STMicroelectronics STEVAL-IHT008V1

Overview

STEVAL-IHT008V1 from STMicroelectronics is an evaluation board demonstrating a low-standby-loss front-end with inrush current limitation and insulated AC switch control for residential appliance power stages. It implements soft-start via phase-controlled T1635T-8FP Triac, achieves <0.3 W standby loss via full DC bus disconnection, and complies with IEC 61000-3-3, EN 55015, and IEC 61000-4-4/5 immunity criteria.

For engineers reviewing the STEVAL-IHT008V1 datasheet, STEVAL-IHT008V1 pinout, STEVAL-IHT008V1 application, or STEVAL-IHT008V1 equivalent, this board provides validated reference design for IEC-compliant inrush management, isolated AC load switching, and integrated PFC-compatible front-end architecture using STM8S103K3 MCU and snubberless Triacs.

Technical Context

The board integrates a 16 A snubberless Triac (T1635T-8FP) in series with the AC mains to enable progressive phase-control soft-start under STM8S103K3 firmware control, eliminating NTC-based inrush solutions. Standby DC bus disconnection is achieved by fully turning off the series Triac-no relay required-reducing losses below 0.3 W.

It supports both continuous and discontinuous conduction mode PFC operation and delivers isolated gate drive for multiple overvoltage-protected AC switches (ACS108-8SN, ACST210-8FP, Z0109MUF) using opto-transistors powered from a shared flyback SMPS (15 V_DC/5 V_DC/V_{CC_AC}).

Key Specifications

Availability

STEVAL-IHT008V1 is available at Aetrix Electronics and suitable for residential appliance front-end design, IEC 61000-3-3 compliance validation, and isolated AC load switching development requiring stable component supply and reference-grade implementation fidelity.

Supply support for STEVAL-IHT008V1 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 evaluation platform family, engineered to accelerate adoption of energy-efficient, standards-compliant power architectures for white goods and smart home appliances.

FAQ

What is the primary function of the T1635T-8FP Triac on this board?

The T1635T-8FP serves as the main inrush current limiter by inserting controlled phase-angle conduction between AC mains and the rectifier bridge. Under STM8S103K3 firmware control, it ramps up conduction over multiple half-cycles to limit peak inrush while avoiding NTC resistors and bypass relays.

Does the board support PFC integration, and how is it implemented?

Yes-it supports both continuous and discontinuous conduction mode PFC stages upstream of the rectifier input. The design isolates PFC operation from the inrush control circuitry, allowing independent optimization while maintaining IEC 61000-3-3 compliance through Triac-based soft-start.

How is AC load isolation achieved for the output switches?

Isolation is provided via opto-transistors (IS127) driven from the board's internal 15 V_DC rail. These opto-couplers deliver gate signals to ACS108-8SN, ACST210-8FP, and Z0109MUF AC switches without requiring separate isolated supplies-enabling compact, cost-effective residential appliance control.

What firmware is used, and where is it hosted?

The board runs STSW-IHT008 firmware on the onboard STM8S103K3 MCU. This firmware implements real-time phase-control algorithms, ZVS detection, inrush current monitoring, and coordinated switching logic for all five AC outputs. Source code and binaries are provided by ST in the official STSW-IHT008 package.