STMicroelectronics STEVAL-ISA191V1

Overview

STEVAL-ISA191V1 from STMicroelectronics is an evaluation board implementing a 15 W isolated dual-output flyback converter using the VIPer37LE high-voltage PWM controller, delivering 5 V / 1.2 A and 12 V / 0.75 A from universal AC input (85–265 VAC, 50–60 Hz), with <40 mW no-load consumption and >75% average efficiency.

For engineers reviewing the STEVAL-ISA191V1 datasheet, STEVAL-ISA191V1 schematic, STEVAL-ISA191V1 application, or STEVAL-ISA191V1 equivalent, this board serves as a validated reference design for compact, low-standby-power AC/DC power supplies targeting industrial control interfaces, IoT edge node power rails, and dual-rail embedded systems requiring EMI-compliant Class-B operation.

Technical Context

The board implements a primary-side regulated, transformer-isolated flyback topology with fixed 60 kHz switching frequency and frequency jittering to reduce EMI peaks. It uses burst-mode operation under light/no load to achieve <40 mW standby consumption at 230 VAC.

VIPer37LE integrates an 800 V avalanche-rated MOSFET and current-mode PWM controller with comprehensive protection: overvoltage, overload, output short-circuit, secondary winding short, hard saturation, and brown-out detection - enabling robust single-chip AC/DC conversion without optocoupler feedback compensation.

Key Specifications

Availability

STEVAL-ISA191V1 is available at Aetrix Electronics and suitable for industrial control interfaces, IoT edge node power rails, and dual-rail embedded systems requiring stable component supply, rapid prototyping validation, and EMI-compliant AC/DC conversion.

Supply support for STEVAL-ISA191V1 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 designing and manufacturing microcontrollers, power ICs, sensors, and analog/mixed-signal devices for automotive, industrial, and consumer applications.

This board belongs to ST's STEVAL evaluation platform family, engineered to accelerate development of certified, production-ready AC/DC power supplies using VIPerPlus off-line converters in cost-sensitive, space-constrained designs.

FAQ

What is the purpose of the STEVAL-ISA191V1 evaluation board?

The STEVAL-ISA191V1 is a fully assembled, tested reference design for a 15 W dual-output isolated flyback converter. It demonstrates the VIPer37LE's capability to deliver tightly regulated 5 V and 12 V outputs from universal AC input with minimal external components, low standby power, and Class-B EMI compliance - intended for rapid power architecture validation and schematic review.

Does this board require an optocoupler for feedback regulation?

No. The STEVAL-ISA191V1 uses primary-side regulation via the VIPer37LE's internal sensing and control loop, eliminating the need for an optocoupler or secondary-side TL431 shunt regulator. Feedback is derived from auxiliary winding voltage and internal reference, simplifying layout and improving long-term reliability.

Can the output voltages be adjusted without hardware modification?

No. Output voltages are fixed by transformer turns ratio and feedback resistor network (R13/R14 for 5 V; R16/R17 for 12 V). Adjusting either output requires changing those resistors and verifying regulation stability and cross-regulation performance - not supported out-of-box.

What safety certifications does this board support?

The board meets EN55022 Class B conducted and radiated EMI limits and incorporates reinforced isolation per IEC 60747-5-2 (creepage/clearance ≥8 mm between primary and secondary). It is not pre-certified to UL/IEC 62368-1, but its layout and component selection align with requirements for end-equipment certification when integrated into properly designed enclosures.