LTC4252B/LTC4252C - Negative Voltage Hot Swap Controllers


  • Allows Safe Board Insertion and Removal from a Live –48V Backplane
  • Floating Topology Permits Very High Voltage Operation
  • Current Limit With Circuit Breaker Timer
  • Fast Response Time Limits Peak Fault Current
  • Programmable Soft-Start Current Limit
  • Programmable Timer with Drain Voltage Accelerated Response
  • ±1% Undervoltage/Overvoltage Threshold (LTC4252C)
  • Improved Ruggedness Shunt Regulator
  • Adjustable Undervoltage/Overvoltage Protection
  • LTC4252B-1/LTC4252C-1: Latch Off After Fault
  • LTC4252B-2/LTC4252C-2: Automatic Retry After Fault
  • Available in 8-Pin and 10-Pin MSOP Packages

Typical Application

LTC4252B-1 Typical Application
LTC4252B-1 Typical Application


The LTC®4252 negative voltage Hot SwapTM controller allows 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 feedforward path that limits peak current under worst-case catastrophic fault conditions.

Adjustable undervoltage and overvoltage detectors disconnect the load whenever the input supply exceeds the desired operating range. The LTC4252’s supply input is shunt regulated, allowing safe operation with very high supply voltages. A multifunction timer delays initial startup and controls the circuit breaker’s response time. The circuit breaker’s response time is accelerated by sensing excessive MOSFET drain voltage, keeping the MOSFET within its safe operating area (SOA). An adjustable softstart circuit controls MOSFET inrush current at start-up.

The LTC4252-2 provides automatic retry after a fault. The LTC4252C-1/LTC4252C-2 feature tight ±1% undervoltage/ overvoltage threshold accuracy. The LTC4252 is available in either an 8-pin or 10-pin MSOP.

The LTC4252B and LTC4252C improve the ruggedness of the shunt regulator in the LTC4252 and LTC4252A.

  UV/OV %
Latch Off/Retry Package
LTC4252-1 4.6% Latch off MS-8, MS-10
LTC4252-2 4.8%  Retry MS-8, MS-10
LTC4252A-1 1% Latch off MS-10
LTC4252A-2 1% Retry MS-10
LTC4252B-1 4.6% Latch off MS-8, MS-10
LTC4252B-2 4.6% Retry MS-8, MS-10
LTC4252C-1 1% Latch off MS-10
LTC4252C-2 1% Retry MS-10


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LTC4252BCMS-1#PBF MS-10 MS C 05-08-1661 Yes
LTC4252BCMS-1#TRPBF MS-10 MS C 05-08-1661 Yes
LTC4252BCMS-2#PBF MS-10 MS C 05-08-1661 Yes
LTC4252BCMS-2#TRPBF MS-10 MS C 05-08-1661 Yes
LTC4252BCMS8-1#PBF MS-8 MS8 C 05-08-1660 Yes
LTC4252BCMS8-1#TRPBF MS-8 MS8 C 05-08-1660 Yes
LTC4252BCMS8-2#PBF MS-8 MS8 C 05-08-1660 Yes
LTC4252BCMS8-2#TRPBF MS-8 MS8 C 05-08-1660 Yes
LTC4252BIMS-1#PBF MS-10 MS I 05-08-1661 Yes
LTC4252BIMS-1#TRPBF MS-10 MS I 05-08-1661 Yes
LTC4252BIMS-2#PBF MS-10 MS I 05-08-1661 Yes
LTC4252BIMS-2#TRPBF MS-10 MS I 05-08-1661 Yes
LTC4252BIMS8-1#PBF MS-8 MS8 I 05-08-1660 Yes
LTC4252BIMS8-1#TRPBF MS-8 MS8 I 05-08-1660 Yes
LTC4252BIMS8-2#PBF MS-8 MS8 I 05-08-1660 Yes
LTC4252BIMS8-2#TRPBF MS-8 MS8 I 05-08-1660 Yes
LTC4252CCMS-1#PBF MS-10 MS C 05-08-1661 Yes
LTC4252CCMS-1#TRPBF MS-10 MS C 05-08-1661 Yes
LTC4252CCMS-2#PBF MS-10 MS C 05-08-1661 Yes
LTC4252CCMS-2#TRPBF MS-10 MS C 05-08-1661 Yes
LTC4252CIMS-1#PBF MS-10 MS I 05-08-1661 Yes
LTC4252CIMS-1#TRPBF MS-10 MS I 05-08-1661 Yes
LTC4252CIMS-2#PBF MS-10 MS I 05-08-1661 Yes
LTC4252CIMS-2#TRPBF MS-10 MS I 05-08-1661 Yes

LTC4252B-1 Package Drawing
LTC4252B-1 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LTC4252BCMS-1#PBF MS-10 C $3.00 $2.35 Yes
LTC4252BCMS-1#TRPBF MS-10 C $2.41 Yes
LTC4252BCMS-2#PBF MS-10 C $3.00 $2.35 Yes
LTC4252BCMS-2#TRPBF MS-10 C $2.41 Yes
LTC4252BCMS8-1#PBF MS-8 C $2.55 $2.00 Yes
LTC4252BCMS8-1#TRPBF MS-8 C $2.06 Yes
LTC4252BCMS8-2#PBF MS-8 C $2.55 $2.00 Yes
LTC4252BCMS8-2#TRPBF MS-8 C $2.06 Yes
LTC4252BIMS-1#PBF MS-10 I $3.40 $2.65 Yes
LTC4252BIMS-1#TRPBF MS-10 I $2.71 Yes
LTC4252BIMS-2#PBF MS-10 I $3.40 $2.65 Yes
LTC4252BIMS-2#TRPBF MS-10 I $2.71 Yes
LTC4252BIMS8-1#PBF MS-8 I $2.90 $2.30 Yes
LTC4252BIMS8-1#TRPBF MS-8 I $2.36 Yes
LTC4252BIMS8-2#PBF MS-8 I $2.90 $2.30 Yes
LTC4252BIMS8-2#TRPBF MS-8 I $2.36 Yes
LTC4252CCMS-1#PBF MS-10 C $3.45 $2.50 Yes
LTC4252CCMS-1#TRPBF MS-10 C $2.56 Yes
LTC4252CCMS-2#PBF MS-10 C $3.45 $2.50 Yes
LTC4252CCMS-2#TRPBF MS-10 C $2.56 Yes
LTC4252CIMS-1#PBF MS-10 I $3.90 $2.90 Yes
LTC4252CIMS-1#TRPBF MS-10 I $2.96 Yes
LTC4252CIMS-2#PBF MS-10 I $3.90 $2.90 Yes
LTC4252CIMS-2#TRPBF MS-10 I $2.96 Yes
Buy NowRequest Samples
* 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 Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC787A-A LTC4252CCMS-1 Demoboard | Negative Voltage Hot Swap Controller in an AdvancedTCA Application, Latch Off After Fault $75.00
DC787A-B LTC4252CCMS-2 Demoboard | Negative Voltage Hot Swap Controller in an AdvancedTCA Application, Auto Retry After Fault $75.00
Buy Now
Click here to view our complete list of demo boards


  • Hot Board Insertion
  • Electronic Circuit Breaker
  • –48V Distributed Power Systems
  • Negative Power Supply Control
  • Central Office Switching
  • High Availability Servers
  • ATCA

Product Notifications

Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.

Forgot your password? Click here.
Need help? Email with questions and comments.

Design Tools


LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:

Technical Support