STMicroelectronics STEVAL-ISA019V2

Overview

STEVAL-ISA019V2 from STMicroelectronics is a demonstration board implementing an 80 W, 3-phase auxiliary switched-mode power supply (SMPS) based on the L6565 quasi-resonant PWM controller and STC04IE170HV ESBT® high-voltage switch. It operates with rectified DC input from 250 V to 850 V, delivers 24 V/3.33 A main output and 15 V/0.1 A auxiliary output, and targets motor drive and industrial welding auxiliary power applications.

For engineers reviewing the STEVAL-ISA019V2 datasheet, STEVAL-ISA019V2 schematic, STEVAL-ISA019V2 application, or STEVAL-ISA019V2 bill of materials, this board provides validated flyback topology design, ZVS-capable operation at minimum input voltage, transformer design data for ETD34 core, proportional base driving implementation for ESBT®, and experimental efficiency measurements across full input range.

Technical Context

This board implements a quasi-resonant flyback converter using current-mode control via the 8-pin L6565 IC, enabling valley-switching turn-on to minimize switching losses. The primary-side ESBT® switch STC04IE170HV supports up to 1700 V blocking voltage and is driven by a proportional current transformer network with Zener-clamped peak base pulse.

Design parameters include fixed 50 kHz minimum switching frequency at maximum load and minimum input (250 V), 250 V flyback voltage limit, 1.56 mH primary inductance, 10:1 primary-to-secondary turns ratio, and ETD34 ferrite core with 1.8 mm air gap. Transformer windings use 120 turns primary (0.28 mm wire) and 12 turns secondary (3×0.5 mm parallel).

Key Specifications

Availability

STEVAL-ISA019V2 is available at Aetrix Electronics and suitable for industrial motor drives, welding equipment auxiliary supplies, and high-input-voltage SMPS prototyping requiring stable component supply and reference design validation.

Supply support for STEVAL-ISA019V2 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 devices, analog ICs, and sensors for industrial, automotive, and consumer markets.

The STEVAL-ISA019V2 belongs to ST's ST evaluation board product line, developed specifically to demonstrate high-efficiency, wide-input-voltage auxiliary power architectures for three-phase industrial systems using proprietary ESBT® and quasi-resonant control technologies.

FAQ

What is the purpose of the proportional base driving circuit on STEVAL-ISA019V2?

The proportional base driving circuit uses a current transformer to deliver base current scaled to collector current, preventing ESBT® over-saturation at light loads while maintaining optimal conduction loss. A Zener-clamped RC network adds a short, high-amplitude base pulse to accelerate turn-on and reduce dynamic saturation time, directly improving efficiency at high input voltages.

Can STEVAL-ISA019V2 operate with input voltages above 850 VDC?

Yes - the design includes 200 V clamping margin beyond the 850 V maximum specified input, allowing verified operation up to 1000 VDC. This margin is achieved through the STC04IE170HV's 1700 V V_CEO rating, snubber component derating, and transformer insulation rated per IEC EN60950 for reinforced isolation at >1500 V transient stress.

How does the L6565 enable zero-voltage switching on this board?

The L6565 detects the drain voltage valley via its FB pin and delays switching until the lowest point of the resonant ring-down waveform after demagnetization. At Vin = 250 V, this achieves true ZVS; at higher inputs, it delivers quasi-ZVS (valley switching), reducing turn-on losses and EMI without requiring additional active circuits or complex timing calibration.

Is STEVAL-ISA019V2 compatible with other ST demonstration boards in the ISA019 series?

Yes - STEVAL-ISA019V2 is one of three variants (V1/V2/V3) sharing identical core topology and transformer design, differing only in layout, component placement, and minor BOM optimizations. All three boards implement the same 80 W 3-phase auxiliary SMPS architecture described in Application Note AN2495 and support direct comparison of thermal, noise, and layout-dependent performance metrics.