February 2007

Rev 1

1/13

AN2446

Application note

STEVAL-IHT002V1

Intelligent thermostat for compressor based on ST7Ultralite MCU

Introduction

The STEVAL-IHT002V1 is a very low-cost evaluation board designed with the intent to

replace the existing mechanical thermostat.

While driving a compressor, the evaluation board is able to drive the RUN winding, replace

the PTC and drive directly the START winding too. Stall rotor detection is also implemented.

Both functions are oriented to reduce the total power consumption.

The evaluation board is based on the new low-cost, 8-pin, 8-bit ST7Ultralite microcontroller

(MCU), which controls the entire process. The MCU is equipped with a programmable Flash

memory, 1 MHz internal clock source and runs 1 KByte C-based software.

Even if the evaluation board is especially designed for driving small-size or mid-size

compressors, it is fully customizable and adaptable to any other application where

thermostat or temperature control is required.

An STMicroelectronics Patent Application is pending for the compressor control device and

the method for controlling a compressor described in this document.

This document provides a complete description on how to customize the evaluation board.

STEVAL-IHT002V1 evaluation board

www.st.com