STMicroelectronics EVALSP820-XS

Overview

EVALSP820-XS from STMicroelectronics is an evaluation board for the STSPIN820 advanced 256-microstep bipolar stepper motor driver IC, designed to validate motor control performance in real-time step-clock and direction interface applications. It supports 7–45 V supply, delivers up to 1.5 A_RMS per bridge, features integrated non-dissipative overcurrent protection, and enables full microstepping resolution (1/256) with programmable OFF time and external shunt-based current sensing.

For engineers reviewing the EVALSP820-XS datasheet, EVALSP820-XS pinout, EVALSP820-XS application, or EVALSP820-XS equivalent, this board provides immediate hardware validation of STSPIN820's PWM current control, thermal shutdown behavior, decay mode selection (slow/mixed), and fault reporting via open-drain EN/FAULT pin - critical for 3D printer motion control, CCTV pan-tilt systems, and ATM cash-handling actuation.

Technical Context

The EVALSP820-XS implements a complete reference design around the STSPIN820 QFN-24 (4 × 4 mm) driver, including decoupling capacitors, current-sense shunts, TOFF timing resistor, MODE/DIR/STCK termination networks, and thermal vias under the exposed pad. It replicates production-level PCB layout guidelines per ST's DocID031065 Rev 2, supporting both single- and dual-shunt configurations and enabling direct measurement of sense voltage, FAULT pulse width, and t_ENd propagation delay.

Board-level functionality mirrors the IC's core architecture: dual independent PWM current controllers synchronized to the step clock, microstepping sequencer with 10-bit counter, and full protection stack (UVLO at 6.0 V, thermal shutdown at 160 °C, short-circuit detection, and non-dissipative overcurrent trip at 3–3.5 A). All logic inputs (MODE1–3, DIR, STCK, DECAY, STBY/RESET) are accessible via 0.1" headers for pattern generation and timing analysis.

Key Specifications

Availability

EVALSP820-XS is available at Aetrix Electronics and suitable for 3D printer motion control, ATM cash-handling mechanisms, and CCTV dome camera positioning requiring stable component supply and rapid prototyping validation.

Supply support for EVALSP820-XS 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 power management, motor control, and embedded processing solutions for industrial, automotive, and consumer markets.

The STSPIN family targets high-precision motion control applications, with the STSPIN820 specifically engineered for compact, thermally efficient stepper driver implementations in space-constrained equipment like medical pumps and robotic end-effectors.

FAQ

Does EVALSP820-XS support both unipolar and bipolar stepper motors?

No - EVALSP820-XS is configured exclusively for bipolar stepper motors using the STSPIN820's dual H-bridge architecture. It drives two-phase, four-wire bipolar steppers only; unipolar motor connection is not supported due to missing center-tap routing and incompatible current control topology.

Can the TOFF timing resistor be modified on EVALSP820-XS to adjust PWM OFF time?

Yes - the board includes a dedicated 0805 footprint (R13) for the TOFF resistor, allowing direct replacement to set total OFF time between 13 µs (10 kΩ) and 146 µs (160 kΩ) as specified in ST's electrical characteristics table. Solder jumpers enable quick reconfiguration without PCB redesign.

Is thermal performance validated on EVALSP820-XS under continuous 1.5 A_RMS load?

Yes - ST's reference design uses 10 thermal vias under the QFN-24 exposed pad connected to a 2s2p internal copper plane, achieving R_thJB = 13.6 °C/W. At 1.5 A_RMS, 36 V, and 25 °C ambient, measured junction temperature remains below 115 °C per thermal imaging, well within the 150 °C absolute maximum rating.

Does EVALSP820-XS provide access to the FAULT signal for system-level error handling?

Yes - the EN/FAULT pin is routed to a test point and 0.1" header (J5 pin 2), delivering an open-drain active-low signal that asserts during UVLO, overtemperature, overcurrent, or short-circuit events. External pull-up to 3.3 V or 5 V is provided, enabling direct MCU interrupt input or LED indicator drive.