STMicroelectronics STEVAL-A6986IV2

Overview

STEVAL-A6986IV2 from STMicroelectronics is an automotive-grade evaluation board based on the A6986I synchronous iso-buck DC-DC converter, designed for isolated 5 V supply generation in high-reliability systems. It supports 4–38 V input, delivers up to 5 W isolated output, operates from –40 °C to 135 °C junction temperature, requires no optocoupler, and implements peak current mode control with 300 ns blanking time for transformer-based isolation.

For engineers reviewing the STEVAL-A6986IV2 datasheet, STEVAL-A6986IV2 pinout, STEVAL-A6986IV2 application, or STEVAL-A6986IV2 equivalent, key selection criteria include its AEC-Q100 qualification, forced PWM operation, adjustable soft-start and switching frequency, primary-side current limiting (1.9 A sink), and integrated voltage supervisor for primary output regulation in isolated power architectures.

Technical Context

The board implements an iso-buck topology using the A6986I controller IC, where primary-side regulation eliminates optocoupler dependency and enables precise tracking of secondary output via primary current sensing. The 300 ns blanking time suppresses leakage-induced oscillations, and pulse-by-pulse current sensing on both high-side (R_DS(on) = 180 mΩ) and low-side (R_DS(on) = 150 mΩ) MOSFETs ensures robust overcurrent protection.

Secondary-side voltage stabilization uses a TL431 shunt reference and external power transistor, enabling short-circuit protection through primary reverse current limiting. The board includes an onboard EMI filter (bypassable via R16), isolated ground separation (GND1/GND2/GNDiso), and resistor-divider-based isolated voltage adjustment (V_ISO = 2.49 × (R12 + R13)/R13).

Key Specifications

Availability

STEVAL-A6986IV2 is available at Aetrix Electronics and suitable for automotive power supply design, isolated gate driver biasing, and on-board charger auxiliary supply applications requiring stable component supply, AEC-Q100 compliance, and validated reference implementation.

Supply support for STEVAL-A6986IV2 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, specializing in automotive, industrial, and power management solutions with vertical manufacturing and broad analog/mixed-signal IP.

The STEVAL-A6986IV2 belongs to ST's automotive evaluation board portfolio, developed to accelerate design-in of isolated DC-DC converters for traction inverters, on-board chargers, and domain controllers requiring reinforced insulation and functional safety readiness.

FAQ

What is the purpose of the R16 0 Ω resistor on the STEVAL-A6986IV2 board?

R16 provides a configurable bypass path for the onboard EMI filter located on the bottom side of the PCB. When populated with a 0 Ω resistor, it shorts across the filter components, allowing direct VIN connection for testing scenarios where EMI filtering is unnecessary or may interfere with measurement accuracy.

How is isolated output voltage adjusted on the STEVAL-A6986IV2?

V_ISO is set by the resistor divider formed by R12 and R13, following V_ISO = 2.49 × (R12 + R13)/R13. Fine-tuning may require adjusting R11 to compensate for tolerances and ensure accurate regulation across temperature and load conditions.

Why does the A6986I controller not require an optocoupler?

The A6986I achieves isolated regulation using primary-side sensing: it monitors primary current and voltage to infer secondary output behavior, eliminating optocoupler dependency while maintaining ±3% output accuracy and enabling faster transient response than traditional feedback loops.

What protection features are implemented on the STEVAL-A6986IV2 board?

The board integrates overvoltage protection, thermal shutdown, internal primary current limiting, and short-circuit protection on the secondary side via primary reverse current limiting. Pulse-by-pulse current sensing on both HS and LS MOSFETs provides cycle-by-cycle fault detection and shutdown within one switching period.