STMicroelectronics STEVAL-A6986IV3

Overview

STEVAL-A6986IV3 from STMicroelectronics is an evaluation board based on the A6986I isolated synchronous DC-DC controller, implementing an inverting buck-boost (isobuck-boost) topology for gate driver power supply. It delivers four isolated dual-voltage outputs (18 V/−5 V or 15 V/−8 V selectable per channel), supports 4–28 V input, and provides up to 180 mA on one output and 60 mA on each of three others for high-side/low-side IGBT or MOSFET drivers in three-phase inverters.

For engineers reviewing the STEVAL-A6986IV3 datasheet, STEVAL-A6986IV3 schematic, STEVAL-A6986IV3 application in EV on-board chargers or three-phase motor drives, or STEVAL-A6986IV3 equivalent evaluation platforms, this board enables rapid validation of isolated dual-rail gate drive power with ±1% post-regulation accuracy and no optocoupler.

Technical Context

The board implements an isobuck-boost primary stage using the A6986I controller (250 kHz switching frequency, 150 V internal switch rating), generating a negative primary output that feeds four independent transformer secondaries. Each secondary uses LDH40PURY LDOs for positive rail regulation and TL431BL3T shunt references for negative rail regulation.

Four slide-DPDT microswitches enable per-channel selection between two regulated voltage pairs (18 V/−5 V or 15 V/−8 V); all four outputs feature dedicated post-regulation with <±1% accuracy, peak/reverse current protection, and thermal shutdown.

Key Specifications

Availability

STEVAL-A6986IV3 is available at Aetrix Electronics and suitable for EV on-board chargers, three-phase motor inverters, and DC fast charging station auxiliary power supply designs requiring stable component supply, rapid prototyping capability, and validated isolated gate driver bias architecture.

Supply support for STEVAL-A6986IV3 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 chips, and silicon carbide devices for automotive, industrial, and consumer applications.

The STEVAL-A6986IV3 belongs to ST's power evaluation platform portfolio, specifically developed to accelerate adoption of isolated gate driver power solutions for high-reliability traction inverters and EV charging systems.

FAQ

What is the primary purpose of the STEVAL-A6986IV3 evaluation board?

This board demonstrates the A6986I controller in an isobuck-boost configuration to deliver four precisely regulated, isolated dual-voltage outputs for driving high-side and low-side power switches. It targets validation of gate driver bias supplies in three-phase inverters, eliminating optocouplers while maintaining ±1% regulation accuracy across all rails.

Can the output voltage pairs be changed dynamically during operation?

No - voltage pair selection (18 V/−5 V or 15 V/−8 V) is set per channel via physical slide-DPDT microswitches and is static during operation. The switches must be configured before power-up; no digital interface or runtime reconfiguration is supported on this evaluation board.

Which components provide post-regulation on each isolated output?

Each output uses an LDH40PURY low-dropout LDO for the positive rail and a TL431BL3T shunt voltage reference for the negative rail. This dual-stage post-regulation achieves <±1% accuracy without optocouplers and supports the extended 22 V input range of the LDH40.

Is the STEVAL-A6986IV3 compliant with automotive qualification standards?

Yes - the underlying A6986I controller is qualified to AEC-Q100 Grade 1 (−40 °C to +125 °C), and the board uses automotive-grade passives and regulators (LDH40PURY, TL431BL3T). The design targets automotive on-board charger and traction inverter auxiliary power applications.