A3955SLB

Overview

The A3955SLB is a full-bridge PWM microstepping motor driver designed to drive one winding of a bipolar stepper motor. It supports continuous output currents up to ±1.5 A and operating voltages up to 50 V. The device integrates an internal three-bit nonlinear digital-to-analog converter for current control in full-, half-, quarter-, or eighth-step modes. Key protection features include internal transient-suppression diodes, thermal shutdown, crossover-current protection, and under-voltage lockout.

Feature Summary

• Integrates a three-bit nonlinear DAC to minimize control lines while enabling microstepping resolution.
• Provides fast, mixed fast/slow, and slow current-decay modes for precise current regulation.
• Includes internal thermal shutdown and under-voltage lockout for system reliability.

Applications

• Bipolar stepper motor drives requiring microstepping capabilities
• General-purpose motion control systems
• Automation equipment with low-speed resonance reduction needs

Procurement Notes

Verify the specific suffix (e.g., SLB vs. SLPTR) against the manufacturer's official datasheet to confirm package type and pinout compatibility. Confirm RoHS compliance status as historical data indicates variations across Allegro product lines. Ensure the ordering part number matches the exact voltage and current ratings required for the target application circuit design.

Selection Notes

Select this component when driving single-winding bipolar stepper motors with microstepping requirements. The integrated nonlinear DAC simplifies interface logic compared to linear DAC solutions. Verify that the load voltage does not exceed the 50 V rating and that peak currents remain within the ±1.5 A continuous limit to ensure safe operation without external heat sinking.

Part Context

The A3955 belongs to Allegro's family of DMOS microstepping motor drivers. It is functionally similar to the A3957 but offers different current handling characteristics. This series is designed for applications requiring high step resolution and reduced torque ripple at low speeds through internal PWM current control mechanisms.

Replacement Considerations

The A3957 is a documented functional substitute within the same product family. Verify pinout compatibility and current rating differences before substitution. No other direct cross-references are confirmed in public documentation.

FAQ

What microstepping resolutions are supported by the internal DAC?

The internal three-bit nonlinear DAC allows for full-, half-, quarter-, and eighth-step microstepping modes.

How does the device handle over-temperature conditions?

The A3955 includes internal thermal shutdown circuitry to protect the device from damage during overheating events.