Analog Devices Inc. LT4356HMS-1#TRPBF

Overview

LT4356HMS-1#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) via external N-channel MOSFET gate control. It features 4V–80V operating range, 50mV overcurrent sense threshold, 7µA shutdown current, and guaranteed operation to 125°C - enabling robust protection in automotive and industrial power systems.

For engineers reviewing the LT4356HMS-1#TRPBF datasheet, LT4356HMS-1#TRPBF pinout, LT4356HMS-1#TRPBF application, or LT4356HMS-1#TRPBF equivalent, key selection criteria include its adjustable fault timer, reverse input tolerance to –60V, integrated auxiliary amplifier for undervoltage detection, and MSOP-10 package suitability for space-constrained hot-swap and battery-powered designs.

Technical Context

The LT4356HMS-1#TRPBF implements dual-fault protection: an overvoltage loop servoing the FB pin to 1.25V using a charge-pump-driven GATE output, and an overcurrent loop limiting V_CC–V_SNS to 50mV. Fault timing is dynamically scaled by V_DS (V_CC–V_OUT) to align with MOSFET safe operating area (SOA), with TMR pin current ranging from 2µA (0.5V V_DS) to 50µA (75V V_DS) in overvoltage mode.

It integrates a shutdown-controlled low-quiescent-current architecture (7µA in LT4356-1 variant), a 1.25V internal reference for the auxiliary amplifier, and open-collector FLT/EN/AOUT outputs rated to sink 3mA from 80V. The SHDN pin withstands –60V to 100V, supporting reverse-battery and high-side switch configurations without external protection.

Key Specifications

Pinout & Package

LT4356HMS-1#TRPBF is housed in a 10-lead plastic MSOP package (3mm × 3mm), thermally enhanced with exposed pad option (not present in MSOP). Pin functions are fully defined per Analog Devices' Rev. D datasheet and validated for this variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT4356IMS-1#TRPBF, LT4356HMS-1#TRPBF delivers full automotive under-hood reliability; compared with LT4356HDE-1#TRPBF, it trades thermal performance for smaller board area and simplified assembly in MSOP-optimized designs.

Availability

LT4356HMS-1#TRPBF is available at Aetrix Electronics and suitable for automotive load dump protection, hot-swap power supplies, and battery-powered system protection requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LT4356HMS-1#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 industrial, automotive, communications, and healthcare markets.

The LT4356 family is designed as high-voltage surge stoppers for mission-critical power path protection - specifically targeting automotive, avionic, and industrial systems needing robust overvoltage/overcurrent response with minimal external components.

FAQ

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

The LT4356HMS-1#TRPBF supports continuous operation from 4V to 80V on the VCC pin. Its absolute maximum rating allows VCC to be pulled down to –60V without damage - making it suitable for reverse-battery conditions in automotive applications. This –60V to 100V tolerance applies also to the SHDN and SNS pins, eliminating need for external protection diodes in most high-side switch configurations.

How does the LT4356HMS-1#TRPBF differ from the LT4356-2 variant?

The LT4356HMS-1#TRPBF is the LT4356-1 variant, meaning its shutdown mode disables all functional blocks and draws only 7µA. In contrast, the LT4356-2 maintains auxiliary amplifier and reference operation during shutdown (60µA IQ), enabling undervoltage monitoring or always-on regulation. The LT4356HMS-1#TRPBF does not retain auxiliary functionality in shutdown - a key distinction for low-power monitoring applications.

Can the LT4356HMS-1#TRPBF drive a logic-level MOSFET at low input voltages?

Yes - the LT4356HMS-1#TRPBF's GATE output delivers ≥4.5V above VOUT at VCC = 4V, sufficient to fully enhance logic-level N-channel MOSFETs. At higher VCC (≥8V), GATE is clamped to VOUT + 14V, supporting standard-threshold devices. This dual-range gate drive ensures reliable MOSFET turn-on across cold-crank (4V) to load-dump (80V) conditions without external level-shifting circuitry.

What is the purpose of the TMR pin, and how is the capacitor value selected?

The TMR pin sets both fault warning time (FLT assertion) and total shutdown delay via an external capacitor to ground. For example, a 6.8µF capacitor yields ~100ms total fault timer during 80V overvoltage (per Figure 1). The TMR current scales with V_DS, so capacitor selection must account for worst-case V_DS and required ride-through time. A minimum 10nF capacitor is required for loop stability, and X7R dielectric is recommended for temperature stability.

Does the LT4356HMS-1#TRPBF provide reverse polarity protection?

The LT4356HMS-1#TRPBF itself does not provide reverse polarity protection, but enables robust implementation via back-to-back N-MOSFETs - replacing lossy Schottky diodes. Its SNS and SHDN pins tolerate –60V, and VCC withstands –60V, allowing direct connection to reversed inputs. When paired with a second N-MOSFET in series (source-to-source), the LT4356HMS-1#TRPBF controls both devices to achieve <100mV forward drop and full reverse blocking - significantly improving efficiency over diode-based solutions.