Analog Devices Inc. LT4356HMS-1#PBF

Overview

LT4356HMS-1#PBF 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) via external N-channel MOSFET gate control. It features 4V–80V operating range, –40°C to 125°C temperature grade, 50mV overcurrent sense threshold, and 7µA shutdown current. Used in automotive power distribution systems requiring robust transient immunity.

For engineers reviewing the LT4356HMS-1#PBF datasheet, LT4356HMS-1#PBF pinout, LT4356HMS-1#PBF application, or LT4356HMS-1#PBF equivalent, key selection criteria include its adjustable output clamp voltage, fault timer scalability with V_DS, reverse input protection to –60V, and compatibility with back-to-back FET configurations for low-loss reverse polarity blocking.

Technical Context

The LT4356HMS-1#PBF implements dual-loop protection: a voltage amplifier servoing the FB pin to 1.25V during overvoltage events, and a current amplifier limiting ΔV_SNS = V_CC – V_SNS to 50mV during overcurrent faults. Its GATE driver uses an internal charge pump to deliver up to 150mA pull-down current and supports V_GATE up to V_OUT + 14V.

Fault timing is dynamically scaled by V_DS (V_CC – V_OUT): overvoltage timer current ranges from 2µA (0.5V) to 50µA (75V), while overcurrent timer current scales from 4µA to 260µA (80V). The FLT pin asserts at VTMR = 1.25V for early warning; GATE turns off at VTMR = 1.35V after a cool-down period resets at VTMR = 0.5V.

Key Specifications

Pinout & Package

LT4356HMS-1#PBF is housed in a 10-lead plastic MSOP package (3mm × 3mm), rated for operation up to 125°C ambient. Exposed pad is not present in MSOP variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC4365IMS-1#PBF and TPS26631PWPR, LT4356HMS-1#PBF uniquely supports 80V operation, –60V reverse input, V_DS-adaptive fault timing, and an auxiliary amplifier-making it the only option qualified for under-hood automotive surge suppression with design flexibility.

Availability

LT4356HMS-1#PBF is available at Aetrix Electronics and suitable for automotive power distribution, industrial hot-swap subsystems, and intrinsic safety barrier designs requiring stable component supply across extended temperature and voltage extremes.

Supply support for LT4356HMS-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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets.

The LT4356 family was designed specifically for high-reliability power path protection in harsh environments-emphasizing wide input voltage range, robust fault handling, and integration of auxiliary functions like level detection and linear regulation control.

FAQ

What is the maximum input voltage the LT4356HMS-1#PBF can withstand continuously?

The LT4356HMS-1#PBF operates continuously from 4V to 80V on the VCC pin. Its absolute maximum rating allows VCC to reach 100V transiently, but sustained operation above 80V risks permanent damage. Reverse input tolerance extends to –60V on SHDN and SNS pins, enabling direct connection to battery rails with polarity reversal risk.

How does the LT4356HMS-1#PBF implement overcurrent protection?

The LT4356HMS-1#PBF monitors voltage drop between VCC and SNS pins, limiting ΔV_SNS to 50mV via GATE servo control. This corresponds to a precise current limit determined by the external sense resistor value. During sustained overcurrent, the TMR pin charges at a rate scaled by V_DS, triggering FLT at 1.25V and turning off the MOSFET at 1.35V.

Can the LT4356HMS-1#PBF be used with P-channel MOSFETs?

No-the LT4356HMS-1#PBF is designed exclusively for N-channel MOSFETs configured as high-side switches. Its GATE driver architecture relies on charge-pump boosting relative to the OUT (source) node. Driving a P-channel device would require inverted logic and different gate voltage referencing, which the LT4356HMS-1#PBF does not support.

What is the purpose of the auxiliary amplifier in the LT4356HMS-1#PBF?

The auxiliary amplifier in the LT4356HMS-1#PBF has its negative input tied to an internal 1.25V reference and offers open-collector output (AOUT) capable of sinking 2mA. It can be configured as a voltage detection comparator (e.g., undervoltage lockout using IN+) or as a linear regulator controller driving an external PNP pass transistor for auxiliary bias supplies.

Does the LT4356HMS-1#PBF support reverse polarity protection without external components?

The LT4356HMS-1#PBF itself does not provide active reverse polarity protection, but its SHDN and SNS pins tolerate –60V, and it supports back-to-back N-channel MOSFET configurations that replace Schottky diodes. When implemented with two matched N-MOSFETs, this topology achieves <10mV forward drop and full reverse blocking-eliminating diode losses and heat generation.