Analog Devices Inc. LT4356HDE-1#PBF

Overview

LT4356HDE-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 extended temperature rating, 7µA shutdown current, and integrated overcurrent protection with 50mV current sense threshold.

For engineers reviewing the LT4356HDE-1#PBF datasheet, LT4356HDE-1#PBF pinout, LT4356HDE-1#PBF application, or LT4356HDE-1#PBF equivalent, key selection criteria include fault timer adjustability, reverse input tolerance (–60V), GATE drive capability (14V above OUT), auxiliary amplifier availability, and DFN-12 package thermal performance for high-reliability industrial and automotive power systems.

Technical Context

The LT4356HDE-1#PBF implements dual-loop protection: a voltage amplifier servoing the FB pin to 1.25V during overvoltage events, and a current amplifier limiting ΔVSNS to 50mV during overcurrent faults. Both loops feed a programmable fault timer (TMR pin) whose charging current scales with V_DS (VCC–OUT) to dynamically match MOSFET safe operating area (SOA).

It integrates a charge pump enabling full enhancement of standard N-channel MOSFETs at low VCC (≥4V), supports back-to-back FET reverse polarity protection, and provides independent shutdown control (SHDN) with –60V to 100V tolerance. The H-grade variant guarantees operation up to 125°C junction temperature with θ_JA = 43°C/W in the 4mm × 3mm DFN package.

Key Specifications

Pinout & Package

LT4356HDE-1#PBF is housed in a thermally enhanced 12-lead (4mm × 3mm) plastic DFN package with exposed pad (Pin 13), rated for TJ_MAX = 125°C and θ_JA = 43°C/W. The exposed pad may be left unconnected or tied to PCB ground for improved thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC4365IDDB#TRPBF and TPS26631PWPR, LT4356HDE-1#PBF uniquely supports 80V operation, programmable output clamping, V_DS-adaptive fault timing, and an auxiliary amplifier - making it the only option qualified for high-reliability, wide-range, and functionally flexible surge protection in extended temperature environments.

Availability

LT4356HDE-1#PBF is available at Aetrix Electronics and suitable for automotive load dump protection, industrial hot-swap power supplies, intrinsic safety barriers, and avionic power conditioning requiring stable component supply across extended temperature ranges.

Supply support for LT4356HDE-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, Inc. 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, emphasizing robustness, adaptability to MOSFET SOA, and integration of auxiliary functions like level detection and linear regulation control.

FAQ

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

The absolute maximum voltage difference between VCC and SNS pins is 30V, as specified in the Absolute Maximum Ratings table. This constraint applies regardless of whether SNS is pulled below ground - SNS may go as low as –60V, but only if VCC is ≥ –30V. Exceeding this differential risks permanent damage to the internal current sense amplifier in the LT4356HDE-1#PBF.

Can the LT4356HDE-1#PBF be used with a P-channel MOSFET instead of an N-channel device?

No - the LT4356HDE-1#PBF is specifically architected to drive N-channel MOSFETs configured as high-side switches, leveraging its charge pump and GATE clamp referenced to OUT. It does not provide the negative gate drive or level-shifting required for efficient P-channel operation. Using a P-FET would disable overvoltage regulation, violate timing assumptions, and void the protection guarantees of the LT4356HDE-1#PBF.

How does the LT4356HDE-1#PBF handle reverse battery conditions?

The LT4356HDE-1#PBF tolerates –60V on VCC, SHDN, and SNS pins without damage, enabling direct connection to automotive battery inputs. During reverse polarity, internal protection structures block conduction while maintaining latch-up immunity. When paired with back-to-back N-FETs (instead of a Schottky diode), the LT4356HDE-1#PBF enables true bidirectional reverse protection with near-zero forward voltage drop - a key advantage over diode-based solutions.

Is the auxiliary amplifier in the LT4356HDE-1#PBF functional during shutdown mode?

No - the LT4356HDE-1#PBF is the -1 variant, which disables all functional blocks including the auxiliary amplifier during shutdown. Only the LT4356-2 variants (e.g., LT4356HDE-2#PBF) retain auxiliary amplifier operation and internal reference in shutdown. In LT4356HDE-1#PBF, pulling SHDN low reduces total supply current to ≤7µA and halts AOUT/IN+ functionality entirely.

What is the minimum recommended value for the TMR capacitor in the LT4356HDE-1#PBF?

Analog Devices specifies a minimum TMR capacitor value of 10nF for loop stability, as stated in the PIN FUNCTIONS section. This value ensures adequate phase margin for the regulation loop during both overvoltage and overcurrent events. Using less than 10nF may cause oscillation in the GATE drive or erratic FLT assertion, compromising protection integrity in the LT4356HDE-1#PBF.