Analog Devices Inc. LTC4381ADKE-3#PBF

Overview

LTC4381ADKE-3#PBF from Analog Devices is a low-quiescent-current eFuse IC with integrated 9mΩ N-channel MOSFET, fixed latchoff fault behavior, and externally adjustable output voltage clamp. It operates from 4V to 72V input, delivers ≤6µA operating current, withstands 100V input surges, and provides overvoltage/overcurrent protection for automotive 12V/24V/48V systems and avionic surge-critical loads.

For engineers reviewing the LTC4381ADKE-3#PBF datasheet, LTC4381ADKE-3#PBF pinout, LTC4381ADKE-3#PBF application, or LTC4381ADKE-3#PBF equivalent, key selection criteria include its adjustable clamp architecture (no internal 28.5V/47V clamps), latchoff-only fault response, −40°C to 125°C automotive-grade DFN package, and absence of SEL pin functionality - distinguishing it from -1/-2 variants.

Technical Context

The LTC4381ADKE-3#PBF implements MOSFET stress-aware fault timing via a multiplier-driven TMR pin current proportional to V_DS × I_D, enabling dynamic SOA compliance during sustained overvoltage (e.g., load dump) or overcurrent events. Its GATE drive is regulated to V_OUT + 11.5V with internal 17V clamp to OUT, and no ground-referenced output clamp - requiring external Zener at VCC to set clamp voltage.

Unlike LTC4381-1/-2, the -3 variant disables SEL pin functionality and removes internal 28.5V/47V SRC-to-GND clamps; SRC is only clamped to VCC + 10.5V. Reverse input protection supports −60V, and cold-crank operation down to 4V is guaranteed with VCC ≥ 8V during crank.

Key Specifications

Pinout & Package

32-lead (7mm × 5mm) plastic DFN package with exposed thermal pad (Pin 33). RoHS-compliant, moisture sensitivity level 3, rated for −40°C to 125°C junction temperature.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar eFuse protection applications.

Compared with LTC4381ADKE-1#PBF, the LTC4381ADKE-3#PBF trades fixed clamp simplicity for design flexibility via VCC Zener adjustment, while LTC4381IDKE-3#PBF extends thermal range without altering protection behavior - making the ADKE-3 optimal for custom clamp voltages in standard-temperature environments.

Availability

LTC4381ADKE-3#PBF is available at Aetrix Electronics and suitable for automotive load dump protection, avionic surge suppression, and industrial 48V power distribution requiring stable component supply, long-lifecycle assurance, and AEC-Q100-aligned reliability.

Supply support for LTC4381ADKE-3#PBF 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

Analog Devices, Inc. is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision instrumentation, industrial automation, and automotive safety systems.

The LTC4381 product line delivers integrated eFuse solutions with MOSFET SOA guarantees, ultra-low quiescent current, and programmable fault responses - engineered specifically for harsh-environment power path protection in automotive, avionics, and industrial equipment.

FAQ

What is the output voltage clamp mechanism for LTC4381ADKE-3#PBF?

The LTC4381ADKE-3#PBF has no internal 28.5V/47V ground-referenced clamp. Output voltage is controlled solely by clamping the VCC pin with an external Zener diode - e.g., a 68V Zener sets SRC ≈ 78V clamp (VCC + 10.5V). This enables precise, application-specific clamp voltages without modifying the IC's internal architecture. The LTC4381ADKE-3#PBF relies entirely on this external method; SEL pin is unused.

Does LTC4381ADKE-3#PBF support auto-retry after fault conditions?

No. The LTC4381ADKE-3#PBF implements latchoff-only fault behavior: once the TMR pin reaches 1.215V, the MOSFET turns off and remains latched until the ON pin is pulsed low for >100µs or power is cycled. Unlike LTC4381-2/-4 variants, it does not enter automatic cool-down and retry sequences - ensuring fail-safe shutdown during persistent overvoltage or short-circuit faults.

What is the maximum continuous input voltage rating for LTC4381ADKE-3#PBF?

The LTC4381ADKE-3#PBF supports continuous input (IN pin) voltage up to 80V, with absolute maximum rating of 100V for transient surges. Its VCC pin operates from 4V to 72V - meaning for inputs above 72V, VCC must be derived separately (e.g., via LDO) or protected with a Zener clamp to remain within spec. The 100V IN rating enables direct connection to 48V/60V bus systems with headroom for transients.

How is reverse input protection implemented in LTC4381ADKE-3#PBF?

The LTC4381ADKE-3#PBF supports −60V reverse input on the IN pin with no external components. Internally, the GATE drive circuitry and charge pump remain functional during reverse bias, holding the MOSFET fully off and blocking reverse current flow. This eliminates the need for Schottky diodes or back-to-back MOSFET arrangements, reducing forward voltage drop, heat generation, and PCB footprint in battery-powered or dual-supply systems.

What package type and thermal characteristics does LTC4381ADKE-3#PBF use?

The LTC4381ADKE-3#PBF uses a 32-lead plastic DFN package (7mm × 5mm) with exposed thermal pad (Pin 33). Its thermal resistance is θ_JA = 23°C/W, supporting 125°C maximum junction temperature. The exposed pad must be soldered to a thermal plane for effective heat dissipation - especially critical during SOA-limited fault events where 20ms at 70V/1A must be sustained without thermal runaway.