SHT21 Humidity and Temperature Sensor - Equivalent & Substitute Parts

Part Overview

The SHT21 is a digital humidity and temperature sensor manufactured by Sensirion AG, designed for applications requiring simultaneous measurement of relative humidity and temperature with I2C interface output. The device operates across a wide humidity range of 0 to 100% RH with ±2% RH accuracy and supports supply voltages from 2.1V to 3.6V in a compact 6-TDFN surface mount package.

The SHT21 carries a "Not For New Designs" product status, indicating that Sensirion has discontinued active development and support for this component. This status necessitates identification of functionally equivalent alternatives for new applications and ongoing production requirements where component availability or long-term support is a consideration.

Substiute Parts

SHT21

Sensirion AGIn Stock: 40132SHT21 Datasheet

Current PartRFQ

HPP845E031R4

TE Connectivity Measurement SpecialtiesIn Stock: 1000242HPP845E031R4 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SHT21 is determined by the following critical parameters:

• Sensor Functionality: Both humidity and temperature measurement capability
• Output Interface: I2C digital communication protocol
• Output Resolution: 12-bit data format
• Humidity Accuracy: ±2% RH specification
• Humidity Range: Full 0 to 100% RH coverage
• Operating Temperature Range: -40°C to 125°C minimum
• Supply Voltage Compatibility: Overlap with 2.1V to 3.6V range
• Mounting and Package: Surface mount technology with compatible pinout and footprint

The HPP845E031R4 manufactured by TE Connectivity Measurement Specialties meets all substitution criteria. This component maintains identical humidity and temperature measurement functionality, I2C interface, 12-bit resolution, ±2% RH accuracy, and full 0 to 100% RH range. The operating temperature range and surface mount package are compatible. The supply voltage range of 1.5V to 3.6V provides extended lower-voltage capability compared to the SHT21, ensuring compatibility in all applications where the SHT21 operates.

Parameter Comparison

Engineering Selection Recommendations

The HPP845E031R4 is the qualified substitute for the SHT21 based on the following engineering criteria:

Functional Equivalence: Both components deliver identical humidity and temperature measurement performance with I2C output, 12-bit resolution, and ±2% RH accuracy across the full 0 to 100% RH range.

Compliance and Certification: Both parts maintain ROHS3 compliance, REACH unaffected status, and MSL 1 (unlimited) moisture sensitivity rating, ensuring regulatory and environmental compatibility in equivalent applications.

Product Status Advantage: The HPP845E031R4 carries Active product status, indicating ongoing manufacturer support, continued availability, and long-term design viability. The SHT21's "Not For New Designs" status makes the HPP845E031R4 the appropriate choice for new product development and sustained production.

Enhanced Performance Characteristics: The HPP845E031R4 provides a faster response time of 5 seconds compared to the SHT21's 8 seconds, and extends the lower supply voltage limit to 1.5V, offering improved performance margins in low-power applications.

Package Compatibility: Both components use compatible 6-pin DFN surface mount packages with exposed pads, supporting direct PCB layout adaptation with minimal redesign effort.

Frequently Asked Questions (FAQ)

Q: Can the HPP845E031R4 directly replace the SHT21 without PCB modifications?

A: The HPP845E031R4 uses a 6-VDFN package while the SHT21 uses 6-TDFN. Both are 6-pin DFN variants with 3x3 mm dimensions and compatible pinouts. PCB footprints are functionally equivalent, though minor layout adjustments may be necessary depending on specific pad geometry specifications from each manufacturer's datasheet.

Q: What are the key electrical differences between these sensors?

A: The primary electrical difference is the supply voltage range. The HPP845E031R4 operates from 1.5V to 3.6V, while the SHT21 requires 2.1V to 3.6V. Both maintain identical I2C communication protocol, 12-bit output resolution, and ±2% RH accuracy. The HPP845E031R4 achieves faster response time at 5 seconds versus 8 seconds for the SHT21.

Q: Are there any firmware or software changes required when switching from SHT21 to HPP845E031R4?

A: Both sensors use I2C interface with 12-bit output format and identical humidity/temperature measurement ranges. Software compatibility depends on I2C address configuration and command structure. Consult the HPP845E031R4 datasheet to confirm I2C address and command compatibility with existing SHT21 firmware implementations.

Q: What is the significance of the "Not For New Designs" status on the SHT21?

A: This status indicates that Sensirion has concluded active development and support for the SHT21 product line. Manufacturers typically apply this designation when transitioning to newer alternatives. For new product development, the HPP845E031R4 is recommended to ensure long-term component availability and manufacturer support.

Q: How do the RoHS and REACH compliance statuses compare?

A: Both the SHT21 and HPP845E031R4 are ROHS3 compliant and REACH unaffected, meeting equivalent environmental and regulatory requirements for industrial and commercial applications.

Q: What is the MSL rating and why is it important?

A: Both components carry MSL 1 (Unlimited) rating, indicating unlimited shelf life without moisture bake-out requirements. This simplifies inventory management and reduces handling constraints during manufacturing and assembly processes.