STMicroelectronics STEVAL-ISA177V1

Overview

STEVAL-ISA177V1 from STMicroelectronics is an evaluation board implementing a non-isolated flyback converter using the VIPer01 offline high-voltage controller IC, delivering 5 V at 0.85 A (4.25 W) from universal AC input (85–265 VAC). It features single-layer PCB layout, <9 mW standby power at 230 VAC, >74% active-mode efficiency, and EN55022 Class-B EMI compliance for low-noise embedded power supply design.

For engineers reviewing the STEVAL-ISA177V1 datasheet, STEVAL-ISA177V1 schematic, STEVAL-ISA177V1 application notes, or STEVAL-ISA177V1 BOM, this board serves as a validated reference for compact, low-standby AC-DC flyback designs targeting cost-sensitive industrial and consumer auxiliary power rails.

Technical Context

The board implements a primary-side regulated, current-mode controlled flyback topology with no optocoupler or secondary-side feedback, relying on VIPer01's integrated 800 V MOSFET and proprietary zero-power startup circuitry. Regulation is achieved via auxiliary winding sensing and internal compensation.

VIPer01 integrates startup current source, PWM controller, protection logic (overcurrent, overtemperature, brownout), and 800 V avalanche-rugged power switch in SO-16 package - enabling direct rectified AC connection without external HV startup resistor.

Key Specifications

Availability

STEVAL-ISA177V1 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 standby power systems requiring stable component supply and rapid prototyping validation.

Supply support for STEVAL-ISA177V1 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 analog, MCU, power, and sensor solutions for automotive, industrial, and consumer markets.

This board belongs to ST's STEVAL (ST Evaluation) series - purpose-built reference designs that demonstrate real-world implementation of ST's power ICs, accelerating development of certified, production-ready power stages.

FAQ

Is STEVAL-ISA177V1 suitable for isolated power supply designs?

No. The board implements a non-isolated flyback topology with shared ground between input and output. It lacks reinforced insulation, creepage/clearance for safety isolation, and Y-capacitor filtering. For isolated applications, ST recommends STEVAL-ISA147V1 or similar optocoupler-feedback designs.

Can the output voltage be adjusted to 3.3 V or 12 V?

Not directly. Output is fixed at 5 V by transformer turns ratio and VIPer01's internal regulation threshold. To achieve 3.3 V or 12 V, the transformer must be rewound or replaced, and feedback network recalculated - requiring revalidation of stability, efficiency, and EMI.

Does STEVAL-ISA177V1 include overvoltage or short-circuit protection?

Yes. VIPer01 provides cycle-by-cycle current limiting, thermal shutdown, and auto-restart after overtemperature or output short. However, it does not include output overvoltage protection (OVP) beyond inherent clamp behavior - external Zener clamping is recommended for critical loads.

What is the minimum required input capacitance for reliable operation?

The board uses a 2.2 µF/400 V bulk capacitor. For stable operation across 85–265 VAC, ST specifies ≥1.5 µF rated ≥400 V. Reducing below 1.2 µF risks startup failure at low line and increased ripple-induced regulation error.