LTC4251

RECOMMENDED FOR NEW DESIGNS

Negative Voltage Hot Swap Controllers in SOT-23

Part Models: 13
1ku List Price: Starting From $2.43

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Overview

Allows Safe Board Insertion and Removal from a Live –48V Backplane
Floating Topology Permits Very High Voltage Operation
Low Profile (1mm) ThinSOT^™ Package
Programmable Analog Current Limit with Circuit Breaker Timer

Fast Response Time Limits Peak Fault Current
Programmable Timer
Programmable Undervoltage/Overvoltage Protection

The LTC4251/LTC4251-1/LTC4251-2 negative voltage Hot Swap^™ controllers allow a board to be safely inserted and removed from a live backplane. Output current is controlled by three stages of current limiting: a timed circuit breaker, active current limiting and a fast feed forward path that limits peak current under worst-case catastrophic fault conditions.

Programmable undervoltage and overvoltage detectors disconnect the load whenever the input supply exceeds the desired operating range. The supply input is shunt regulated, allowing safe operation with very high supply voltages. A multifunction timer delays initial start-up and controls the circuit breaker’s response time.

The LTC4251 UV/OV thresholds are designed to match the standard telecom operating range of –43V to –75V. The LTC4251-1 UV/OV thresholds extend the operating range to encompass –36V to –72V. The LTC4251-2 implements a UV threshold of –43V only.

	UV/OV
LTC4251	-43V / -75V
LTC4251-1	-36V / -72V
LTC4251-2	-43V UV Only
LTC4251B	-43V / -75V
LTC4251B-1	-36V / -72V
LTC4251B-2	-43V UV Only

Applications

Hot Board Insertion
Electronic Circuit Breaker
–48V Distributed Power Systems
Negative Power Supply Control
Central Office Switching
Programmable Current Limiting Circuit
High Availability Servers
Disk Arrays

Part Models: 13
1ku List Price: Starting From $2.43

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LTC4251-1CS6#TRMPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251-1CS6#TRPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251-1IS6#TRMPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251-1IS6#TRPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251-2CS6#TRMPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251-2CS6#TRPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251-2IS6#TRMPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251-2IS6#TRPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251CS6#TRM	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251CS6#TRMPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251CS6#TRPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251IS6#TRMPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC4251IS6#TRPBF	6-Lead TSOT-23	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

May 21, 2025 - 25_0033 Carsem SnPb Packaging End of Life
		PDN25_0033_Form Material_Report
LTC4251CS6#TRM	LAST TIME BUY	PDN25_0033_Form Material_Report
May 24, 2021 - 20_0074 Discontinuation of Sn/Pb Plated Lead Finish Parts for S5, S6, TS8 Packages
		PDN20_0074_Form Material_Report
LTC4251CS6#TRM	LAST TIME BUY	PDN20_0074_Form Material_Report

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Protection Switches & Controllers 2
LTC4252 LTC4252A		Negative Voltage Hot Swap Controllers
LT4250		Negative 48V Hot Swap Controller

Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

LTC4251
LTC4251-1
LTC4251-2

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

Latest Discussions

2 Years Ago

LTC4251

Overview

Documentation

Data Sheet 1

Reliability Data 1

Technical Articles 1

Product Selector Card 1