Analog Devices Inc. LT4356HDE-2#TRPBF

Overview

LT4356HDE-2#TRPBF from Analog Devices is a high-voltage surge stopper IC that regulates output during overvoltage transients (e.g., automotive load dump) by controlling an external N-channel MOSFET gate. It provides adjustable 1.25V FB-clamped output regulation, 50mV overcurrent sensing threshold, and operates across 4V–80V input with –40°C to 125°C extended temperature rating. Used in automotive power protection circuits where continuous operation under transient stress is required.

For engineers reviewing the LT4356HDE-2#TRPBF datasheet, LT4356HDE-2#TRPBF pinout, LT4356HDE-2#TRPBF application, or LT4356HDE-2#TRPBF equivalent, key selection criteria include its 60µA shutdown current (vs. 7µA in -1 variant), active auxiliary amplifier during shutdown, 12-lead 4mm × 3mm DFN package, and guaranteed operation up to 125°C for under-hood automotive use.

Technical Context

The LT4356HDE-2#TRPBF implements dual-loop protection: a voltage amplifier servoing the GATE pin to maintain 1.25V at FB during overvoltage, and a current amplifier limiting V_CC–V_SNS to 50mV during overcurrent. Its fault timer current scales with V_DS (up to 50µA in OV, 260µA in OC), enabling dynamic SOA-aware MOSFET stress management.

Unlike the LT4356-1 variant, the LT4356HDE-2#TRPBF retains auxiliary amplifier functionality and internal 1.25V reference during shutdown, supporting undervoltage lockout or always-on regulator control. Its SHDN pin withstands –60V to 100V and features TTL-compatible thresholds with 100µs low-pulse requirement for reliable entry/exit.

Key Specifications

Pinout & Package

LT4356HDE-2#TRPBF uses a 12-lead (4mm × 3mm) plastic DFN package with exposed pad (Pin 13), rated for operation up to 125°C. The exposed pad may be left unconnected or tied to GND for improved thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT4356HDE-1#TRPBF, the LT4356HDE-2#TRPBF trades 53µA higher shutdown current for retained auxiliary functionality - essential for safety-critical monitoring. Versus TPS26631RTJR, it offers field-programmable OV clamping, scalable current limiting, and SOA-aware fault timing, at the cost of external MOSFET and layout complexity.

Availability

LT4356HDE-2#TRPBF is available at Aetrix Electronics and suitable for automotive load dump protection, industrial hot-swap power entry, and intrinsic safety barrier power requiring stable component supply across extended temperature ranges.

Supply support for LT4356HDE-2#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 markets.

The LT4356 family is designed as a high-voltage surge stopper IC for protecting downstream loads from automotive load dump, industrial transients, and overcurrent faults - emphasizing robustness, SOA-aware fault handling, and extended temperature operation.

FAQ

What is the key functional difference between LT4356HDE-2#TRPBF and LT4356HDE-1#TRPBF?

The LT4356HDE-2#TRPBF maintains its auxiliary amplifier and internal 1.25V reference active during shutdown, enabling undervoltage lockout or always-on regulator control. In contrast, the LT4356HDE-1#TRPBF disables all functional blocks in shutdown, achieving lower 7µA quiescent current but losing monitoring capability. Both share identical overvoltage regulation, overcurrent protection, and pinout.

How does the fault timer in LT4356HDE-2#TRPBF adapt to different MOSFET stress levels?

The LT4356HDE-2#TRPBF's TMR pin current scales with V_DS (V_CC–V_OUT): from ~2µA at 0.5V to 50µA at 75V during overvoltage, and up to 260µA during overcurrent. This ensures shorter fault timer periods under high-voltage/high-current stress, keeping the external MOSFET within its safe operating area without requiring manual timer adjustment per application.

Can LT4356HDE-2#TRPBF drive logic-level N-channel MOSFETs at low input voltages?

Yes - the LT4356HDE-2#TRPBF's GATE pin delivers ≥4.5V above V_OUT when V_CC = 4V, sufficient to fully enhance logic-level N-MOSFETs. At higher V_CC, the internal clamp limits GATE to V_OUT + 14V, preventing gate oxide overstress. This dual-range drive supports cold-crank operation while protecting standard MOSFETs.

What is the maximum reverse voltage LT4356HDE-2#TRPBF can withstand on its VCC and SNS pins?

The LT4356HDE-2#TRPBF tolerates –60V on both VCC and SNS pins relative to GND. However, the voltage difference between VCC and SNS must remain ≤30V. This allows direct connection to reverse-battery automotive systems without external protection diodes, simplifying front-end design and improving reliability.

Does LT4356HDE-2#TRPBF require external components to implement overvoltage regulation?

Yes - LT4356HDE-2#TRPBF requires an external resistive divider from OUT to GND to set the FB voltage and thus the regulated output clamp level. A minimum 10nF ceramic capacitor on TMR is also mandatory for loop stability. No external op-amps or references are needed, as the 1.25V reference and amplifiers are integrated.