STMicroelectronics EVAL6228QR

Overview

EVAL6228QR from STMicroelectronics is a compact reference design board for the L6228Q two-phase bipolar stepper motor driver IC, implementing full-bridge PWM current control with 1 A DC output capability per channel, 8–52 V supply range, and support for half/full-step modes, direction (CW/CCW), decay mode (SLOW/FAST), and diagnostic signaling - used in precision motion control subsystems for industrial automation and lab equipment.

For engineers reviewing the EVAL6228QR datasheet, EVAL6228QR pinout, EVAL6228QR application, or EVAL6228QR equivalent, this board enables rapid validation of L6228Q-based stepper drive topologies including charge-pump high-side gate drive, external PWM-filtered current reference generation, overcurrent/overtemperature diagnostics, and layout-sensitive power switching at up to 100 kHz.

Technical Context

The EVAL6228QR implements the L6228Q's integrated dual H-bridge architecture with internal phase sequence generator, PWM current regulation via REFA/REFB analog inputs, and real-time fault detection routed to the DIAG pin. It uses BAT46SW diodes and 220 nF capacitors (C1/C4) in a bootstrap charge-pump circuit to supply the high-side MOSFET gates.

Input logic lines (CLOCK, CW/CCW, CONTROL, HALF/FULL, EN, RESET) are pulled low by 100 kΩ resistors and accept 0–5 V TTL-compatible signals. Off-time t_OFF (~50 µs) is set by R6/C6 and R7/C7 networks, while overcurrent disable timing (t_DISABLE ≈ 200 µs) is configured by R1/C5.

Key Specifications

Availability

EVAL6228QR is available at Aetrix Electronics and suitable for industrial motion control prototyping, stepper driver reference design validation, and embedded motor control firmware development requiring stable component supply and documented layout practices.

Supply support for EVAL6228QR 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 analog, mixed-signal, power, and microcontroller solutions for industrial, automotive, and consumer markets.

The EVAL6228QR belongs to ST's motor control evaluation board product line, developed specifically to accelerate adoption of the L6228Q stepper driver IC in compact, thermally efficient, and EMC-aware motion subsystems.

FAQ

What is the purpose of the BAT46SW diode and C1/C4 capacitors on EVAL6228QR?

The BAT46SW diode and 220 nF/25 V (C1) and 10 nF/25 V (C4) capacitors form a charge-pump circuit that generates the gate-drive voltage for the high-side DMOS transistors inside the L6228Q. This eliminates the need for an external high-voltage bias supply and ensures reliable switching across the full 8–52 V input range.

How is current regulation implemented on EVAL6228QR?

Current regulation uses external analog reference voltages applied to REFA and REFB pins, each scaled to set peak winding current via internal PWM comparators. Reference sources can be resistor dividers from a microcontroller rail or low-pass-filtered PWM outputs - R11/C8 and R13/C9 provide such filtering paths on the board.

Can EVAL6228QR drive unipolar stepper motors?

No - EVAL6228QR is designed exclusively for two-phase bipolar stepper motors. The L6228Q integrates dual full H-bridges with synchronous rectification and current sensing, which require four-wire bipolar motor connections (OUT1A/OUT2A and OUT1B/OUT2B). Unipolar motors lack the center-tapped winding configuration needed for this topology.

What thermal management features does EVAL6228QR include?

EVAL6228QR incorporates a dedicated GND copper pour area beneath the L6228Q QFN package to enhance heat dissipation, leveraging the IC's 42 °C/W junction-to-ambient thermal resistance. The compact 27 × 32 mm layout minimizes trace inductance and improves thermal coupling between power components and ground plane.