LTC4252/LTC4252A - 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 Accuracy (LTC4252A)
  • Adjustable Undervoltage/Overvoltage Protection
  • LTC4252-1/LTC4252A-1: Latch Off After Fault
  • LTC4252-2/LTC4252A-2: Automatic Retry After Fault
  • Available in 8-Pin and 10-Pin MSOP Packages

Typical Application

LTC4252-1 Typical Application
LTC4252-1 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 LTC4252-1/LTC4252A-1 latch off after a circuit breaker fault times out. The LTC4252-2/LTC4252A-2 provide automatic retry after a fault. The LTC4252A-1/LTC4252A-2 feature tight ±1% undervoltage/overvoltage threshold accuracy. The LTC4252 is available in either an 8-pin or 10-pin MSOP, while the LTC4252A is available in the 10-pin MSOP.

  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
LTC4252-1CMS#PBF MS-10 MS C 05-08-1661 Yes
LTC4252-1CMS#TRPBF MS-10 MS C 05-08-1661 Yes
LTC4252-1CMS8#PBF MS-8 MS8 C 05-08-1660 Yes
LTC4252-1CMS8#TRPBF MS-8 MS8 C 05-08-1660 Yes
LTC4252-1IMS#PBF MS-10 MS I 05-08-1661 Yes
LTC4252-1IMS#TRPBF MS-10 MS I 05-08-1661 Yes
LTC4252-1IMS8#PBF MS-8 MS8 I 05-08-1660 Yes
LTC4252-1IMS8#TRPBF MS-8 MS8 I 05-08-1660 Yes
LTC4252-2CMS#PBF MS-10 MS C 05-08-1661 Yes
LTC4252-2CMS#TRPBF MS-10 MS C 05-08-1661 Yes
LTC4252-2CMS8#PBF MS-8 MS8 C 05-08-1660 Yes
LTC4252-2CMS8#TRPBF MS-8 MS8 C 05-08-1660 Yes
LTC4252-2IMS#PBF MS-10 MS I 05-08-1661 Yes
LTC4252-2IMS#TRPBF MS-10 MS I 05-08-1661 Yes
LTC4252-2IMS8#PBF MS-8 MS8 I 05-08-1660 Yes
LTC4252-2IMS8#TRPBF MS-8 MS8 I 05-08-1660 Yes
LTC4252A-1CMS#PBF MS-10 MS C 05-08-1661 Yes
LTC4252A-1CMS#TRPBF MS-10 MS C 05-08-1661 Yes
LTC4252A-1IMS#PBF MS-10 MS I 05-08-1661 Yes
LTC4252A-1IMS#TRPBF MS-10 MS I 05-08-1661 Yes
LTC4252A-2CMS#PBF MS-10 MS C 05-08-1661 Yes
LTC4252A-2CMS#TRPBF MS-10 MS C 05-08-1661 Yes
LTC4252A-2IMS#PBF MS-10 MS I 05-08-1661 Yes
LTC4252A-2IMS#TRPBF MS-10 MS I 05-08-1661 Yes

LTC4252-1 Package Drawing
LTC4252-1 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
LTC4252-1CMS#PBF MS-10 C $3.00 $2.35 Yes
LTC4252-1CMS#TRPBF MS-10 C $2.41 Yes
LTC4252-1CMS8#PBF MS-8 C $2.55 $2.00 Yes
LTC4252-1CMS8#TRPBF MS-8 C $2.06 Yes
LTC4252-1IMS#PBF MS-10 I $3.40 $2.65 Yes
LTC4252-1IMS#TRPBF MS-10 I $2.71 Yes
LTC4252-1IMS8#PBF MS-8 I $2.90 $2.30 Yes
LTC4252-1IMS8#TRPBF MS-8 I $2.36 Yes
LTC4252-2CMS#PBF MS-10 C $3.00 $2.35 Yes
LTC4252-2CMS#TRPBF MS-10 C $2.41 Yes
LTC4252-2CMS8#PBF MS-8 C $2.55 $2.00 Yes
LTC4252-2CMS8#TRPBF MS-8 C $2.06 Yes
LTC4252-2IMS#PBF MS-10 I $3.40 $2.65 Yes
LTC4252-2IMS#TRPBF MS-10 I $2.71 Yes
LTC4252-2IMS8#PBF MS-8 I $2.90 $2.30 Yes
LTC4252-2IMS8#TRPBF MS-8 I $2.36 Yes
LTC4252A-1CMS#PBF MS-10 C $3.45 $2.50 Yes
LTC4252A-1CMS#TRPBF MS-10 C $2.56 Yes
LTC4252A-1IMS#PBF MS-10 I $3.90 $2.90 Yes
LTC4252A-1IMS#TRPBF MS-10 I $2.96 Yes
LTC4252A-2CMS#PBF MS-10 C $3.45 $2.50 Yes
LTC4252A-2CMS#TRPBF MS-10 C $2.56 Yes
LTC4252A-2IMS#PBF MS-10 I $3.90 $2.90 Yes
LTC4252A-2IMS#TRPBF MS-10 I $2.96 Yes
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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 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.

Click here to view our complete list of demo boards


  • Hot Board Insertion
  • Electronic Circuit Breaker
  • –48V Distributed Power Systems
  • Negative Power Supply Control
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