Cold thermostat kit based on AC switches and the STM8S

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.

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





Description Version Size
DB1651 DB1651: Cold thermostat kit based on AC switches and the STM8S 3.0 142 KB
Description Version Size
UM1542 UM1542: Cold thermostat kit based on AC switches and the STM8S003F3 1.0 2 MB


Board Manufacturing Specifications
Description Version Size
STEVAL-IHT001V2 gerber files 1.0 286 KB
Bill of Materials
Description Version Size
Schematic Pack
Description Version Size
STEVAL-IHT001V2 schematics 1.1 122 KB


Description Version Size
Evaluation products license agreement 1.4 128 KB


Evaluation Tool Software
Related Applications


型号 Core Product Marketing Status Unit Price (US$) * Quantity ECCN (EU) ECCN (US) Country of Origin More info Order from ST Order from Distributors
STEVAL-IHT001V2 ACST610; ACS110; ACS102; STM32F103C6; STM8S103F3 Active 208.25 1 NEC 3A991A2 ITALY MORE INFO 直接购买 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


型号 Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
STEVAL-IHT001V2 ActiveCARDIndustrialEcopack2

(**) 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.