STMicroelectronics STEVAL-IHT003V2

Overview

STEVAL-IHT003V2 from STMicroelectronics is a low-loss e-starter evaluation board for refrigerator and freezer compressor starter circuits, built around the ACST610-8T AC switch and retaining the PTC thermistor for safety compliance with EN60335-1. It reduces standby power loss from 2.5 W to 380 mW at 230 VAC and to 40 mW at 100 VAC, enabling energy-efficient compressor start-up without compromising fault protection.

For engineers reviewing the STEVAL-IHT003V2 datasheet, STEVAL-IHT003V2 application, STEVAL-IHT003V2 schematic, or STEVAL-IHT003V2 alternative boards, this evaluation platform provides validated design implementation, PTC behavior verification guidance, R4 resistor tuning methodology, and direct reference for IEC/EN60335-1-compliant AC motor starter optimization in white goods.

Technical Context

The board implements a patented ST solution that actively disables PTC current flow after motor run-up using the ACST610-8T triac-based AC switch, while preserving the PTC as a passive safety element against short-circuit or diode-mode failure of the AC switch. The control logic relies on Q1 (PMBT2907A) and Q2 (PMBT2222A) transistors monitoring PTC voltage thresholds (VPTC1/VPTC2) to trigger turn-off.

Design includes dual-stage timing via C1/R3 and C2/R7 networks, T2 (X0202NN) snubberless triac driver, D1 (1N4007) rectifier, and DF06 bridge rectifier. R4 (30 kΩ default) is user-adjustable to match specific PTC characteristics - critical for reliable VPTC1/VPTC2 detection across compressor models.

Key Specifications

Availability

STEVAL-IHT003V2 is available at Aetrix Electronics and suitable for refrigerator compressor design validation, freezer control system prototyping, and EN60335-1-compliant white goods development requiring stable component supply and reference-grade starter circuit implementation.

Supply support for STEVAL-IHT003V2 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for industrial, automotive, and consumer applications.

This board belongs to ST's STEVAL (ST Evaluation) series, engineered specifically to accelerate adoption of proprietary energy-saving topologies - here, reducing PTC losses in compressor starters while maintaining functional safety.

FAQ

Is STEVAL-IHT003V2 a production-ready module or an evaluation-only board?

STEVAL-IHT003V2 is strictly an evaluation board - not certified for end-product integration. It provides a fully assembled, tested reference design to validate the low-loss e-starter concept, verify PTC behavior, and tune R4 for specific compressors. No safety or EMC certifications are granted for standalone use in final appliances.

Why does the board retain the PTC resistor if the ACST610-8T switches it off?

The PTC remains physically in-circuit to satisfy EN60335-1 Clause 19.10.2, which mandates inherent protection against hazardous temperature rise during AC switch failure modes (e.g., short-circuit or diode-mode conduction). Its presence ensures thermal cutoff capability even if the ACST610-8T fails closed.

What is the role of R4, and how do I select its value?

R4 sets the voltage divider ratio determining VPTC1/VPTC2 detection thresholds for Q1/Q2 switching. Its value must be adjusted based on measured PTC cold/hot resistance and applied voltage - typical range is 10 kΩ to 100 kΩ. The board includes test points J17 and J18 to monitor these voltages during compressor run-up.

Can STEVAL-IHT003V2 be used with inverter-driven compressors?

No - this board targets single-phase induction compressors with PTC-based start circuits only. It is incompatible with inverter-fed motors, which use electronic commutation and lack PTC elements. The timing and voltage detection logic assumes fixed-line-frequency PTC thermal response, not variable-frequency drive conditions.