Analog Devices Inc. LT4356HMS-3#TRPBF

Overview

LT4356HMS-3#TRPBF from Analog Devices is a high-voltage surge stopper IC that protects downstream loads by regulating output voltage during overvoltage transients (e.g., automotive load dump) and limiting current via external N-channel MOSFET control. It operates from 4V to 80V, provides reverse input protection to –60V, features adjustable 1.25V FB threshold, and delivers latchoff fault timer with early warning via FLT pin. Used in automotive power distribution systems requiring AEC-Q100 compliance.

For engineers reviewing the LT4356HMS-3#TRPBF datasheet, LT4356HMS-3#TRPBF pinout, LT4356HMS-3#TRPBF application, or LT4356HMS-3#TRPBF equivalent, key selection criteria include its –40°C to 125°C operating range, 10-lead MSOP package, 50mV overcurrent sense threshold, 7µA shutdown current, and integrated auxiliary amplifier for level detection or linear regulator control.

Technical Context

The LT4356HMS-3#TRPBF implements dual-fault protection using independent voltage and current amplifiers: the FB amplifier servo-regulates GATE to maintain 1.25V at FB during overvoltage, while the SNS amplifier limits V_CC–V_SNS to 50mV during overcurrent. Fault timing is dynamically scaled by (V_CC–V_OUT) to match MOSFET safe operating area constraints.

Its SHDN pin withstands –60V to 100V, enabling direct connection to battery rails; the GATE driver delivers up to 150mA pull-down current for fast MOSFET turn-off, and the TMR pin charges with variable current (2µA to 260µA) depending on fault type and V_DS, ensuring adaptive response to transient severity.

Key Specifications

Pinout & Package

LT4356HMS-3#TRPBF is housed in a 10-lead plastic MSOP package (3mm × 3mm), thermally enhanced with exposed pad (optional GND connection). Pin count and layout match industry-standard MSOP footprint for drop-in compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC4365IMS-3#TRPBF and TPS26631PWPR, LT4356HMS-3#TRPBF uniquely supports user-defined output clamping via FB divider, adaptive fault timing matched to MOSFET SOA, and –60V reverse input capability - making it the only option for AEC-Q100-compliant, high-reliability automotive load dump protection with flexible design margins.

Availability

LT4356HMS-3#TRPBF is available at Aetrix Electronics and suitable for automotive power distribution, industrial hot-swap subsystems, and battery-powered medical equipment requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for LT4356HMS-3#TRPBF 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and automotive safety markets.

The LT4356 family was designed specifically for high-reliability automotive and avionic power protection, delivering robust surge suppression, adaptive fault timing, and integrated diagnostics in compact packages compliant with AEC-Q100 Grade H.

FAQ

What is the maximum reverse input voltage the LT4356HMS-3#TRPBF can withstand?

The LT4356HMS-3#TRPBF supports reverse input voltages down to –60V on VCC, SNS, and SHDN pins without damage. This allows direct connection to reversed-battery inputs in automotive and portable systems. The specification is validated across the full –40°C to +125°C operating range and is part of its AEC-Q100 qualification. No external protection diodes are required for this level of reverse polarity immunity in the LT4356HMS-3#TRPBF design.

How does the LT4356HMS-3#TRPBF implement adaptive fault timing?

The LT4356HMS-3#TRPBF implements adaptive fault timing by generating a TMR charging current proportional to (V_CC–V_OUT). During overvoltage, current scales from 2µA (at 0.5V V_DS) to 50µA (at 75V V_DS); during overcurrent, it scales from 4µA to 260µA (at 80V V_DS). This ensures shorter fault timeouts under high-stress conditions, keeping the external MOSFET within its safe operating area. The LT4356HMS-3#TRPBF uses this mechanism to avoid thermal runaway during sustained transients.

Can the LT4356HMS-3#TRPBF drive logic-level MOSFETs at low supply voltages?

Yes - the LT4356HMS-3#TRPBF guarantees GATE drive of ≥4.5V above OUT when V_CC ≥4V, enabling reliable turn-on of logic-level N-channel MOSFETs during cold-crank conditions (e.g., 5V battery). At V_CC ≥8V, GATE swing increases to 10V–16V, supporting standard-threshold devices. This dual-range gate drive is built into the LT4356HMS-3#TRPBF's charge pump architecture and is specified across temperature.

What is the function of the auxiliary amplifier in the LT4356HMS-3#TRPBF?

The auxiliary amplifier in the LT4356HMS-3#TRPBF consists of IN+ and AOUT pins, with its negative input internally tied to a 1.25V reference. It can be configured as a voltage detection comparator (e.g., battery undervoltage monitor) or as a linear regulator controller driving an external PNP pass transistor. Its open-collector AOUT sinks up to 2mA, allowing direct LED or optocoupler interfacing without additional components - a feature unique to the LT4356HMS-3#TRPBF among surge stoppers.

How is latchoff recovery performed on the LT4356HMS-3#TRPBF after a fault timeout?

Latchoff recovery on the LT4356HMS-3#TRPBF requires pulsing the SHDN pin: pull SHDN low for ≥100µs, then raise it above 2.1V with a slew rate >10V/ms. This sequence resets the internal GATE latch and re-enables MOSFET conduction. The LT4356HMS-3#TRPBF does not auto-recover - intentional reset prevents unsafe re-engagement during persistent overvoltage or short-circuit conditions.