Allegro MicroSystems A4990KLPTR-T

Overview

A4990KLPTR-T from Allegro MicroSystems is an automotive-grade dual full-bridge motor driver IC designed for bipolar stepper and small brush DC motors in high-temperature environments. It delivers ±800 mA per bridge at up to 28 V, features integrated DMOS power FETs with freewheeling diodes, synchronous rectification, and real-time current limiting via external sense resistors. It supports two-phase-on full-step stepper operation and bidirectional DC motor control with active braking in automotive headlamp leveling, throttle actuation, and fuel recirculation systems.

For engineers reviewing the A4990KLPTR-T datasheet, A4990KLPTR-T pinout, A4990KLPTR-T application, or A4990KLPTR-T equivalent, key selection criteria include its 20-pin TSSOP-LP thermally enhanced package, dual independent bridge control logic (IN1–IN4 + INH), open-load and overcurrent diagnostics (EF1/EF2), and automotive-grade thermal robustness (–40°C to +150°C ambient).

Technical Context

The A4990KLPTR-T implements two independent full-bridge drivers with shoot-through prevention via fixed 500 ns dead time and lock-out logic per half-bridge leg. Each bridge uses DMOS power devices with integrated body diodes and supports PWM current regulation using a 4 MHz internal oscillator, 3.5 µs blank time, and 21.7 kHz typical PWM frequency.

Diagnostic architecture includes dual open-drain error flags (EF1/EF2) decoding overvoltage, overtemperature, overcurrent (latched), and open-load faults per Table 3 of the datasheet. Protection functions are hardware-based: VBB UVLO (5.5 V threshold), OVLO (34 V), TJ shutdown (170°C), and short-circuit detection with tSCT = 2 µs delay before latching.

Key Specifications

Pinout & Package

Package: 20-pin TSSOP with exposed thermal pad (LP suffix), 4.4 mm × 6.5 mm × 1.2 mm, lead-free with 100% matte-tin plating. Thermal pad must be soldered to PCB ground plane with ≥4 thermal vias for rated performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TB9051FTG and VNH7040AS, the A4990KLPTR-T offers optimal balance of integration, thermal efficiency, and diagnostic granularity for sub-1 A automotive actuators - delivering embedded current limiting, dual error flags, and 20-pin TSSOP-LP packaging unmatched by either alternative in size-constrained applications.

Availability

A4990KLPTR-T is available at Aetrix Electronics and suitable for automotive headlamp leveling, engine throttle actuation, and HVAC air mix door control requiring stable component supply across extended temperature and long product lifecycles.

Supply support for A4990KLPTR-T 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 and manufacturer of high-performance magnetic sensing and power IC solutions, founded in 1989 and headquartered in Manchester, NH.

The A4990 product line is engineered specifically for automotive electromechanical actuation, emphasizing thermal resilience, integrated diagnostics, and compact packaging for space-constrained under-hood and cabin modules.

FAQ

What is the maximum continuous motor current supported by the A4990KLPTR-T?

The A4990KLPTR-T supports ±800 mA continuous current per full-bridge channel at 28 V and 25°C ambient, derating to ~600 mA at 150°C ambient due to thermal limits. Peak current capability reaches 2.05 A before overcurrent shutdown triggers, enabling brief stall-torque delivery. Actual sustained current depends on PCB copper area, thermal vias under the exposed pad, and ambient airflow - verified per RθJA = 31°C/W on 4-layer boards.

How does the A4990KLPTR-T implement current limiting without external PWM generation?

The A4990KLPTR-T integrates a fixed-frequency (21.7 kHz typical) PWM current regulator with internal 1.2 V reference and 3.5 µs blank time. Users set peak current by selecting external sense resistors (e.g., 150 mΩ for 500 mA) connected between SENS12/SENS34 and GND. The IC autonomously compares sense voltage against VREF/16 and toggles bridge FETs - eliminating need for MCU-based current loop control while maintaining ±10% accuracy across temperature.

Can the A4990KLPTR-T drive a unipolar stepper motor?

No, the A4990KLPTR-T is designed exclusively for bipolar stepper motors and brushed DC motors. Its dual full-bridge topology requires four-terminal, center-tap–free windings (OUT1–OUT2 for Phase A, OUT3–OUT4 for Phase B). Unipolar steppers require five- or six-wire configurations with center taps and single-ended drive - incompatible with the A4990KLPTR-T's bridge architecture and current-sense methodology.

What fault conditions cause latching behavior in the A4990KLPTR-T?

Only overcurrent faults (EF2 = low) trigger latched shutdown in the A4990KLPTR-T - the device remains disabled until INH is pulled low or VBB is cycled. All other faults (open load, overvoltage, overtemperature, undervoltage) are non-latching: outputs resume operation automatically once the fault condition clears and hysteresis thresholds are satisfied. This design ensures fail-safe response to short circuits while allowing graceful recovery from transient overvoltage or temperature excursions.

Is the exposed thermal pad of the A4990KLPTR-T required to be connected to ground?

Yes, the exposed thermal pad on the A4990KLPTR-T must be soldered directly to the PCB ground plane to achieve rated thermal performance (RθJA = 31°C/W). Allegro specifies ≥4 thermal vias (0.3 mm diameter, filled or capped) connecting the pad to inner ground layers. Leaving the pad floating or unconnected increases junction temperature by >40°C at full load and risks premature overtemperature shutdown - violating AEC-Q100 reliability requirements for automotive use.