Features and Benefits

  • 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

Product Details

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.

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


  • 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

Product Lifecycle icon-recommended Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Tools & Simulations


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.


Models for the following parts are available in LTspice:


Product Recommendations

LTC4251 Companion Parts

Recommended Related Parts

Design Resources

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.

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The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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