Allegro MicroSystems A2919SLB

Overview

A2919SLB from Allegro MicroSystems is a dual full-bridge PWM motor driver IC designed to control both windings of a bipolar stepper motor or drive two DC motors bidirectionally. It supports 45 V motor supply voltage, delivers 750 mA continuous output current per bridge, and features internal PWM current control with selectable current limits (0%, 41%, 67%, 100%) via logic inputs I0/I1 - used in industrial motion control systems requiring precise microstepping.

For engineers reviewing the A2919SLB datasheet, A2919SLB pinout, A2919SLB application, or A2919SLB equivalent, key selection considerations include its 24-pin SOICW package with exposed thermal tabs, integrated clamp/flyback diodes, thermal shutdown at 170°C, and fixed off-time PWM control architecture optimized for half- and quarter-step operation.

Technical Context

The A2919SLB implements two independent H-bridge channels, each with PHASE-controlled direction and I0/I1-selectable current limit thresholds derived from VREF and external sense resistors. Its monostable-based PWM uses external RC timing components (RT/CT) to set fixed off-time (~46 μs typical), enabling slow-decay current regulation above audible frequencies.

Each bridge integrates source/sink drivers with <1.8 V total saturation voltage at 500 mA, ground-clamp and flyback diodes for inductive transient protection, and internal dead-time (~2 μs) to prevent shoot-through during PHASE transitions. Thermal shutdown disables all outputs at TJ = 170°C and recovers at 145°C.

Key Specifications

Pinout & Package

Package: 24-pin SOICW (suffix LB) with exposed thermal tab - batwing construction enhances thermal dissipation (θ_JA = 55°C/W), enabling continuous dual-bridge operation at 500 mA in ambient up to +85°C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual full-bridge motor driver applications.

Compared with A2919SLB, A3982SLB offers higher current and digital control abstraction but removes direct I0/I1 logic interface, while DRV8825 provides finer microstepping at the cost of external protection components and non-pin-compatible layout.

Availability

A2919SLB is available at Aetrix Electronics and suitable for industrial motion control, lab automation, medical imaging stage control, and factory test fixture actuation requiring stable component supply despite end-of-life status.

Supply support for A2919SLB 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

Allegro MicroSystems is a U.S.-based designer of high-performance magnetic sensing and power ICs, headquartered in Worcester, Massachusetts, with over 40 years of analog/mixed-signal expertise.

The A2919SLB belongs to Allegro's legacy dual H-bridge motor driver product line, engineered specifically for cost-sensitive, thermally constrained stepper and DC motor applications in industrial and instrumentation equipment.

FAQ

What is the maximum motor supply voltage supported by the A2919SLB?

The A2919SLB supports a maximum motor supply voltage (VBB) of 45 V. This rating is absolute and must not be exceeded under any condition, including transient spikes. Operation at 45 V enables direct connection to standard 24 V and 36 V industrial motor rails while retaining headroom for back-EMF during deceleration. The A2919SLB maintains specified performance across its full 10 V to 45 V operating range.

Does the A2919SLB require external flyback diodes for inductive load protection?

No, the A2919SLB does not require external flyback diodes. It integrates internal clamp and flyback diodes for both bridges, eliminating the need for eight discrete external diodes. These on-chip diodes handle inductive kickback during current decay, reducing BOM count and PCB area. Their forward voltage is specified at 1.6–2.0 V at 750 mA, consistent with the device's low-saturation design goals.

How does the A2919SLB implement quarter-step operation?

The A2919SLB achieves quarter-step operation through digital selection of four discrete current levels (0%, 41%, 67%, 100%) via I0 and I1 logic inputs, combined with PHASE-controlled winding polarity. In one quadrant, the sequence applies 100%/0%, 100%/41%, 67%/67%, 41%/100%, and 0%/100% to Phase 1/Phase 2 - generating 16 distinct positions per full step without external microstepping controllers.

What thermal protection mechanism does the A2919SLB use?

The A2919SLB incorporates a junction temperature-based thermal shutdown circuit that disables all output drivers when the die temperature reaches 170°C. Outputs automatically re-enable once the junction cools to approximately 145°C. This hysteresis prevents oscillation near the trip point. The protection is internal and requires no external components - it complements the device's low-output-saturation design and batwing SOICW package for passive thermal management.

Is the A2919SLB still in production, and what does "Last Time Buy" mean for this part?

The A2919SLB is classified as Last Time Buy (LTB) with a final order deadline of October 29, 2010. It remains available through Aetrix Electronics for existing customer applications but is obsolete for new designs. No samples are available, and Allegro no longer manufactures it. Customers designing new products should consider validated alternatives like the A3982SLB or DRV8825, while legacy programs may rely on Aetrix's managed inventory and traceable sourcing.