ST Life.augmented


Cold thermostat kit based on AC switches and the STM8S
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The STEVAL-IHT001V2 thermostat kit provides a robust and low-cost ST solution (microcontroller and AC switches) to control refrigerators, freezers or fridge/freezer combinations.

Basic, defrost, and air circulation versions are configurable in order to address the low-end and medium-end cooling appliances market. It allows the control of a single-phase induction motor and a light bulb, and optionally, a defrost resistor and a fan, working on 220/240 VRMS, 50/60 Hz mains voltage. The thermostat kit is operational with 100/120 V RMS 50/60 Hz but the supply capacitor value must be modified.

The board can operate in an ambient temperature range from 0 °C to 60 °C.

The exact maximum temperature depends on the power of the loads. For demonstrative purposes a graphic user interface (GUI) has been developed.

The connection between the PC and STM8S microcontroller, the MCU performing thermostat regulation, is achieved through a USB bus.

As the STM8S is a low-cost MCU without an embedded USB peripheral, an additional MCU (STM32) has been used as a bridge between the PC and STM8S MCU, for demonstrative purposes only.

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Data Brief

Key Features

  • Low-cost solution for spark-free thermostats:
  • No need for a sealed version
  • Low-cost STM8S microcontroller for thermostat control
  • Low-cost capacitive power supply
  • High efficiency:
  • Refrigerator consumption reduction by adjusting and reducing the hysteresis threshold of the temperature
  • Improved efficiency by turning on the defrost resistor only when it's useful and not at each OFF cycle of the compressor (as done in some mechanical thermostats)
  • High system immunity:
  • Overvoltage protected ACS switches: ACST610-8FP for compressor control, ACS110-7SN for defrost resistor and ACS102-6TA for light bulb and fan
  • Class A criteria for IEC 61000-4-4 up to above 3 kV levels
  • Flexibility:
  • Development: program setting with PC interface to change firmware variables
  • Industrialization: end-of-production MCU programming thanks to FLASH, for soft upgrade and efficient MCU stock management
  • RoHS compliant


Design Resources


Technical Documentation

Product Specifications

Description Version Size
DB1651: Cold thermostat kit based on AC switches and the STM8S
3.0 142 KB

User Manual

Description Version Size
UM1542: Cold thermostat kit based on AC switches and the STM8S003F3
1.0 2,942 KB

Hardware Resources

Board Manufacturing Specification

Description Version Size
STEVAL-IHT001V2 gerber files
1.0 287 KB

Bill of Materials

Description Version Size
1.1 51 KB

Schematic Pack

Description Version Size
STEVAL-IHT001V2 schematics
1.1 123 KB

Related Tools and Software

Related Tools and Software

Part Number Description
STSW-IHT001V2 STEVAL-IHT001V2 thermostat setup

License Agreement

Description Version Size
Evaluation products license agreement
1.0 126 KB

Sample & Buy

Part Number Marketing StatusCore ProductOrder From STUnit Price (US$)*
@ 1
Distributor AvailabilityRoHS Compliance GradeDownload
Material Declaration**
STEVAL-IHT001V2ActiveACST610; ACS110; ACS102; STM32F103C6; STM8S103F3-221Distributor reported inventory date: 2016-02-29
Distributor NameRegionStockMin. order
Newark Element14Order NowAMERICA50
Farnell Element14Order NowEUROPE51

(*) 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
(**) 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.