traceability. The sequence to read the sensor ID is as follows:
1. Wake up the HS40xx series sensor from sleep mode by sending its I2C address with a write bit and initiate a
Read Sensor ID command by sending the command 0xD7.
2. Change the direction of communication by sending the HS40xx I2C address and a read bit. The SCL line isheld low by the sensor while it retrieves the ID from internal memory to prevent data corruption. The sensor
takes approximately 10µs to retrieve the ID from internal memory.

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HS40xx Datasheet
3. Once the request is completed by the HS40xx, the SCL line is released and the chip waits for the SCL clock
signal to send the results. The sensor will then transmit the 4-byte sensor ID on the bus for the master tocapture, MSB first.
The command sequence to read the sensor ID is displayed in Figure 22.

Figure 22. Read Sensor ID Command Sequence

7.10 Resetting the Sensor
With the command 0xFE, it is possible to soft reset the HS40xx. The reset will affect all writeable registers andsets them back to the default value. To use this command, ensure that the following conditions are met:
1. If the user initiates a measurement, they must read the measurement data before issuing the soft reset
command.
2. If the user has the HS40xx in Periodic Measurement Mode, they must escape the “Periodic Measurement
Mode” before issuing the soft reset command. This can be achieved by sending the “Stop Periodic
Measurement” command.
To reset the sensor, use the following sequence:
1. Wake up the HS40xx series sensor from sleep mode by sending its I2C address with a write bit.
2. Send the soft reset command 0xFE.
After sending the reset command, wait for at least 500ms before starting to communicate with the HS40xx. The
sensor will behave like it was just powered on.

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HS40xx Datasheet

8. Soldering Information
This section discusses soldering considerations for the HS40xx.
Standard reflow ovens can be used to solder the HS40xx series sensor to the PCB. The peak temperature (Tp)for use with the JEDEC J-STD-020D standard soldering profile is 260°C. For manual soldering, the contact timemust be limited to 5 seconds at up to 350°C. In either case, if solder paste is used, it is recommended to use“no-clean” solder paste to avoid the need to wash the PCB.
When a relative humidity sensor is exposed to the high heat associated with the soldering process, the sensor
element tends to dry out. To avoid an offset in the relative humidity readings, the sensor element must be
rehydrated after the soldering process. Care must also be taken when selecting the temperatures and durations
involved in the soldering process to avoid irreversibly damaging the sensor element.
The recommended soldering profile for a lead-free (RoHS-compliant) process is shown below.

Figure 23. Recommended Soldering Profile

Important: Ensure this temperature profile is measured at the sensor itself. Measuring the profile at a larger
component with a higher thermal mass means the temperature at the small sensor will be higher than expected.
For manual soldering, the contact time must be limited to 5 seconds with a maximum iron temperature of 350°C.
In either case, a board wash after soldering is not recommended. Therefore, if a solder paste is used, it isstrongly recommended that a “no-clean” solder paste is used to avoid the need to wash the PCB.
After soldering, the recommended rehydration process in section 4 should be performed; otherwise, there may
be an initial offset in the relative humidity readings, which will slowly disappear as the sensor get exposed toambient conditions.

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HS40xx Datasheet

9. Storage and Handling
Recommendation: Once the sensors are removed from their original packaging, store them in metal-inantistatic bags.
Avoid using polyethylene antistatic bags as they may affect sensor accuracy.
The nominal storage conditions are 10°C to 50°C and humidity levels within 20% to 60%RH. If stored outside ofthese conditions for extended periods of time, the sensor readings may exhibit an offset. The sensor can bereconditioned and returned to its calibration state by applying the procedure described in section 4.

10. Quality and Reliability
The HS40xx series is available as a qualified product for consumer and industrial market applications. All data
specified parameters are guaranteed if not stated otherwise.

11. Package Outline Drawings
The package outline drawings are located at the end of this document and are accessible from the Renesas
website. The package information is the most current data available and is subject to change without revision ofthis document.

12. Marking Diagram
40xx

Inlet (HS400x only)
Inlet with membrane(HS401x only)

YWSN

■

Line 1: Sensor type (for example, 4011)■

Line 2:●First character: Year (for example, 3 = 2023)●

Second character: Week code (for example, X = 31)●

Third and fourth character: Test Release Sequence
NumberPin 1 dot

13. Ordering Information
Part Number
HS4001HS4003HS4011

Package Description
Digital Relative Humidity and Temperature Sensor,±1.5%RH (typical), 2.50 × 2.50 × 0.90 mm, 8-LGA
Digital Relative Humidity and Temperature Sensor,±2.5%RH (typical), 2.50 × 2.50 × 0.90 mm, 8-LGA
Digital Relative Humidity and Temperature Sensor, withmembrane.

Carrier Type

Temperature Range

Reel-40°C to +125°C

Reel-40°C to +125°C

Reel-40°C to +125°C

Reel-40°C to +125°C±1.5%RH (typical), 2.50 × 2.50 × 0.90 mm, 8-LGA

HS4013

Digital Relative Humidity and Temperature Sensor, withmembrane.
±2.5%RH (typical), 2.50 × 2.50 × 0.90 mm, 8-LGA

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HS40xx Datasheet

14. Revision History
Revision

Date

1.03

Jun 14, 2024

Description
Updated PCB Layout Guidelines section.
 Changed the order of various sections.
 Updated the “Product Image” on front page.

1.02

Mar 25, 2024

 Changed Pin Assignments diagram to “Top View” from “Bottom View”.
 Added I²C voltage specifications to Table 2.
 Updated the bit description for 0x02 in Table 13.
 Added Functional Diagram.
 Added the Conditioning section.

1.01

Nov 3, 2023

 Added the “Resetting the Sensor” section.
 Updated the “Pin Assignments” and “Pin Descriptions” sections.
 Updated performance characteristics.
 Updated “Soldering Information” and “Storage and Handling” sections.

1.00

Aug 11, 2023

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Initial release.

Page 26

Package Outline Drawing
Package Code: LVG8D3
8-LGA 2.50 x 2.50 x 0.90 mm Body, 0.50mm Pitch
PSC-4861-03, Revision: 03 Date Created: Aug 27, 2024

0.25 X 0.35 (8x)2.50±0.10
PIN1
CORNER(2.30)

A(0.38)PIN1
CORNER(0.10)

0.250 ∠45°
(2.30)

2.50±0.10

0.852±0.10

1.95

0.64
Ø0.30
HOLE
0.64

(R0.13)0.50(R0.25)1.80±0.10

TOP VIEW

Solde rmask Opening

BOTTOM VIEW

0.90±0.10
0.08 C
Seating Plane(0.18)C

Solder mask

Package Edge

SIDE VIEW

Exposed Metal

Detail A
0.25

NOTES:
0.852

1.60

2.60

1.
2.
3.
4.

0.50
0.50

Package Outline

1.80

RECOMMENDED LAND PATTERN(PCB Top View, NSMD Design)© Renesas Electronics Corporation

JEDEC compatible
All dimensions are in mm, angles in degrees.
Use ±0.05 mm for non-toleranced dimensions.
Numbers in ( ) are for reference only.

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