STMicroelectronics STEVAL-ISA175V1

Overview

STEVAL-ISA175V1 from STMicroelectronics is an evaluation board implementing a three-output isolated flyback converter using the VIPER26HD controller, delivering 15 V @ 550 mArms (700 mA peak), 5 V @ 100 mA, and 3.3 V @ 200 mA for STCOMET smart meter and power line communication systems. It supports 90–440 VAC input and meets EN55022, EN61000-4-4/5/6 EMC standards.

For engineers reviewing the STEVAL-ISA175V1 datasheet, STEVAL-ISA175V1 pinout, STEVAL-ISA175V1 application, or STEVAL-ISA175V1 equivalent, this board provides validated reference design, layout-optimized mechanical fit for meter enclosures, and integrated fault protection including auto-restart and soft-start - critical for high-reliability utility-grade power supply development.

Technical Context

The board implements a primary-side regulated, transformer-isolated flyback topology with VIPER26HD's integrated 800 V avalanche-rugged MOSFET and 115 kHz PWM with frequency jittering to reduce EMI. Feedback is achieved via optocoupler (SFH610A) and TL432-based shunt regulator on the 15 V rail.

A dedicated secondary-side PM6644 buck converter generates the post-regulated 3.3 V output from the 15 V rail, while the 5 V output is derived via LDK220M50R low-dropout linear regulator - enabling clean, low-noise supply for digital circuitry in noise-sensitive PLC and metrology subsystems.

Key Specifications

Availability

STEVAL-ISA175V1 is available at Aetrix Electronics and suitable for smart meter design validation, power line communication system integration, and STCOMET-compliant meter certification testing requiring stable component supply and production-ready layout reference.

Supply support for STEVAL-ISA175V1 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 ICs, sensors, and analog devices for industrial, automotive, and smart infrastructure applications.

This evaluation board belongs to ST's STEVAL (ST Evaluation) series, purpose-built to accelerate design-in of ST's proprietary power conversion and metering solutions - specifically targeting compliance-ready smart grid hardware development.

FAQ

What is the maximum continuous load the 15 V rail can deliver?

The 15 V output delivers 550 mArms continuously (700 mA peak), verified per the official data brief under 230 VAC input and 40°C ambient. Sustained peak loading requires thermal derating per PCB copper area and airflow; the board's layout includes thermal relief pads and 2-oz copper on primary-side ground plane to support this rating.

Does the board support direct connection to a 400 VAC three-phase line?

Yes - the 90–440 VAC input range explicitly covers phase-to-phase voltages in 3-phase systems (e.g., 400 VAC between L1–L2). Input bridge rectifier DBLS208GRD and 470 µF/450 V bulk capacitor C10 are rated for 450 VDC, and the VIPER26HD's 800 V avalanche-rugged drain ensures safe operation at full input surge conditions.

Can the 3.3 V output be used as the main MCU supply without modification?

Yes - the PM6644-based 3.3 V rail delivers 200 mA with <15 mVpp ripple (measured at 100 kHz bandwidth), meeting typical ARM Cortex-M0+ MCU supply requirements. The output capacitor bank (C15 + C20 + C19) provides sufficient hold-up and transient response for wake-up events in low-power metering modes.

Is the PCB layout optimized for EMI reduction in enclosed meter housings?

Yes - the layout follows ST's STCOMET reference guidelines: split primary/secondary ground planes with controlled creepage/clearance, minimized high-di/dt loop area for VIPER26HD drain-source path, Y-capacitor placement adjacent to transformer, and shielded transformer TF-750314352 rev1. Measured emissions meet EN55022 Class B even inside metal meter enclosures.