STMicroelectronics STEVAL-ISA035V1

Overview

STEVAL-ISA035V1 from STMicroelectronics is an evaluation board for the VIPer22A-E, VIPer22ADIP-E, and VIPer22AS-E high-voltage primary-side PWM controllers with integrated 730 V MOSFET. It implements a 7 W (85–265 Vac) or 12 W (195–265 Vac) offline flyback converter in SO-8 or DIP-8 package, featuring fixed 60 kHz switching, current-mode control, auxiliary undervoltage lockout with 6.5 V hysteresis, and auto-restart overvoltage/overcurrent/overtemperature protection. It targets battery charger adapters and standby power supplies.

For engineers reviewing the STEVAL-ISA035V1 datasheet, STEVAL-ISA035V1 pinout, STEVAL-ISA035V1 application, or STEVAL-ISA035V1 equivalent, this board enables rapid validation of VIPer22A-based low-power SMPS designs - including startup behavior under wide VDD range (9–38 V), burst-mode operation at light load, HICCUP-mode overvoltage response, and optocoupler-coupled dual voltage/current regulation per TSM101 feedback architecture.

Technical Context

The STEVAL-ISA035V1 implements a primary-side regulated flyback topology using the VIPer22A-E controller IC. Its operation relies on internal current-mode PWM control with 200 ns current-sense delay and 500 ns blanking time, enabling precise peak current limiting via FB pin current (0–0.9 mA range) and supporting rectangular U-I output characteristics for battery charging.

Startup uses a high-voltage current source tied to the DRAIN pin, charging the VDD capacitor until reaching 14.5 V (VDDon); shutdown occurs at 8 V (VDDoff). Overvoltage protection triggers at 42 V (VDDovp) and resets automatically after VDD falls below VDDoff, while thermal shutdown activates at 170 °C with 40 °C hysteresis.

Key Specifications

Availability

STEVAL-ISA035V1 is available at Aetrix Electronics and suitable for battery charger adapter development, TV/monitor standby power supply qualification, and auxiliary motor control supply prototyping requiring stable component supply and validated reference design support.

Supply support for STEVAL-ISA035V1 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, analog chips, and MEMS sensors for industrial, automotive, and consumer applications.

This evaluation board belongs to ST's VIPer™ AC-DC converter product line, engineered specifically for cost-sensitive, low-power offline SMPS applications where integration of HV start-up, PWM control, and power MOSFET reduces BOM count and simplifies compliance with safety and efficiency standards.

FAQ

What input voltage ranges does STEVAL-ISA035V1 support?

STEVAL-ISA035V1 supports universal AC input from 85 to 265 Vac, delivering 7 W under wide-range conditions and 12 W under European mains (195–265 Vac). The onboard VIPer22A-E controller's 9–38 V VDD operating range ensures reliable startup and regulation across both configurations using auxiliary winding feedback.

How does the board implement overvoltage protection?

The board leverages the VIPer22A-E's internal VDD overvoltage detector, which triggers at 42 V (typical) and forces the device into HICCUP-mode auto-restart. Recovery occurs automatically once VDD drops below 8 V, eliminating need for external latch circuitry and ensuring safe, self-resetting fault handling during transient overvoltage events.

Can STEVAL-ISA035V1 be used for battery charger applications?

Yes - it implements a rectangular U-I output characteristic using TSM101-based secondary-side feedback, enabling simultaneous voltage and current regulation. This allows constant-current charging (e.g., for NiMH or Li-ion) followed by constant-voltage termination, with accurate current limiting set via FB pin current and optocoupler drive.

What is the role of the FB pin on the VIPer22A-E in this design?

The FB pin accepts current (not voltage) input from the optocoupler's phototransistor, directly controlling peak drain current via internal current-mode comparator. At 0.9 mA FB current, the device shuts down; at 0 mA (shorted to SOURCE), it delivers maximum current (~0.7 A). This enables precise, temperature-stable current limiting without external op-amps.