Analog Devices Inc. LT4363IMS-2#PBF

Overview

LT4363IMS-2#PBF from Analog Devices is a high-voltage surge stopper IC that controls an external N-channel MOSFET to regulate output voltage during transients up to 150V, limit current via 50mV SNS–OUT sense threshold, and provide adjustable UV/OV protection with 1.275V comparator thresholds. It operates from 4V to 80V input, delivers <1% retry duty cycle in fault recovery (LT4363-2), and supports hot-swap and avionic power rail protection.

For engineers reviewing the LT4363IMS-2#PBF datasheet, LT4363IMS-2#PBF pinout, LT4363IMS-2#PBF application, or LT4363IMS-2#PBF equivalent, key selection considerations include its 12-lead MSOP package, -40°C to +85°C temperature grade, automatic restart behavior after cool-down, and precise 50mV overcurrent sensing with foldback to 25mV at low OUT.

Technical Context

The LT4363IMS-2#PBF implements dual independent fault detection: overvoltage regulation via FB servo loop maintaining 1.275V at feedback pin, and overcurrent limiting via active amplifier holding ΔVSNS = 50mV (or 25mV when OUT < 2V). Its fault timer uses VCC–OUT–derived current to dynamically scale timing based on MOSFET stress, enabling SOA-optimized protection.

Unlike the latch-off LT4363-1 variant, the LT4363IMS-2#PBF integrates OV comparator input (pin 11) that inhibits retry while OV > 1.275V, preventing oscillation during sustained overvoltage. Its GATE driver delivers 13V above OUT with 14V clamp, and SHDN pin tolerates –60V to +100V with <7µA shutdown current.

Key Specifications

Pinout & Package

LT4363IMS-2#PBF is housed in a 12-lead plastic MSOP package (4.0mm × 3.0mm × 1.1mm) with exposed thermal pad connected to GND. Pin 1 is FB; pin 12 is SHDN. The package supports standard reflow profiles and provides θJA = 135°C/W thermal resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC4365IMS-2#PBF and TPS26631RGER, the LT4363IMS-2#PBF offers unique adjustability of output clamp voltage via FB divider, VDS-scaled fault timing for MOSFET SOA optimization, and –60V reverse input tolerance-making it the only option qualified for harsh avionic and intrinsic safety use cases requiring both programmability and ruggedness.

Availability

LT4363IMS-2#PBF is available at Aetrix Electronics and suitable for avionic power rail protection, industrial hot-swap modules, high-side battery switches, and intrinsic safety barriers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LT4363IMS-2#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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and aerospace markets.

The LT4363 product line was designed specifically for high-reliability power path protection in mission-critical systems-enabling robust surge suppression, precise current limiting, and intelligent fault recovery without microcontroller intervention.

FAQ

What is the maximum input voltage the LT4363IMS-2#PBF can withstand without damage?

The LT4363IMS-2#PBF has an absolute maximum VCC rating of 100V and can survive reverse input conditions down to –60V. Its normal operating range is 4V to 80V, and it is rated to withstand transient surges exceeding 150V when used with appropriate external clamping and MOSFET SOA derating. This makes LT4363IMS-2#PBF suitable for automotive load-dump and avionic surge environments per DO-160 Section 22.

How does the LT4363IMS-2#PBF differ from the LT4363-1 version?

The LT4363IMS-2#PBF implements automatic restart after fault cool-down (TMR discharge to 0.5V), whereas the LT4363-1 latches off permanently until manually reset via SHDN. Additionally, LT4363IMS-2#PBF includes the OV pin (pin 11) to inhibit retry during sustained overvoltage, a feature absent in LT4363-1. Both share identical pinout, package, and core protection functions.

Can the LT4363IMS-2#PBF be used with P-channel MOSFETs?

No-the LT4363IMS-2#PBF is designed exclusively for N-channel MOSFETs configured as high-side switches, leveraging its charge pump to drive GATE above OUT. It does not support P-channel configurations, which require gate drive referenced to input rather than source. Using a P-MOSFET would violate the GATE drive architecture and render FB regulation and current sensing inoperable.

What is the purpose of the ENOUT pin on the LT4363IMS-2#PBF?

The ENOUT pin on the LT4363IMS-2#PBF is an open-collector enable output that goes high-impedance when the external MOSFET is fully enhanced-i.e., when OUT is within 0.5V of VCC and ≥3V above GND. It remains latched in that state until OUT drops below 2V, providing a reliable "power good" signal for system monitoring or sequencing logic without additional components.

How is overcurrent protection implemented in the LT4363IMS-2#PBF?

The LT4363IMS-2#PBF implements overcurrent protection by regulating the voltage between SNS and OUT pins to 50mV under normal conditions. When OUT falls below 2V (e.g., during output short), the threshold folds back to 25mV to reduce MOSFET power dissipation. An internal amplifier controls GATE to maintain this sense voltage, and the resulting ΔVSNS error drives the TMR capacitor with ~5× higher current than in overvoltage mode for faster fault response.