STMicroelectronics STEVAL-ISA110V1

Overview

STEVAL-ISA110V1 from STMicroelectronics is a 12 V/12 W non-isolated flyback demonstration board based on the VIPER26LN high-voltage PWM controller, designed for universal AC input (90–264 VAC) and delivering 12 V at 1 A continuous output. It features <30 mW standby consumption at 265 VAC, >85% average efficiency, and full protection against overload, feedback disconnection, and overheating.

For engineers reviewing the STEVAL-ISA110V1 datasheet, STEVAL-ISA110V1 application schematic, STEVAL-ISA110V1 bill of materials, or STEVAL-ISA110V1 evaluation board alternatives, this reference design enables rapid validation of VIPER26LN-based offline power supplies in industrial adapters, IoT wall plugs, and low-power auxiliary rails where compact non-isolated topology is acceptable.

Technical Context

The board implements a fixed-frequency (60 kHz) flyback converter with frequency jittering to reduce EMI emissions, operating in discontinuous conduction mode (DCM) across universal mains input. It uses an integrated VIPER26LN IC with 800 V avalanche-rugged drain, onboard soft-start, and auto-restart after fault clearance.

Output regulation relies on primary-side sensing via optocoupler-free feedback using the VIPER26LN's COMP pin and external resistor divider (R4a/R4b), achieving ±5% line/load regulation and 50 mV peak-to-peak high-frequency ripple at full load.

Key Specifications

Availability

STEVAL-ISA110V1 is available at Aetrix Electronics and suitable for industrial AC/DC adapter development, IoT edge node auxiliary power supply design, and low-power embedded system prototyping requiring stable component supply and documented reference implementation.

Supply support for STEVAL-ISA110V1 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 devices for industrial, automotive, and consumer markets.

This board belongs to ST's STEVAL (ST Evaluation) series - purpose-built reference designs that demonstrate specific ICs (here, VIPER26LN) in real-world topologies to accelerate power supply development for cost-sensitive, space-constrained applications.

FAQ

Is STEVAL-ISA110V1 isolated or non-isolated?

STEVAL-ISA110V1 is a non-isolated flyback design. Though it uses a transformer (T1), the output shares ground with the input bridge rectifier's negative rail - no reinforced insulation or safety isolation barrier is implemented. It is intended only for applications where user-accessible parts are fully enclosed and double-insulated per IEC 62368-1.

What is the role of the VIPER26LN on this board?

The VIPER26LN serves as the integrated high-voltage PWM controller and power switch, combining an 800 V avalanche-rugged MOSFET, current-mode control, 60 kHz oscillator with jittering, soft-start, and protection circuitry (thermal shutdown, open-loop detection, delayed overload). It eliminates need for external gate drivers or error amplifiers.

Can STEVAL-ISA110V1 be modified for 5 V or 24 V output?

Yes - output voltage is set by the R4a/R4b feedback divider on the VIPER26LN COMP pin. To change output, recalculate the resistor ratio per VIPER26LN datasheet Equation 10, verify loop stability with compensation capacitor C6, and confirm transformer T1's secondary turns ratio supports the new voltage under worst-case load and line conditions.

Does this board include EMI filtering components?

Yes - it integrates a common-mode choke (L1), X-capacitor (C1), Y-capacitors (C7/C8), and snubber network (R4b/C6) to meet EN55022 Class B conducted and radiated emission limits. Layout follows ST's recommended creepage/clearance guidelines, and filtering effectiveness is validated in the referenced data brief (Doc ID 024123 Rev 1).