STMicroelectronics STEVAL-ISA135V1

Overview

STEVAL-ISA135V1 from STMicroelectronics is an isolated 4 W, 12 V flyback evaluation board based on the VIPer06HS offline high-voltage converter IC. It accepts universal AC input (85–265 VAC), delivers up to 333 mA at ±5% regulation, achieves ≥71% efficiency, and incorporates thermal shutdown, delayed overload protection, and open-loop failure detection via auxiliary winding.

For engineers reviewing the STEVAL-ISA135V1 datasheet, STEVAL-ISA135V1 schematic, STEVAL-ISA135V1 application notes, or STEVAL-ISA135V1 bill of materials, this board enables rapid validation of VIPer06HS-based low-power isolated AC/DC conversion in industrial control interfaces, IoT sensor hubs, and smart meter auxiliary supplies.

Technical Context

The STEVAL-ISA135V1 implements a primary-side regulated, transformer-isolated flyback topology with fixed 115 kHz switching frequency and built-in frequency jittering to reduce EMI. Its control loop relies on auxiliary winding feedback for output voltage sensing without secondary-side optocoupler or TL431.

VIPer06HS integration provides cycle-by-cycle current limiting with adjustable threshold, on-chip soft-start, and auto-restart after fault clearance. Protection features include thermal shutdown with hysteresis, delayed overload response, and open-loop detection triggered by loss of auxiliary winding signal.

Key Specifications

Availability

STEVAL-ISA135V1 is available at Aetrix Electronics and suitable for industrial control interfaces, IoT sensor hubs, and smart meter auxiliary supplies requiring stable component supply and fast design validation cycles.

Supply support for STEVAL-ISA135V1 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, sensors, and analog devices for industrial, automotive, and consumer applications.

This evaluation board belongs to ST's STEVAL (ST Evaluation) series, purpose-built to accelerate prototyping and qualification of ST's VIPer™ offline AC/DC converters in cost-sensitive, space-constrained low-power systems.

FAQ

What is the primary function of the STEVAL-ISA135V1?

The STEVAL-ISA135V1 is a fully assembled and tested evaluation board that demonstrates a 4 W, 12 V isolated flyback power supply using the VIPer06HS controller. It serves as a reference design for validating primary-side regulation, EMI performance, and protection behavior in real-world low-power AC/DC applications without secondary-side feedback components.

Does STEVAL-ISA135V1 require external optocouplers or TL431 for regulation?

No. The board uses primary-side regulation via the VIPer06HS and auxiliary winding feedback, eliminating the need for optocouplers or TL431. Output voltage accuracy (±5%) is maintained across line, load, and temperature variations using internal compensation and auxiliary winding sensing.

What protection mechanisms are implemented on this board?

The board implements thermal shutdown with hysteresis, delayed overload protection (to avoid nuisance tripping during transient loads), and open-loop failure detection triggered by loss of auxiliary winding signal-ensuring safe operation under fault conditions without external supervision circuitry.

Can STEVAL-ISA135V1 be modified for different output voltages?

Yes-output voltage can be adjusted by modifying the auxiliary winding turns ratio and associated resistor divider network on the VIPer06HS feedback pin. ST provides design guidelines and transformer specifications in AN4359 and the VIPer06HS datasheet to support custom output derivations while preserving safety isolation and regulation performance.