SENSIRION SHT45 Digital Humidity and Temperature Sensor User Guide

User Guide for SENSIRION models including: SHT45, SHTW2, SHT4x, SHT45 Digital Humidity and Temperature Sensor, Digital Humidity and Temperature Sensor, Humidity and Temperature Sensor, Temperature Sensor, Sensor

SHT45-±1.0% RH / ±0.1°C Digital humidity and temperature sensor

SHTW2 – SHT4x Transition Guide

File Info : application/pdf, 8 Pages, 347.88KB

HT Transition Guide SHTW2-SHT4x

SHTW2 SHT4x Transition Guide
Boarding the new flagship RH/T sensor generation
SHTW2

SHT4x

Improved accuracy, power consumption, and robustness Powerful internal heater for self-decontamination Superior versatility and technology from two decades of sensor development No fine print PCB necessary

Abstract Once introduced as the smallest digital humidity (RH) and temperature (T) sensor, the SHTW2 enabled outstanding sensing performance in a small package for several years. Sensirion now proudly presents its all new flagship sensors from the SHT4x family, which profits from about two decades of RH/T sensor development. Dedicated to best-in-class performance, low power consumption, smallest footprint, and attractive pricing, our new SHT4x sensors are the products of choice for many SHTW2 applications. In particular, except for size, the SHT4x outperforms the SHTW2 in every aspect and offers versatile add-ons, such as a powerful heater for selfdecontamination, conformal coating protection, or filter membranes, previously impossible. Last-Time-Buy for the SHTW2 is 31.05.2021 and Last-Time-Delivery 31.12.2021. SHT4x sensors will be available for purchase in Q1/2021, release information and samples available in Q4/2020. Important changes

Parameter

SHTW2

SHT4x

Dimensions (mm3)

1.3 0.7 0.5

1.5 1.5 0.5

Pin assignment

Comparable

Interface

I2C, single address

I2C, multiple addresses

Supply voltage (V)

1.62 1.98

1.08 5.51

Av. current (A @ 1Hz)

4.8

0.6

Typ. RH accuracy (%RH)

±3.0

±1.8 ±1.0

Typ. T accuracy (°C)

±0.3

±0.2 ±0.1

Response time 63% (s)

Filter membrane

Not available

Available

Conformal coating

Not possible

Possible

Additional features

Powerful heater with T60°C,

Full condensation robustness

1 SHT4xI has a higher possible supply voltage up to 5.5V

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Table of Contents

1 General

2 Performance Comparison

2.1 Relative Humidity and Temperature

2.2 Electrical Characteristics

2.3 Timing Specifications

3 Flagship SHT4x Feature: Built-In Heater

4 Package Design Differences

5 Communication Compatibility

6 Quality and Material Contents

7 Further Information

8 Revision History

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1 General

The SHTW2 reaches its End of Life and will not be shipped anymore after 31.12.2021 (Last-Time-Buy 31.05.2021). This document aims to provide a high level guideline to replace SHTW2 with sensors from the SHT4x family and outlines important differences to be considered in design-in processes.
2 Performance Comparison

2.1 Relative Humidity and Temperature

Parameter Relative humidity RH accuracy2 High repeatability3 Resolution4 Hysteresis Specified range5 Response time7 Long-term drift8 Condensation behavior Temperature T Accuracy1 High repeatability2 Resolution3 Specified range4 Response time9 Long-term drift10

Conditions

SHTW2

SHT4x

Typ. -
extended6 63% Typ.
Droplet formation

3 0.1 0.01 1 0 100 8 <0.25 Slight signal drop

1.0 ... 1.8 0.08 0.01 1
0 100 4
<0.25 No signal drop

Typ. -
63% Typ.

0.3 0.1 0.01 -30 +100 <5 30 < 0.02

0.1 0.04 0.01 -40 +125
2 < 0.01, < 0.03

Units
%RH %RH %RH %RH %RH
s %RH/y
-
°C °C °C °C s °C/y

Table 1. Humidity and temperature specifications of the SHTW2 and SHT4x, where bold values highlight important differences. For further details, kindly refer to the SHTW2 and SHT4x datasheets.

2 For definition of typ. accuracy, please refer to the document "Sensirion Humidity Sensor Specification Statement". 3 The stated repeatability is 3 times the standard deviation (3) of multiple consecutive measurement values at constant conditions and is a measure for the noise
on the physical sensor output. Different repeatability commands are listed in Table 5. 4 Resolution of A/D converter. 5 Specified range refers to the range for which the humidity or temperature sensor specification is guaranteed. 6 For details about recommended humidity and temperature operating range, please refer to the SHT4x Datasheet. 7 Time for achieving 63% of a humidity step function, valid at 25°C and 1 m/s airflow. Humidity response time in the application depends on the design-in of the
sensor. 8 Typical value for operation in normal RH/T operating range. Max. value is < 0.5 %RH/y. Value may be higher in environments with vaporized solvents, out-gassing
tapes, adhesives, packaging materials, etc. For more details, please refer to Handling Instructions. 9 Temperature response time depends on heat conductivity of sensor substrate and design-in of sensor in application. 10 Max. value is < 0.04°C/y. The long-term drift for SHT43 is < 0.01 C/y

