Allegro MicroSystems A1309LLHLX-RP9-T

Overview

A1309LLHLX-RP9-T from Allegro MicroSystems is a reverse-polarity, ratiometric linear Hall-effect sensor IC in a 3-pin SOT-23W package, delivering –9 mV/G sensitivity with ±1.5% linearity error and ±1.5% symmetry error across –40°C to +150°C. It features programmable temperature coefficients for quiescent output (QVO) and sensitivity, dynamic offset cancellation, and output voltage clamps for short-circuit diagnostics-enabling high-accuracy angular and displacement sensing in automotive throttle and brake pedal position systems.

For engineers reviewing the A1309LLHLX-RP9-T datasheet, A1309LLHLX-RP9-T pinout, A1309LLHLX-RP9-T application, or A1309LLHLX-RP9-T equivalent, this device supports critical design decisions involving magnetic field linearity, thermal stability over extended temperature ranges, ratiometric supply rejection, and fault-detecting analog output behavior in safety-conscious automotive subsystems.

Technical Context

The A1309LLHLX-RP9-T integrates a BiCMOS monolithic circuit with a Hall element, high-gain amplifier, tuned low-pass filter, and proprietary dynamic offset cancellation. Its chopper-stabilized architecture operates at 400 kHz to suppress thermal and mechanical stress-induced QVO drift, sustaining precision across full temperature range.

It implements ratiometric operation: QVO = 2.5 V (50% of 5 V supply), output clamps at 4.5 V (high) and 0.55 V (low), and includes undervoltage lockout (UVLO) with 2.5 V turn-off and 3 V turn-on thresholds-ensuring robust startup and fail-safe behavior under supply transients.

Key Specifications

Pinout & Package

Package: 3-pin SOT-23W (2.0 mm × 3.0 mm × 1.0 mm, low-profile surface-mount), lead-free with 100% matte-tin plating, thermal resistance R_θJA = 110°C/W on 2-layer PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with A1309LLHLX-9-T, the A1309LLHLX-RP9-T eliminates need for external polarity inversion; compared with TLV493D-A1B6, it delivers plug-and-play analog output with integrated clamps and UVLO-reducing BOM count and validation effort in single-axis, high-reliability automotive sensing.

Availability

A1309LLHLX-RP9-T is available at Aetrix Electronics and suitable for automotive throttle position sensing, brake pedal monitoring, steering angle detection, and transmission gear selector applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for A1309LLHLX-RP9-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 semiconductor company specializing in high-performance magnetic sensing and power ICs for automotive and industrial markets.

The A1309 series belongs to Allegro's linear Hall-effect sensor product line, engineered specifically for high-accuracy, temperature-stable angular and linear position sensing in demanding automotive powertrain and chassis systems.

FAQ

What is the polarity configuration of the A1309LLHLX-RP9-T?

The A1309LLHLX-RP9-T features reverse polarity output: its sensitivity is –9 mV/G, meaning the output voltage decreases in response to an increasing south-pole magnetic field. This is confirmed in the Selection Guide and Electrical Characteristics table, where Sens is specified as –9.27 to –8.73 mV/G. The "RP" suffix explicitly denotes reverse polarity, distinguishing it from forward-polarity variants like A1309LLHLX-9-T. This polarity enables direct compatibility with south-pole dominant actuator designs without external signal inversion circuitry.

Does the A1309LLHLX-RP9-T require an external bypass capacitor?

Yes, the A1309LLHLX-RP9-T requires a 0.1 µF ceramic bypass capacitor between VCC and GND, as specified in the Operating Characteristics section and Typical Application Circuit (Figure 6). This capacitor stabilizes the internal regulator, suppresses supply noise, and ensures proper operation of the chopper-stabilized amplifier. Omission risks increased output noise, reduced immunity to supply transients, and potential instability during power-on sequencing-especially critical in automotive environments with high EMI.

How does the A1309LLHLX-RP9-T achieve thermal stability across –40°C to +150°C?

The A1309LLHLX-RP9-T achieves thermal stability through factory-programmed temperature coefficients for both sensitivity (TCSens = 0.08–0.16 %/°C) and quiescent output (QVO), applied during Allegro's end-of-line test at 150°C. Combined with dynamic offset cancellation and chopper stabilization at 400 kHz, these measures limit QVO drift to ≤±10 mV over the full range. This is validated in the DRIFT CHARACTERISTICS table, where ∆VOUT(Q) for A1309LLHLX-RP9-T is specified as –30 to 0 mV at TA = 150°C.

Is the A1309LLHLX-RP9-T AEC-Q100 qualified?

Yes, the A1309LLHLX-RP9-T is AEC-Q100 qualified, as explicitly stated in the FEATURES AND BENEFITS section and confirmed in Revision History entry #14 (April 23, 2026). It meets Grade 0 requirements (–40°C to +150°C), qualifying it for use in powertrain, chassis, and safety-critical automotive applications. This qualification covers stress testing for temperature cycling, humidity, vibration, and ESD-ensuring reliability under real-world vehicle operating conditions.

What is the function of the output voltage clamps in the A1309LLHLX-RP9-T?

The A1309LLHLX-RP9-T features output voltage clamps at VCLPHIGH = 4.5 V and VCLPLOW = 0.55 V (typical, at 25°C with 10 kΩ load), which serve dual purposes: (1) they protect downstream circuitry from overvoltage/undervoltage during fault conditions (e.g., shorted output), and (2) they enable passive short-circuit diagnostics-since a stuck-low or stuck-high output outside these bounds indicates wiring or sensor failure. These clamps scale ratiometrically with VCC, maintaining diagnostic integrity across supply variations.