STMicroelectronics STEVAL-ISA179V1

Overview

STEVAL-ISA179V1 from STMicroelectronics is an evaluation board implementing a universal-input (85–265 VAC), 15 V / 0.15 A, 2.25 W buck converter using the VIPer0P off-line high-voltage converter IC. It features zero-power standby (<40 mW @230 VAC), >77% active-mode efficiency, EN55022 Class-B EMI compliance, and a single-layer PCB with minimal BOM for cost-sensitive auxiliary power supply applications.

For engineers reviewing the STEVAL-ISA179V1 datasheet, STEVAL-ISA179V1 schematic, STEVAL-ISA179V1 application, or STEVAL-ISA179V1 equivalent, this board enables rapid validation of VIPer0P-based offline buck topologies in low-power AC/DC conversion, especially where compact size, ultra-low standby consumption, and regulatory-compliant EMI performance are required.

Technical Context

The board implements a non-isolated buck converter topology powered directly from rectified AC mains, leveraging the VIPer0P's integrated 800 V MOSFET and current-mode PWM controller. It operates without an optocoupler or secondary-side feedback, relying on primary-side regulation via auxiliary winding sensing.

Key design constraints include fixed 15 V output, no load regulation adjustment, and operation limited to discontinuous conduction mode (DCM) due to the VIPer0P's internal control architecture and the selected 1 mH input inductor. The board omits optional components (C5, C6) to simplify evaluation and reduce cost.

Key Specifications

Availability

STEVAL-ISA179V1 is available at Aetrix Electronics and suitable for industrial control auxiliary supplies, smart meter power rails, IoT sensor node AC/DC conversion, and white goods sub-power systems requiring stable component supply and fast prototyping support.

Supply support for STEVAL-ISA179V1 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, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.

This board belongs to ST's STEVAL (ST Evaluation) series-engineered to accelerate design-in of ST's power converters by providing fully tested, documented, and compliant reference implementations for VIPer™ Plus offline controllers.

FAQ

Is STEVAL-ISA179V1 isolated or non-isolated?

STEVAL-ISA179V1 implements a non-isolated buck converter. Its output shares ground with the rectified AC input, making it unsuitable for applications requiring galvanic isolation or user-accessible outputs. Safety-critical designs must incorporate external isolation or use an isolated topology.

Can the output voltage be adjusted?

No. The output is fixed at 15 V by the transformer turns ratio and feedback network (R3, R4). There is no onboard provision for voltage adjustment; changing output requires redesigning the auxiliary winding and feedback resistor values per VIPer0P's primary-sensing regulation method.

What is the role of the VIPer0P IC on this board?

The VIPer0P serves as the integrated high-voltage controller + 800 V MOSFET, enabling direct connection to rectified mains. It provides current-mode PWM control, built-in protection (overcurrent, overtemperature, overvoltage), and zero-power startup-eliminating the need for external bias winding or startup resistors.

Does this board support synchronous rectification?

No. The output stage uses a standard silicon diode (STTH1L06) for rectification. The VIPer0P does not support external synchronous rectifier control signals, and the board layout lacks gate drive circuitry or footprint for a MOSFET replacement.