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2.2 Electrical Characteristics

Parameter
Supply voltage Power-up/down level
Supply current (heater not activated)
Power consumption
Low level input voltage
High level input voltage
Application circuit design

Symbol VDD VPOR
IDD
VIL VIH -

Conditions
Static power supply Idle state
Measurement Average Average
-

SHTW2

Min Typ. Max

1.62 1.8 1.98

1.05 1.2 1.35

0.7

1.5

385 465

4.8

8.6

SHT4x

Min Typ. Max

1.08 3.3

3.6

0.6

1.08

0.08

320

- 0.4 (low) 2.2 (high)

- 0.5 (low) 2.6 (high)

-0.5

0.3 VDD 0

0.3 VDD

0.7 VDD

VDD(max) +0.5

0.7 VDD

VDD

Identical, for details see SHTW2 or SHT4x datasheet

Units
V V µA µA µA
µW
V
V
-

Table 2. Key electrical specifications of the SHTW2 and SHT4x, where bold values highlight important differences. For further details, kindly refer to the SHTW2 and SHT4x datasheets.

2.3 Timing Specifications

Parameter

Symbol Conditions

Power-up time

tPU

After hard reset, VDD VPOR

Soft reset time

tSR

After soft reset

Measurement duration

tMeas

Medium repeatability

Heater-on duration tHeater

SHTW2 Min Typ. Max

0.18 0.24

0.17 0.23

10.8 14.4

SHT4x Min Typ. Max

3.7

4.5

0.1

Units
ms ms ms s

Table 3. Key timing specifications of the SHTW2 and SHT4x, where bold values highlight important differences. For further details, kindly refer to the SHTW2 and SHT4x datasheets.

3 Flagship SHT4x Feature: Built-In Heater
The SHT4 sensor incorporates a powerful on-chip heater, which can be used for self-decontamination, e.g. in environments with solvents present, and periodical creep compensation in prolonged application in highest humidity. It provides an over-temperature of about 60 °C and can be switched on by the command specified in Table 5, after which the heater will run for 1 second. After 1 second, a temperature and humidity measurement is started and the heater will be automatically turned off after the measurement is finished. This safety feature prevents permanent turn-on of the heater. There is no dedicated command to turn off the heater since it has an internal timer set to 1s after which it is switched off automatically. If higher heating temperatures than achievable in 1 second are desired, consecutive heating commands need to be sent to the sensor.

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4 Package Design Differences

The SHT4x comes in a new open-cavity dual flat no lead (DFN) package design in order to enable additional features, such as conformal coating, protection cover, and filter membrane compatibility. In contrast to the SHTW2, the humidity sensor opening is centered on the top side of the SHT4x package (see Figures 1,2), which not only facilitates the soldering process, but also improves the sensor's resistance to contamination during PCB assembly. Instead of featuring solder balls, the exposed bottom side of the DFN package exposes metallic contacts, which are Ni/Pd/Au coated, while the side walls of the contacts are bare copper.

Parameter Size
Sensor opening
Protection compatibility
Pin Layout Necessity for fine-print PCB
Pin Assignment
Pin Size Pin Pitch Pin Material Housing Material

Units mm
-
-
-

SHTW2 1.3 x 0.7 x 0.5
Bottom
none
2 x 2 pins yes

SHT4x 1.5 x 1.5 x 0.5
Top Compatible with conformal
coating, Compatible with filter
membranes 2 x 2 pins
no

Comment For details, see Figures 1,2.

VDD
-
SCL

VSS SDA SDA SCL

VSS Drawings not to scale.

VDD: Supply voltage

SCL: Serial clock

SDA: Serial data bidirectional

VDD

VSS: Ground

Diameter: 0.2

0.4

Si- and Pb-free solder balls

Epoxy back-side cover

0.3 x 0.3 0.8
Ni/Pd/Au coated Cu Epoxy housing

Table 4. Key package differences between the SHTW2 and SHT4x. For further details, kindly refer to the SHTW2 and SHT4x datasheets.

Figure 1. Dimensional drawing of the SHTW2 including (units mm).

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Figure 2. Dimensional drawing of SHT4x including package tolerances (units mm).

5 Communication Compatibility

Both chips feature the I2C communication protocol, however, while the SHTW2 has a fixed I2C address, the SHT4x features a default I2C address (0x44) and alternative addresses for high flexibility in all applications. Addressing a specific SHT4x sensor is done by sending its 7-bit I2C address followed by an eighth bit, denoting the communication direction: "Zero" indicates transmission to the sensor, i.e. "write", a "one" indicates a "read" request.

In addition, the SHT4x features different measurement options for different precision needs and a heater option, as detailed in Table 5 and Section 3.

Command

BIN

HEX

Description

1111 1101

Measure T & RH with highest precision (high repeatability)

1111 0110

Measure T & RH with medium precision (medium repeatability)

1110 0000

Measure T & RH with lowest precision (low repeatability)

1000 1001

Read serial

1001 0100

Soft Reset

0011 1001

Activate highest heater power for 1s

Table 5. Overview of I2C commands for the SHT4x.

