Capacitive digital sensor for relative humidity and temperature

The HTS221 is an ultra-compact sensor for relative humidity and temperature. It includes a sensing element and a mixed signal ASIC to provide the measurement information through digital serial interfaces.

The sensing element consists of a polymer dielectric planar capacitor structure capable of detecting relative humidity variations and is manufactured using a dedicated ST process.

The HTS221 is available in a small top-holed cap land grid array (HLGA) package guaranteed to operate over a temperature range from -40 °C to +120 °C.

Key Features

  • 0 to 100% relative humidity range
  • Supply voltage: 1.7 to 3.6 V
  • Low power consumption: 2 μA @ 1 Hz ODR
  • Selectable ODR from 1 Hz to 12.5 Hz
  • High rH sensitivity: 0.004% rH/LSB
  • Humidity accuracy: ± 3.5% rH, 20 to +80% rH
  • Temperature accuracy: ± 0.5 °C,15 to +40 °C
  • Embedded 16-bit ADC
  • 16-bit humidity and temperature output data
  • SPI and I²C interfaces
  • Factory calibrated
  • Tiny 2 x 2 x 0.9 mm package
  • ECOPACK® compliant


Technical Documentation

Product Specifications
Description Version Size
DS10329 DS10329: Capacitive digital sensor for relative humidity and temperature 4.0 742 KB
Application Notes
Description Version Size
AN4503 AN4503: Environmental sensors: Hardware abstraction layer for Android 3.0 241 KB
AN4722 AN4722: HTS221 digital humidity sensor: hardware guidelines for system integration 1.0 844 KB
Technical Notes & Articles
Description Version Size
TN1219 TN1219: HTS221 digital humidity sensor: reference design implementation 2.0 367 KB
TN1218 TN1218: Interpreting humidity and temperature readings in the HTS221 digital humidity sensor 2.0 1 MB
TN1198 TN1198: Surface mount guidelines for MEMS sensors in HLGA packages 1.0 128 KB

Tools and Software

STM32 Open Development Environment
Embedded Software
MCUs Embedded Software
MEMS and Sensors Software
Evaluation Tools
Product Evaluation Tools
Solution Evaluation Tools
Support & Community

Sample & Buy

Part Number Marketing Status Quantity Unit Price (US$) * Package Packing Type Operating Temperature (°C) (min) Operating Temperature (°C) (max) ECCN (EU) ECCN (US) Country of Origin More info Order from ST Order from Distributors
HTS221TR Active 1000 1.4 HLGA-6L 2X2X0.9 Tape And Reel -40 120 NEC EAR99 - MORE INFO Get Sample Add to cart DISTRIBUTOR AVAILABILITY

(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office  or our Distributors

Quality & Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
HTS221TR ActiveHLGA-6L 2X2X0.9IndustrialEcopack2 0 0

(**) The Material Declaration forms available on may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.