Analog Devices Inc. LT4363HS-1#PBF

Overview

LT4363HS-1#PBF from Analog Devices is a high-voltage surge stopper IC that controls an external N-channel MOSFET to regulate output voltage during overvoltage transients up to 150V, limits current via 50mV SNS–OUT sense threshold, and features latch-off fault behavior with 1.275V FB reference and –40°C to 125°C operating range. It enables uninterrupted operation in avionic power systems during 100V+ surges.

For engineers reviewing the LT4363HS-1#PBF datasheet, LT4363HS-1#PBF pinout, LT4363HS-1#PBF application, or LT4363HS-1#PBF equivalent, key selection considerations include its 16-pin SO package, UV/OV comparator thresholds (1.275V), adjustable fault timer via TMR capacitor, 7µA shutdown current, and latch-off (non-retry) response to overvoltage/overcurrent faults.

Technical Context

The LT4363HS-1#PBF implements dual independent protection loops: a voltage servo loop using FB feedback to clamp output at 27V (via external resistor divider) during input surges, and a current-limit loop regulating ΔVSNS to 50mV (or 25mV if OUT < 2V). Its fault timer uses VCC–OUT–derived current to dynamically scale timing with MOSFET stress.

It integrates precision UV (1.275V) and OV (1.275V, LT4363-2 only) comparators, but LT4363HS-1#PBF omits the OV pin-confirmed by SO package pinout showing NC at pin 15-and latches off permanently after fault timeout, requiring SHDN reset. Gate drive delivers up to 13V above OUT with 14V clamp and ±100mA pull-down capability.

Key Specifications

Pinout & Package

LT4363HS-1#PBF is housed in a 16-lead plastic SO package (S package) with exposed thermal pad not present; pin 1 is OUT, pin 16 is GND. Maximum junction temperature is 125°C; θJA = 80°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT4363HS-2#PBF, LT4363HS-1#PBF eliminates motorboating risk in sustained overvoltage by latching off, while LT4363IMS-1#PBF trades thermal performance for smaller footprint-both retain identical protection thresholds and timing architecture.

Availability

LT4363HS-1#PBF is available at Aetrix Electronics and suitable for avionic power distribution, industrial hot-swap modules, intrinsic safety barriers, and battery-powered medical equipment requiring stable component supply across extended temperature ranges.

Supply support for LT4363HS-1#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 company specializing in high-performance analog, mixed-signal, and digital signal processing technologies.

The LT4363 product line delivers robust front-end protection for high-reliability power systems, designed specifically for avionics, industrial automation, and safety-critical infrastructure where surge resilience and deterministic fault response are mandatory.

FAQ

What is the function of the TMR pin on the LT4363HS-1#PBF?

The TMR pin on the LT4363HS-1#PBF accepts an external capacitor to set the fault timer duration. During overvoltage or overcurrent faults, current proportional to VCC–OUT charges this capacitor. At 1.275V, FLT pulls low for early warning; at 1.375V, the MOSFET turns off permanently. The capacitor also determines cool-down time before reset is possible. LT4363HS-1#PBF requires SHDN reset after fault timeout.

Does the LT4363HS-1#PBF support automatic restart after a fault?

No, the LT4363HS-1#PBF implements latch-off behavior: once the MOSFET turns off due to overvoltage or overcurrent, both GATE and FLT remain low indefinitely. Recovery requires a deliberate SHDN pin pulse (≤0.4V for ≥100µs), followed by release to allow internal logic reset. This ensures deterministic shutdown for safety-critical applications where uncontrolled retries are unacceptable.

How does the LT4363HS-1#PBF handle reverse input voltage conditions?

The LT4363HS-1#PBF withstands reverse input voltages down to –60V on VCC, SHDN, UV, and OV pins without damage or functional degradation. Its internal protection circuitry blocks reverse current flow and maintains latch-off state integrity. This capability eliminates the need for external reverse-polarity diodes in battery-powered or vehicle-mounted systems where accidental reverse connection may occur.

What is the purpose of the ENOUT pin on the LT4363HS-1#PBF?

The ENOUT pin on the LT4363HS-1#PBF is an open-collector enable output that signals MOSFET conduction status. It goes high-impedance when VOUT is within 0.5V of VCC and ≥3V above GND-indicating the external N-MOSFET is fully enhanced. The state latches until VOUT drops below 2V. This pin allows system-level monitoring of power path readiness without additional sensing circuitry, simplifying diagnostics in LT4363HS-1#PBF-based designs.

Can the LT4363HS-1#PBF be used with back-to-back MOSFETs for reverse input protection?

Yes, the LT4363HS-1#PBF supports back-to-back N-channel MOSFET configurations for bidirectional reverse-input protection. By driving both gates synchronously, it eliminates the 0.3V–0.5V forward drop of Schottky diodes, improving efficiency and available output voltage. The device's –60V reverse tolerance on control pins ensures reliable gate drive under reverse-battery conditions, making LT4363HS-1#PBF ideal for automotive and portable equipment where power loss and heat must be minimized.