News

High-Speed, High-Resolution Stepper Motor-Driver Board

May 30, 2018 by Paul Shepard

STMicroelectronics' EVALSP820-XS motor-driver board brings ST's industrial-control expertise to the RAMPS (RepRap Arduino Mega Pololu Shield) open-source 3D-printer platform, enabling 3D printer makers to unleash the full potential of their machines for faster printing and smoother surface finish.

The RAMPS modular platform is making Fused Filament Fabrication (FFF) 3D printing accessible to makers, small businesses, and home users, for fast prototyping, making replacement parts, or education.

The Arduino Mega 2560, or Arduino DUE, baseboard provides basic control, ready for users to plug-in their own choice of motor driver, extruder controller, and any other desired functions using Mega-compatible expansion shields.

As a plug-and-play expansion board, ST's EVALSP820-XS can drive RAMPS printers at an unprecedented speed for greatly increased throughput ensuring superior smoothness with microstepping resolution from ½-step to 1/256-step per microstep.

Key to this giant leap in 3D-printing performance is ST's STSPIN820 stepper-driver IC. The STSPIN820 embeds high-speed motor-control input circuitry and algorithms developed for industrial applications. It also integrates a powerful 1.5Arms output stage in the ultra-compact 4mm x 4mm QFN package. Industrial ruggedness is assured with comprehensive built-in protection including under-voltage lockout, over-current/short-circuit protection, and thermal shutdown.

The board can be used in other projects, too, to accelerate development of smooth, high-speed stepper control for equipment such as surveillance-camera platforms, textile-manufacturing or sewing machines, medical devices, cash-handling machines, office and home automation, point-of-sale terminals, and robotics. Applications are expected to include:

  • 3D printers
  • Medical equipment
  • Textile and sewing machines
  • CCTV, security and dome cameras
  • Robotics
  • ATM and cash handling machines
  • Office and home automation
  • POS

With its 7V-45V operating-voltage range and simple host interface comprising step-clock and direction-input pins, the STSPIN820 is versatile, economical, and easy to integrate.

Summary of features:

  • Operating voltage: 7 V to 45 V
  • Continuous current up to 1.5 A per phase
  • Maximum current up to 2.5 A per phase
  • Integrated low RDS(ON) power stages (HS + LS = 1 Ω typ.)
  • Microstep resolution easily settable through jumpers: full-step, 1/2, 1/4, 1/8, 1/16, 1/32, 1/128 and 1/256 of step
  • Simple step and direction control interface
  • Adjustable current control through a potentiometer to set the ref. voltages
  • Embedded PWM current control with selectable decay mode (fast or slow)
  • Full set of embedded protections
    • Non-dissipative overcurrent
    • Undervoltage lockout
    • Thermal shutdown
    • Short-circuit
  • Compatible with RAMPS and similar open source solutions for FFF 3D printers
  • Very compact footprint: 15 x 20 mm

The EVALSP820-XS expansion board is available now, priced $6.90, from distributors or directly from STMicroelectronics.