For further details on the I2C communication, such as general protocol description, data types and lengths, and checksum calculation, kindly refer to the SHT4x datasheet.
6 Quality and Material Contents

Qualification of the SHTW2 and SHT4x is performed based on the JEDEC JESD47 qualification test method. While both devices are fully RoHS and REACH compliant, the SHT4x is also WEEE compliant.

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7 Further Information
This transition guide aims at providing an overview of the key differences between the SHTW2 and the SHT4x, yet might not be fully inclusive. For further reading on the SHT4x specifications, communication, operation, and application, please consult the dedicated SHTW2 and SHT4x documents provided on the Sensirion webpage www.sensirion.com. In case you are in need of specific details, or would like to request assistance in transitioning from the SHTW2 to the SHT4x or any other Sensirion product, please consult us directly at www.sensirion.com/en/about-us/contact/. Sensors from the SHT4x family will be available for purchase from Q1/2021, while release information and samples will be available in Q4/2020.

8 Revision History

Date August 2020 November 2023

Version 1 1.1

Page(s) all all

Changes Initial version Updated SHT4x information

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Important Notices
Warning, Personal Injury
Do not use this product as safety or emergency stop devices or in any other application where failure of the product could result in personal injury. Do not use this product for applications other than its intended and authorized use. Before installing, handling, using or servicing this product, please consult the data sheet and application notes. Failure to comply with these instructions could result in death or serious injury.
If the Buyer shall purchase or use SENSIRION products for any unintended or unauthorized application, Buyer shall defend, indemnify and hold harmless SENSIRION and its officers, employees, subsidiaries, affiliates and distributors against all claims, costs, damages and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if SENSIRION shall be allegedly negligent with respect to the design or the manufacture of the product.
ESD Precautions
The inherent design of this component causes it to be sensitive to electrostatic discharge (ESD). To prevent ESD-induced damage and/or degradation, take customary and statutory ESD precautions when handling this product. See application note "ESD, Latchup and EMC" for more information.
Warranty
SENSIRION warrants solely to the original purchaser of this product for a period of 12 months (one year) from the date of delivery that this product shall be of the quality, material and workmanship defined in SENSIRION's published specifications of the product. Within such period, if proven to be defective, SENSIRION shall repair and/or replace this product, in SENSIRION's discretion, free of charge to the Buyer, provided that: · notice in writing describing the defects shall be given to SENSIRION within fourteen (14) days after their appearance; · such defects shall be found, to SENSIRION's reasonable satisfaction, to have arisen from SENSIRION's faulty design, material, or
workmanship; · the defective product shall be returned to SENSIRION's factory at the Buyer's expense; and · the warranty period for any repaired or replaced product shall be limited to the unexpired portion of the original period. This warranty does not apply to any equipment which has not been installed and used within the specifications recommended by SENSIRION for the intended and proper use of the equipment. EXCEPT FOR THE WARRANTIES EXPRESSLY SET FORTH HEREIN, SENSIRION MAKES NO WARRANTIES, EITHER EXPRESS OR IMPLIED, WITH RESPECT TO THE PRODUCT. ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE EXPRESSLY EXCLUDED AND DECLINED. SENSIRION is only liable for defects of this product arising under the conditions of operation provided for in the data sheet and proper use of the goods. SENSIRION explicitly disclaims all warranties, express or implied, for any period during which the goods are operated or stored not in accordance with the technical specifications. SENSIRION does not assume any liability arising out of any application or use of any product or circuit and specifically disclaims any and all liability, including without limitation consequential or incidental damages. All operating parameters, including without limitation recommended parameters, must be validated for each customer's applications by customer's technical experts. Recommended parameters can and do vary in different applications. SENSIRION reserves the right, without further notice, (i) to change the product specifications and/or the information in this document and (ii) to improve reliability, functions and design of this product. Copyright © 2021, by SENSIRION. CMOSens® is a trademark of Sensirion. All rights reserved
Headquarters and Subsidiaries

Sensirion AG Laubisruetistr. 50 CH-8712 Staefa ZH Switzerland
phone: +41 44 306 40 00 fax: +41 44 306 40 30 info@sensirion.com www.sensirion.com
Sensirion Taiwan Co. Ltd phone: +886 3 5506701 info@sensirion.com www.sensirion.com
www.sensirion.com

Sensirion Inc., USA phone: +1 312 690 5858 info-us@sensirion.com www.sensirion.com
Sensirion Japan Co. Ltd. phone: +81 3 3444 4940 info-jp@sensirion.com www.sensirion.com/jp

Sensirion Korea Co. Ltd. phone: +82 31 337 7700~3 info-kr@sensirion.com www.sensirion.com/kr
Sensirion China Co. Ltd. phone: +86 755 8252 1501 info-cn@sensirion.com www.sensirion.com/cn

To find your local representative, please visit www.sensirion.com/distributors

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References

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