Allegro MicroSystems A31004LLHALX

Overview

A31004LLHALX from Allegro MicroSystems is a unidirectional linear Hall-effect sensor IC with analog voltage output, designed for high-accuracy displacement and angular position sensing in harsh environments. It delivers 3.3 mV/G sensitivity, 0.5 V quiescent output (QVO), and operates across –40°C to 150°C. Its ratiometric output, programmable QVO and sensitivity temperature coefficients, and integrated dynamic offset cancellation make it suitable for automotive throttle and pedal position feedback systems.

For engineers reviewing the A31004LLHALX datasheet, A31004LLHALX pinout, A31004LLHALX application, or A31004LLHALX equivalent, key selection criteria include its SOT-23W package, south-pole magnetic activation, ±1.5% linearity error, 20 kHz bandwidth, and factory-programmed temperature compensation for QVO and sensitivity drift.

Technical Context

The A31004LLHALX integrates a BiCMOS monolithic circuit featuring a Hall element, temperature-compensating circuitry, high-gain amplifier, clamped low-impedance output stage, and proprietary dynamic offset cancellation. Its chopping frequency is 400 kHz, enabling high-speed suppression of thermal and mechanical stress-induced offset drift.

End-of-line optimization programs non-volatile memory to set QVO ≈ 0.5 V and sensitivity = 3.3 mV/G, while simultaneously programming temperature coefficients for both parameters across the full –40°C to 150°C range. This ensures stable performance without external calibration.

Key Specifications

Pinout & Package

Package: 3-pin SOT-23W (LH), miniature low-profile surface-mount, 2.0 mm × 3.0 mm × 1.0 mm, lead-free with 100% matte-tin plating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar unidirectional linear Hall-effect sensor applications.

Compared with A31004LLHALX, A31004KLHALX-RP3-TC0 offers tighter sensitivity TC but sacrifices 150°C operation and south-pole compatibility, while TLV493D-A1B6 trades analog simplicity and fault-clamp diagnostics for digital flexibility and 3D capability-neither is pin-compatible or drop-in.

Availability

A31004LLHALX is available at Aetrix Electronics and suitable for automotive throttle position sensing, industrial motor feedback, and transmission gear selector applications requiring stable component supply across extended temperature ranges.

Supply support for A31004LLHALX 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 semiconductor company specializing in magnetic sensing, power ICs, and precision motion control solutions.

The A31004 product line delivers high-accuracy, temperature-stable linear Hall-effect sensors for automotive and industrial position feedback where reliability under thermal stress is critical.

FAQ

What magnetic polarity activates the A31004LLHALX?

The A31004LLHALX is south-pole active: it increases output voltage in response to a south-pole magnetic field perpendicular to the branded surface of the package. This is confirmed by the "LL" suffix designation and the functional block diagram labeling. The A31004LLHALX does not respond to north-pole fields in the same directional configuration.

Does the A31004LLHALX require external calibration after soldering?

No, the A31004LLHALX does not require external calibration after soldering. Its non-volatile memory stores factory-programmed sensitivity and QVO values, along with temperature coefficients optimized at end-of-line test. This ensures stable performance across –40°C to 150°C without user adjustment, as verified by the ∆VOUT(Q) ≤ ±20 mV and TCSens = 0.08–0.16 %/°C specifications.

What is the purpose of the output voltage clamps in the A31004LLHALX?

The A31004LLHALX output clamps (VCLPHIGH = 2.87–3.07 V, VCLPLOW = 0.25–0.43 V) serve dual purposes: they limit the analog output to a defined safe range under overload conditions, and they enable short-circuit diagnostics. When VOUT is forced outside these bounds-e.g., by wiring faults-the clamped state provides a deterministic fault signature readable by the host microcontroller, supporting functional safety requirements.

Can the A31004LLHALX operate from a 5 V supply?

No, the A31004LLHALX is specified only for 3.0–3.63 V operation. Its absolute maximum forward supply voltage is 8 V, but electrical characteristics-including sensitivity, QVO, and clamp voltages-are guaranteed only within the 3.0–3.63 V range. Operating at 5 V risks violating ratiometric behavior, exceeding internal regulator limits, and invalidating the ±1.5% linearity and temperature coefficient specs documented for 3.3 V nominal supply.

How does the A31004LLHALX achieve stable performance across temperature cycling?

The A31004LLHALX achieves stable performance across temperature cycling via three integrated mechanisms: (1) factory-programmed QVO and sensitivity temperature coefficients stored in non-volatile memory; (2) proprietary dynamic offset cancellation using high-frequency chopping (400 kHz); and (3) BiCMOS process technology enabling low-drift amplifiers. These ensure ≤±2% sensitivity hysteresis (∆SensPKG) and ≤±20 mV QVO drift after thermal cycling from –40°C to 150°C and back.