SENSIRION SHT4x Digital Humidity and Temperature Sensor User Guide

SENSIRION SHT4x Digital Humidity and Temperature Sensor

Product Information

Specifications

• Models: SHT3x, SHT4x
• Improved accuracy, power consumption, and robustness
• Powerful internal heater for self-decontamination
• Superior versatility and technology from two decades of sensor
  development

Product Usage Instructions

1. General
   This document provides guidelines for replacing SHT3x with sensors from the SHT4x family and highlights important design differences.

Performance Comparison

1. Relative Humidity and Temperature
   Comparison of Relative Humidity and Temperature parameters between SHT3x and SHT4x:

   • Relative humidity RH accuracy
   • Repeatability
   • Resolution
   • Hysteresis
   • Response time
   • Long-term drift
   • Condensation behavior
   • Temperature accuracy, repeatability, resolution, specified range, response time, long-term drift

2. Flagship SHT4x Feature: Built-In Heater
   The SHT4x features a built-in heater for plausibility checks and improved performance.

3. Package Design Differences
   Differences in the package design between SHT3x and SHT4x models are outlined for consideration during installation.

4. Communication Compatibility
   SHT3x has 8 pins I2C with 2 addresses, while SHT4x has 4 pins I2C with multiple addresses for communication compatibility.

5. Quality and Material Contents
   The sensors in the SHT4x family offer high quality and are made from durable materials to ensure reliability and longevity.

6.  Further Information
   For more details on the SHT4x sensors, visit www.sensirion.com for additional resources and support.

FAQ

• Q: What is the main difference between SHT3x and SHT4x?
  A: The main differences include improved accuracy, lower power consumption, and the addition of a powerful internal heater in the SHT4x model for self- decontamination.

SHT3x – SHT4x Transition Guide
Boarding the new flagship RH/T sensor generation SHT3x

• Improved accuracy, power consumption, and robustness
• Powerful internal heater for self-decontamination
• Superior versatility and technology from two decades of sensor development

Abstract

• Introduced as a highly versatile digital humidity (RH) and temperature (T) sensor platform, the SHT3x family already enables outstanding sensing performance for several years. Sensirion now proudly features its all newflagship sensors from the SHT4x family, which profit 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 SHT3x applications. In particular, the SHT4x outperforms the SHT3x in every aspect and offers versatile add-ons, such as a powerful heater for selfdecontamination, conformal coating protection, or filter membranes

Important changes

with D T ³60°C, Full condensation robustness

General
This document aims to provide a high-level guideline to replace SHT3x with sensors from the SHT4x family and outlines important differences to be considered in design-in processes.

Performance Comparison

Relative Humidity and Temperature

Relative humidity
RH accuracy2| Typ.| ± 2| ± 1.0 … 1.8| %RH
Repeatability3| –| 0.08/0.15/0.21| 0.08/0.15/0.25| %RH
Resolution4| –| 0.01| 0.01| %RH
Hysteresis| –| ±0.8| ±1| %RH
Specified range5| extended6| 0 – 100| 0 – 100| %RH
Response time7| t 63%| 8| 4| s
Long-term drift8| Typ.| <0.25| <0.25| %RH/y
Condensation behavior| Droplet formation| Slight signal drop| No signal drop| –
Temperature
T Accuracy1| Typ.| ± 0.2| ± 0.1| °C
Repeatability2| –| 0.04/0.08/0.15| 0.04/0.07/0.1| °C
Resolution3| –| 0.01| 0.01| °C
Specified range4| –| −40 – +125| −40 – +125| °C
Response time9| t 63%| > 2| 2| s
Long-term drift10| Typ.| < 0.03| < 0.03| °C/y

Table

1. Humidity and temperature specifications of the SHT3x and SHT4x, where bold values highlight important differences. For further details, kindly refer to the SHT3x 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 (3σ) 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.

 Electrical Characteristics

Parameter| Symbol| Conditions| SHT3x| SHT4x| Units
---|---|---|---|---|---
Min| Typ.| Max| Min| Typ.| Max
Supply voltage| V DD| | 2.15| 3.3| 5.5| 1.08| 3.3| 3.6| V
Power-up/down level| V POR| Static power supply| 1.8| 2.1| 2.15| 0.6| –| 1.08| V

Supply current (heater not activated)11

| ****

I DD

| Idle state| –| 0.2| 2.0| –| 0.08| –| µA
Measurement| –| 600| 1500| –| 320| –| µA
Average| –| 1.7| | –| 0.4 (low)

2.2 (high)

| –| µA
Power consumption12| –| Average| –| 5.6| | –| 0.5 (low)

2.6 (high)

| –| µW
Low level input voltage| V IL| –| 0| –| 0.3 V DD| 0| –| 0.3 V DD| V
High level input voltage| V IH| –| 0.7 V DD| –| V DD| 0.7 V DD| –| V DD| V
Application circuit design| –| –| Similar, for details see SHT3x or SHT4x datasheet| –

Table 2. Key electrical specifications of the SHT3x and SHT4x, where bold values highlight important differences. For further details, kindly refer to the SHT3x and SHT4x datasheets.

Timing Specifications

Parameter| Symbol| Conditions| SHT3x| SHT4x| Units
---|---|---|---|---|---
Min| Typ.| Max| Min| Typ.| Max
Power-up time| t PU| After hard reset,

V DD ≥ V POR

| –| 0.5| 1| –| –| 1| ms
Soft reset time| t SR| After soft reset| –| 0.5| 1| –| –| 1| ms
Measurement duration| t Meas| Medium repeatability| –| 4.5| 6| –| 3.7| 4.5| ms
Heater-on duration| t Heater| | –| –| –| 0.1| –| 1| s

Table 3. Key timing specifications of the SHT3x and SHT4x, where bold values highlight important differences. For further details, kindly refer to the SHT3x and SHT4x datasheets.

 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 0.1 or 1 second. After the heater on-time, 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.

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 comparison to the SHT3x, the package is considerably smaller, enabling power efficient, accurate, and robust RH/T sensing with fast reaction times. Instead of featuring eight pins, the bottom side of the SHT4x DFN package exposes four metallic contacts, which are Ni/Pd/Au coated.

Table 4. Key package differences between the SHT3x and SHT4x. For further details, kindly refer to the SHT3x and SHT4x datasheets.

Figure 1. Dimensional drawing of the SHT3x including (units mm).

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

 Communication Compatibility

Both chips feature the I2C communication protocol 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|

Description

---|---
BIN| HEX
1111 1101| FD| Measure T & RH with highest precision (high repeatability)
1111 0110| F6| Measure T & RH with medium precision (medium repeatability)
1110 0000| E0| Measure T & RH with lowest precision (low repeatability)
1000 1001| 89| Read serial
1001 0100| 94| Soft Reset
0011 1001| 39| 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.

Quality and Material Contents

Qualification of the SHT3x 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.

Further Information

This transition guide aims at providing an overview of the key differences between the SHT3x and the SHT4x, yet might not be fully inclusive. For further reading on the SHT4x specifications, communication, operation, and application, please consult the dedicated SHT3x 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 SHT3x to the SHT4x or any other Sensirion product, please consult us directly at www.sensirion.com/en/about- us/contact/.

Revision History

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
• 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
www.sensirion.com

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