STMicroelectronics STEVAL-ISA071V2

Overview

STEVAL-ISA071V2 from STMicroelectronics is a non-isolated switched-mode power supply (SMPS) demonstration board based on the VIPER16 high-voltage converter IC, delivering +12 VDC ±10% (referred to –5 V) at 160 mA and –5 VDC ±4% at 400 mA across 85–264 V_RMS AC input (45–66 Hz), with 4 W maximum output power and 70 mW standby consumption at 230 VAC.

For engineers reviewing the STEVAL-ISA071V2 datasheet, STEVAL-ISA071V2 schematic, STEVAL-ISA071V2 application, or STEVAL-ISA071V2 equivalent, this board supports rapid evaluation of VIPER16-based dual-rail, neutral-referenced SMPS designs for industrial control interfaces, triac-driven loads, relay drivers, and op-amp biasing in mains-connected embedded systems.

Technical Context

The board implements a flyback-derived, non-isolated buck-derived topology using the VIPER16's integrated 800 V avalanche-rated power MOSFET and current-mode PWM controller. It operates without an optocoupler or transformer secondary winding, referencing both outputs to neutral (N), enabling direct triac gate drive and low-component-count AC/DC conversion.

Output regulation relies on primary-side sensing via auxiliary winding feedback and internal reference trimming. The –5 V rail is generated first and serves as the reference ground for the +12 V output, supporting simultaneous dual-polarity supply generation from a single-stage converter with EN55022 Class B EMI compliance.

Key Specifications

Availability

STEVAL-ISA071V2 is available at Aetrix Electronics and suitable for industrial control interfaces, triac-based AC load switching, relay driver circuits, and op-amp biasing in mains-connected embedded systems requiring stable component supply and documented reference design validation.

Supply support for STEVAL-ISA071V2 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 specializing in power management, microcontrollers, sensors, and analog ICs, with manufacturing and R&D operations across Europe, Asia, and the Americas.

This board belongs to ST's STEVAL (ST Evaluation) series-designed to accelerate prototyping and validation of ST's proprietary power ICs like VIPER16 in real-world AC/DC conversion applications with minimal external components.

FAQ

Is STEVAL-ISA071V2 isolated from AC mains?

No. The board is explicitly non-isolated: AC neutral (N) is directly connected to the output common reference, making both +12 V and –5 V rails referenced to neutral. This configuration eliminates transformer isolation but requires strict adherence to safety standards limiting user-accessible circuitry and mandating enclosure grounding per IEC 61000-4-5 and local wiring codes.

Can the +12 V and –5 V outputs be used simultaneously?

Yes. The design delivers both rails concurrently: –5 V at up to 400 mA serves as the reference ground for the +12 V rail, which provides up to 160 mA. Total combined output power remains within the 4 W limit (6 W at 230 V), and cross-regulation is maintained via primary-side feedback without secondary-side compensation components.

What is the role of the VIPER16 IC on this board?

The VIPER16 integrates an 800 V avalanche-rated power MOSFET, current-mode PWM controller, startup circuit, and protection features (overcurrent, overtemperature, and auto-restart). It enables single-chip AC/DC conversion with minimal external parts-eliminating separate gate drivers, controllers, and high-voltage FETs while supporting direct neutral-referenced output topologies.

Does STEVAL-ISA071V2 support EN55022 Class B EMI limits out-of-the-box?

Yes. The board meets EN55022 Class B conducted and radiated emission limits without additional filtering, verified per the original ST documentation (Doc ID 17294 Rev 2). Layout, snubber component values, and Y-cap placement are optimized for compliance, making it suitable for residential and office equipment deployments.