Analog Devices Inc. LT4356HDE-1#TRPBF

Overview

LT4356HDE-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, –40°C to 125°C extended temperature rating, 50mV overcurrent sense threshold, and 7µA shutdown current. Used in automotive power distribution systems requiring robust transient immunity.

For engineers reviewing the LT4356HDE-1#TRPBF datasheet, LT4356HDE-1#TRPBF pinout, LT4356HDE-1#TRPBF application, or LT4356HDE-1#TRPBF equivalent, key selection criteria include fault timer adjustability, reverse input protection to –60V, GATE drive capability up to 14V above OUT, and guaranteed operation at 125°C junction temperature.

Technical Context

The LT4356HDE-1#TRPBF implements dual-fault protection: overvoltage regulation via FB-servo loop maintaining 1.25V at feedback pin, and overcurrent limiting by clamping V_CC–V_SNS to 50mV. Fault detection triggers a voltage-dependent timer (TMR pin) with early warning (FLT low at 1.25V) and shutdown (GATE off at 1.35V).

It integrates an internal charge pump for N-MOSFET gate drive, supports back-to-back FET reverse polarity protection, and includes a shutdown pin tolerant to –60V to 100V. The LT4356-1 variant disables auxiliary amplifier in shutdown, distinguishing it from LT4356-2.

Key Specifications

Pinout & Package

LT4356HDE-1#TRPBF is housed in a 12-lead (4mm × 3mm) plastic DFN package with exposed pad (Pin 13), rated for 125°C maximum junction temperature and θ_JA = 43°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT4356IDE-1#TRPBF and LT4356HMS-1#TRPBF, the LT4356HDE-1#TRPBF uniquely delivers full-featured H-grade operation in the smallest footprint (4mm × 3mm DFN) with both IN+ and AOUT pins enabled-essential for thermally demanding, function-rich surge protection designs.

Availability

LT4356HDE-1#TRPBF is available at Aetrix Electronics and suitable for automotive load dump protection, industrial 24V/48V power rail hardening, and intrinsic safety barrier supply applications requiring stable component supply across extended temperature and high-reliability production cycles.

Supply support for LT4356HDE-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, Inc. 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 high-voltage surge stoppers for protecting sensitive downstream electronics from automotive load dump, hot-swap transients, and reverse-polarity faults-targeting mission-critical power integrity in harsh environments.

FAQ

What is the maximum allowable voltage difference between VCC and SNS pins on the LT4356HDE-1#TRPBF?

The absolute maximum voltage difference between VCC and SNS pins is 30V, as specified in the Absolute Maximum Ratings table. Exceeding this differential risks permanent damage, even if individual pin voltages remain within their respective ranges. This constraint applies regardless of whether SNS is pulled below ground - the LT4356HDE-1#TRPBF allows SNS to go as low as –60V relative to system ground, but only if VCC – SNS ≤ 30V.

Does the LT4356HDE-1#TRPBF support adjustable overvoltage clamp voltage, and how is it set?

Yes, the LT4356HDE-1#TRPBF supports fully adjustable overvoltage clamp voltage via the FB pin. A resistive divider from OUT to GND sets the regulated output: V_OUT = 1.25V × (1 + R1/R2). For example, a 21.5kΩ (R1) and 1kΩ (R2) divider yields a 27V clamp. The FB pin's 1.25V reference has ±1.2% tolerance over temperature, ensuring accurate regulation across the –40°C to 125°C range of the LT4356HDE-1#TRPBF.

How does the fault timer on the LT4356HDE-1#TRPBF respond differently during overvoltage versus overcurrent events?

During overvoltage, TMR charging current scales from ~2µA (at 0.5V V_DS) to 50µA (at 75V V_DS). At FLT assertion (1.25V), it drops to fixed 5µA for a 20ms/µF warning period. During overcurrent, TMR current scales more aggressively - from ~4µA to 260µA - and remains at full value after FLT assertion, yielding faster total shutdown (e.g., 2.86ms/µF warning). This asymmetry prioritizes MOSFET SOA preservation in high-power fault conditions for the LT4356HDE-1#TRPBF.

Can the LT4356HDE-1#TRPBF drive logic-level N-channel MOSFETs at low input voltages?

Yes - the LT4356HDE-1#TRPBF's GATE output delivers ≥4.5V above OUT when VCC = 4V, enabling direct drive of logic-level N-MOSFETs (e.g., IRLR2908) even during automotive cold-crank conditions. At higher VCC (≥8V), GATE reaches up to V_OUT + 14V, ensuring enhancement-mode MOSFETs remain fully enhanced. This dual-range gate drive is intrinsic to the LT4356HDE-1#TRPBF's architecture and requires no external level-shifting.

What is the purpose of the exposed pad (Pin 13) on the LT4356HDE-1#TRPBF DFN package?

The exposed pad on the LT4356HDE-1#TRPBF is electrically connected to GND and serves as the primary thermal path. It may be left unconnected or soldered to a PCB GND plane - doing so reduces θ_JA from 43°C/W to ~30°C/W, directly improving power dissipation capability and junction temperature margin. No voltage or signal is present on this pad; its sole function is thermal management for the LT4356HDE-1#TRPBF in high-stress surge conditions.