STMicroelectronics STEVAL-ISA134V1

Overview

STEVAL-ISA134V1 from STMicroelectronics is a 12 V, 4 W isolated flyback demonstration board based on the VIPer06 high-voltage PWM controller IC, operating at 115 kHz with frequency jittering for EMI reduction, supporting universal AC input (85–265 VAC), and delivering ±5% low-frequency output regulation with 50 mV high-frequency ripple.

For engineers reviewing the STEVAL-ISA134V1 datasheet, STEVAL-ISA134V1 pinout, STEVAL-ISA134V1 application, or STEVAL-ISA134V1 equivalent, this board serves as a validated reference design for compact, cost-sensitive auxiliary power supplies requiring safety isolation, cycle-by-cycle current limiting, thermal shutdown, and auto-restart after fault conditions.

Technical Context

The board implements an isolated flyback topology using the VIPer06 - an integrated 800 V avalanche-rugged off-line converter with internal high-voltage startup, fixed 115 kHz switching frequency, and built-in soft-start. It uses an auxiliary winding to enable open-loop failure protection and supports adjustable current limit via external resistor.

Input rectification employs a bridge rectifier feeding into a bulk capacitor; output regulation relies on optocoupler feedback to the VIPer06's COMP pin, enabling primary-side sensing without secondary-side TL431. The design achieves ≥71% average efficiency at full load and operates up to 60 °C ambient temperature.

Key Specifications

Availability

STEVAL-ISA134V1 is available at Aetrix Electronics and suitable for external AC/DC adapters, auxiliary power supplies in consumer audio/video equipment, and low-power industrial control modules requiring stable component supply and rapid prototyping validation.

Supply support for STEVAL-ISA134V1 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, Switzerland, designing and manufacturing microcontrollers, power ICs, sensors, and analog components for industrial, automotive, and consumer markets.

This evaluation board belongs to ST's STEVAL (ST Evaluation) series - purpose-built reference platforms that demonstrate real-world implementation of ST's power converters, emphasizing ease of evaluation, safety compliance, and design reuse in cost-sensitive applications.

FAQ

What is the primary function of the STEVAL-ISA134V1 board?

The STEVAL-ISA134V1 is a fully assembled, tested demonstration board implementing a 12 V, 4 W isolated flyback power supply. Its core function is to validate the VIPer06 controller's performance in a production-ready topology, including EMI-optimized switching, precise output regulation, and comprehensive protection features such as thermal shutdown and auto-restart after fault.

Does the board include safety isolation and certification support?

Yes - the design incorporates reinforced isolation between primary and secondary sides per IEC 60950-1 requirements, using a custom flyback transformer with creepage/clearance compliance, optocoupler-based feedback, and Y-capacitor filtering. While the board itself is not pre-certified, its layout and component selection align with common safety agency test criteria for Class II, double-insulated auxiliary supplies.

Can the output voltage be adjusted, and how?

No - the output is fixed at 12 V by the transformer turns ratio and feedback resistor network. Adjustment would require modifying the secondary winding, optocoupler bias resistors, and potentially the compensation network on the COMP pin. ST does not provide alternate resistor values or transformer variants for this specific board; voltage change necessitates redesign rather than simple component swap.

What protection features are implemented on this board?

The board implements cycle-by-cycle current limiting (via VIPer06's CS pin), thermal shutdown with hysteresis, delayed overload protection, and open-loop failure protection - the latter enabled only when the auxiliary winding is connected and properly biased. These functions are intrinsic to the VIPer06 IC and do not require external circuitry beyond the designated sense and feedback paths.