SHT71 Humidity and Temperature Sensor - Equivalent & Substitute Parts

Part Overview

The SHT71 is a digital humidity and temperature sensor module manufactured by Sensirion AG, designed for applications requiring simultaneous measurement of relative humidity (0–100% RH) and temperature across an extended operating range (-40°C to 125°C). The sensor delivers 12-bit digital output with ±3% RH accuracy and an 8-second response time, operating from a 2.4V to 5.5V supply. The device is packaged in a 4-SIP through-hole module format.

The SHT71 has reached obsolete product status. Identifying equivalent substitute components is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or maintenance requirements for systems currently utilizing this sensor.

Substiute Parts

SHT71

Sensirion AGIn Stock: 2158SHT71 Datasheet

Current PartRFQ

SHT31-DIS-B2.5KS

SensirionIn Stock: 5350SHT31-DIS-B2.5KS Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SHT71 is determined by the following critical parameters:

• Sensor Functionality: Both humidity and temperature measurement capability required
• Humidity Measurement Range: Full 0–100% RH coverage
• Operating Temperature Range: -40°C to 125°C compatibility
• Supply Voltage Compatibility: Overlap within 2.4V–5.5V range
• Response Time: 8-second response time maintained
• Regulatory Compliance: ROHS3 and REACH compliance status

The SHT31-DIS-B2.5KS qualifies as a manufacturer-recommended substitute. While it introduces design changes in mounting technology (surface mount versus through hole), communication protocol (I2C versus direct digital), and output resolution (16-bit versus 12-bit), it maintains functional equivalence across humidity range, temperature operating window, response time, and regulatory compliance. The improved accuracy specification (±2% RH versus ±3% RH) and extended supply voltage floor (2.15V versus 2.4V) represent performance enhancements.

Parameter Comparison

Engineering Selection Recommendations

The SHT31-DIS-B2.5KS is the manufacturer-recommended substitute for the obsolete SHT71. Both devices maintain ROHS3 compliance and REACH unaffected status, satisfying regulatory requirements for new designs and production continuity.

Selection of the SHT31-DIS-B2.5KS requires evaluation of design-level changes:

• Mounting Architecture: Transition from through-hole to surface-mount technology necessitates PCB layout modification and assembly process adjustment.
• Communication Protocol: Shift from direct digital output to I2C serial interface requires firmware or microcontroller interface redesign.
• Package Footprint: Change from 4-SIP to 8-VFDFN (2.5×2.5 mm) impacts board space allocation and thermal management considerations.

The substitute part delivers improved measurement accuracy (±2% RH) and lower minimum supply voltage (2.15V), representing functional enhancements over the original design.

Frequently Asked Questions (FAQ)

Q: Can the SHT31-DIS-B2.5KS directly replace the SHT71 without circuit modification?

A: No. The SHT31-DIS-B2.5KS requires circuit redesign due to differences in mounting type (surface mount versus through hole), communication protocol (I2C versus direct digital output), and package footprint. PCB layout, assembly process, and microcontroller interface firmware must be updated.

Q: Are the humidity and temperature measurement ranges identical between the two sensors?

A: Yes. Both sensors measure humidity across 0–100% RH and operate across -40°C to 125°C. Response time is identical at 8 seconds for both devices.

Q: What is the significance of the output resolution difference (12-bit versus 16-bit)?

A: The SHT31-DIS-B2.5KS provides 16-bit resolution compared to the SHT71's 12-bit resolution. This delivers finer measurement granularity and supports the improved ±2% RH accuracy specification. Existing firmware must accommodate the increased data word length.

Q: Do both sensors meet the same regulatory compliance standards?

A: Yes. Both the SHT71 and SHT31-DIS-B2.5KS are ROHS3 compliant and REACH unaffected, satisfying equivalent regulatory requirements.

Q: What are the supply voltage considerations for substitution?

A: The SHT71 operates from 2.4V to 5.5V, while the SHT31-DIS-B2.5KS operates from 2.15V to 5.5V. The substitute part accepts a lower minimum voltage, providing expanded supply compatibility. Both devices function across the standard 5V logic supply range.

Q: How does the I2C interface of the SHT31-DIS-B2.5KS differ from the SHT71's direct digital output?

A: The SHT71 provides direct digital output requiring parallel data lines and control signals. The SHT31-DIS-B2.5KS uses I2C serial communication, reducing pin count and simplifying board routing but requiring I2C protocol implementation in the host microcontroller.