STMicroelectronics STEVAL-ISA112V1

Overview

STEVAL-ISA112V1 from STMicroelectronics is a non-isolated flyback demonstration board implementing a 12 V/4 W single-output AC-DC power supply using the VIPER06HN offline high-voltage PWM controller. It operates across universal mains input (90–265 VAC), delivers 350 mA continuous output, achieves <30 mW standby consumption at 230 VAC, and meets EN55022 Class-B EMC and EuP Lot 6 energy efficiency requirements.

For engineers reviewing the STEVAL-ISA112V1 datasheet, STEVAL-ISA112V1 schematic, STEVAL-ISA112V1 transformer layout, or STEVAL-ISA112V1 application notes, this board serves as a validated reference design for low-power offline SMPS in white goods, LED drivers, and home automation systems-enabling rapid evaluation of VIPER06HN-based flyback topologies with full protection features.

Technical Context

The board implements a fixed-frequency, discontinuous conduction mode (DCM) flyback converter optimized for universal input and ultra-low standby power. It uses the VIPER06HN's integrated 800 V avalanche-rugged MOSFET (R_DS(on) ≤ 32 Ω) and internal HV-startup circuitry, with dual supply options (output-derived or self-supplied via auxiliary winding).

Protection mechanisms include thermal shutdown, short-circuit foldback, feedback disconnection detection, and overload limiting. The transformer (Magnetica 1921.0040) features 1.2 mH primary inductance, 6.11:1 primary-to-secondary turns ratio, and 2.8% leakage inductance-key to stable regulation and EMI control.

Key Specifications

Availability

STEVAL-ISA112V1 is available at Aetrix Electronics and suitable for white goods power supplies, LED driver reference designs, home automation controllers, and low-power industrial sensors requiring stable component supply and pre-validated safety-compliant topology implementation.

Supply support for STEVAL-ISA112V1 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 devices, and MEMS sensors for industrial, automotive, and consumer applications.

This board belongs to ST's STEVAL evaluation platform family, engineered to accelerate adoption of VIPerPlus offline converters by delivering fully tested, documented, and safety-certified reference designs for sub-5 W AC-DC conversion.

FAQ

What is the purpose of the J1 jumper on STEVAL-ISA112V1?

J1 selects the VIPER06HN supply mode: when closed, the IC is powered from the 12 V output rail; when open, it uses the auxiliary winding for self-supply. This allows direct comparison of standby power and thermal performance between configurations-critical for optimizing no-load losses in energy-sensitive applications.

Does STEVAL-ISA112V1 support output voltage adjustment?

No-the output is fixed at 12 V by the resistor divider network (RfbH1/RfbH2/RfbL1/RfbL2) and transformer turns ratio. Output voltage change requires modifying the feedback resistors and verifying loop stability and regulation accuracy per the VIPER06HN datasheet guidelines.

Can STEVAL-ISA112V1 be used for isolated power supply designs?

No-it implements a non-isolated flyback configuration where primary and secondary grounds share a common reference. For isolation, a standard flyback with separate primary/secondary windings and reinforced insulation must be used; this board is intended for cost-sensitive, space-constrained non-isolated applications only.

What transformer is used, and is it replaceable?

The board uses Magnetica part 1921.0040: a custom flyback transformer with 1.2 mH primary inductance, 6.11:1 turns ratio, and 2.8% leakage inductance. It is mounted and soldered; replacement requires matching all electrical and safety parameters-including creepage/clearance-to maintain EN55022 and EuP compliance.