Allegro MicroSystems A4481KLJTR-T

Overview

A4481KLJTR-T from Allegro MicroSystems is an automotive-grade 5 V ±1% linear regulator delivering up to 50 mA output current, operating from 5.25–40 V input with 50 V load dump tolerance and short-to-battery protection up to 32 V. It integrates Power OK (POK) flag, high-voltage ENB enable input (rated to 50 V), foldback overcurrent protection, and thermal shutdown - designed for microcontroller power rails in harsh automotive environments.

For engineers reviewing the A4481KLJTR-T datasheet, A4481KLJTR-T pinout, A4481KLJTR-T application, or A4481KLJTR-T equivalent, key selection criteria include its AEC-Q100 qualification, ±1% output accuracy across –40°C to +150°C, 35°C/W junction-to-ambient thermal resistance in eSOIC-8 package, and fault diagnostics via open-drain POK output.

Technical Context

The A4481KLJTR-T implements a single LDO regulator core with integrated UVLO (4.75–5.2 V start/stop), foldback current limiting (–13 to –35 mA at VOUT = 0 V), and dual-stage VOUT monitoring for UV/OV protection with 15–50 mV hysteresis. Its ENB input features 100 kΩ internal pull-down and 10–25 µs deglitch filtering to reject PCB noise.

Protection architecture includes independent short-to-battery tolerance (up to 32 V on VOUT, regardless of VIN), thermal shutdown at 165°C with 15°C hysteresis, and input undervoltage lockout that disables regulation below ~4.55 V. The POK output asserts low on ENB deactivation, UVLO, TSD, or VOUT UV/OV events.

Key Specifications

Pinout & Package

Package: 8-pin eSOIC (exposed thermal pad), RoHS-compliant, matte-tin leadframe plating. Thermal pad must be soldered to PCB ground plane with ≥6 thermal vias for optimal RθJA performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar automotive LDO regulator applications.

Compared with TLV73350PDBVR and TPS7B8750QKVURQ1, the A4481KLJTR-T uniquely combines Grade 0 temperature range, VOUT short-to-battery tolerance up to 32 V, foldback OCP, and integrated POK - making it the only choice for safety-critical sensor and transceiver supplies in extreme under-hood environments.

Availability

A4481KLJTR-T is available at Aetrix Electronics and suitable for automotive ECU sensor power, CAN/LIN transceiver bias, and ADAS camera module supply requiring stable component supply across extended temperature and high-reliability production cycles.

Supply support for A4481KLJTR-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, power ICs, and motor driver solutions for automotive and industrial markets.

The A4481 product line delivers fault-protected linear regulators engineered specifically for automotive power domains requiring AEC-Q100 compliance, load dump survival, and diagnostic visibility in engine control, body electronics, and ADAS subsystems.

FAQ

What is the maximum ambient temperature for continuous operation of the A4481KLJTR-T?

The A4481KLJTR-T is rated for continuous operation from –40°C to +150°C ambient temperature, validated per AEC-Q100 Grade 0 requirements. Its thermal design uses an eSOIC-8 package with exposed pad and RθJA = 35°C/W, enabling full 50 mA output at +150°C only when VIN ≤ 5.35 V; higher input voltages require derating per Figure 2 in the datasheet. Always verify junction temperature using PDISS = (VIN – 5 V) × IOUT + VIN × 3.4 mA.

Does the A4481KLJTR-T require external capacitors, and what values are recommended?

Yes, the A4481KLJTR-T requires both input and output capacitors. CIN ≥ 2.2 µF (X5R/X7R ceramic, 10 V+ rating) must be placed close to VIN/GND pins. COUT must be 3–10 µF (X5R/X7R, 10 V+); for short-to-battery resilience, use 50–100 V-rated capacitors. The device is stable with all capacitor types meeting these ranges, but improper placement or undersized values will degrade transient response and cause POK false triggers.

How does the Power OK (POK) output function on the A4481KLJTR-T?

The POK output on the A4481KLJTR-T is an open-drain signal that pulls low during ENB deactivation, input UVLO, thermal shutdown, or VOUT UV/OV events. It remains high only when VOUT is within ±10% of 5 V (i.e., 4.5–5.5 V) and all protections are inactive. An external pull-up resistor (typically 10 kΩ to 5 V or 3.3 V) is mandatory; POK low-level voltage is guaranteed ≤400 mV at 4 mA sink current.

Can the ENB pin of the A4481KLJTR-T be tied directly to battery voltage?

Yes, the ENB pin of the A4481KLJTR-T is rated to 50 V and can be connected directly to battery (12 V or 24 V) for automatic wake-up without level-shifting circuitry. Its internal 100 kΩ pull-down ensures default disable state, and 10–25 µs deglitch filtering rejects typical PCB noise. When pulled high above 2 V, the device starts regulation with typical startup time of 1.5 ms into a 50 mA load with ≤4.7 µF output capacitance.

What protection features distinguish the A4481KLJTR-T from standard automotive LDOs?

The A4481KLJTR-T includes five differentiated protections: (1) 50 V load dump rating, (2) VOUT short-to-battery tolerance up to 32 V independent of VIN, (3) foldback overcurrent limiting (–13 to –35 mA), (4) POK fault reporting for all critical failures, and (5) pin-to-pin/pin-to-ground tolerance across all terminals. These features eliminate external protection components required by most competing LDOs in harsh automotive harness environments.