Analog Devices Inc. LT4356HS-2#PBF

Overview

LT4356HS-2#PBF from Analog Devices is a high-voltage surge stopper IC that protects downstream loads by regulating output 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, 1.25V FB reference, and −40°C to +125°C extended temperature rating in 16-pin SO package.

For engineers reviewing the LT4356HS-2#PBF datasheet, LT4356HS-2#PBF pinout, LT4356HS-2#PBF application, or LT4356HS-2#PBF equivalent, key selection criteria include adjustable fault timer response, reverse input protection to −60V, auxiliary amplifier functionality during shutdown, and guaranteed operation at 125°C for under-hood automotive systems.

Technical Context

The LT4356HS-2#PBF implements dual-fault protection using independent voltage and current amplifiers: the voltage amplifier servo-controls the GATE pin to clamp VOUT via FB feedback, while the current amplifier limits ΔVSNS = VCC − VSNS to 50mV. Fault timing is dynamically scaled with VDS (VCC − VOUT), enabling adaptive MOSFET safe operating area (SOA) management across 0.5V–75V differential.

Unlike the LT4356-1 variant, the LT4356HS-2#PBF maintains its auxiliary amplifier active during shutdown (60µA quiescent current), supporting undervoltage lockout or always-on linear regulation via external PNP transistor - critical for fail-safe power sequencing in industrial and avionic systems.

Key Specifications

Pinout & Package

LT4356HS-2#PBF is housed in a 16-lead plastic SO package (JEDEC MS-012) with exposed thermal pad option (not applicable to SO). Pin 1 is top-left corner; pin numbering proceeds counter-clockwise. The package supports reflow soldering up to 300°C for 10 seconds and has θJA = 100°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT4356HS-1#PBF and TPS26631PWPR, the LT4356HS-2#PBF uniquely combines extended temperature operation, active auxiliary amplifier during shutdown, and VDS-scaled fault timing - making it optimal for safety-critical automotive and avionic power conditioning where reliability and design flexibility are paramount.

Availability

LT4356HS-2#PBF is available at Aetrix Electronics and suitable for automotive load dump protection, industrial hot-swap distribution, and avionic power sequencing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LT4356HS-2#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 systems - specifically targeting automotive, avionic, and industrial applications demanding robust overvoltage/overcurrent protection with precise regulation and fail-safe behavior.

FAQ

What is the maximum reverse voltage the LT4356HS-2#PBF can withstand on its VCC pin?

The LT4356HS-2#PBF supports −60V on the VCC pin without damage, enabling direct integration into reverse-battery protected automotive systems without additional external components. This rating applies across the full −40°C to +125°C operating temperature range and is verified per Absolute Maximum Ratings in the datasheet.

How does the LT4356HS-2#PBF differ from the LT4356HS-1#PBF in shutdown mode?

In shutdown mode, the LT4356HS-2#PBF draws 60µA while keeping the auxiliary amplifier and internal 1.25V reference active - enabling continuous UVLO monitoring or bias generation. In contrast, the LT4356HS-1#PBF draws only 7µA but disables the auxiliary amplifier entirely during shutdown.

Can the LT4356HS-2#PBF regulate output voltage to a specific value like 27V?

Yes - the LT4356HS-2#PBF regulates output by servoing the FB pin to 1.25V. Using an external resistor divider between OUT and GND, users can set any output clamp voltage; for example, a 27V clamp requires R1/R2 = 21.6 per the standard formula VOUT = 1.25V × (1 + R1/R2).

What MOSFET parameters are critical when selecting an external pass device for the LT4356HS-2#PBF?

Critical MOSFET parameters include logic-level gate threshold (for reliable turn-on at low VCC), SOA rating covering simultaneous high VDS and ID during faults, and RDS(on) low enough to minimize conduction loss at full load. The LT4356HS-2#PBF's VDS-scaled timer ensures the MOSFET operates within its SOA envelope.

Does the LT4356HS-2#PBF provide overcurrent protection independent of overvoltage events?

Yes - the LT4356HS-2#PBF implements independent overcurrent protection by regulating ΔVSNS = VCC − VSNS to 50mV. This triggers its own fault timer path with higher current injection into the TMR pin (up to 260µA), resulting in faster shutdown than overvoltage events - ensuring rapid response to short circuits.