LT4256-1 and LT4256-2 - Positive High Voltage Hot Swap Controllers


  • Allows Safe Board Insertion and Removal from a Live Backplane
  • Controls Supply Voltage from 10.8V to 80V
  • Foldback Current Limiting
  • Overcurrent Fault Detection
  • Drives an External N-Channel MOSFET
  • Programmable Supply Voltage Power-Up Rate
  • Undervoltage Protection
  • Latch Off Operation Mode (LT4256-1)
  • Automatic Retry (LT4256-2)
  • Available in an 8-Pin SO Package

Typical Application

LT4256-1 Typical Application


The LT4256-1/LT4256-2 are high voltage Hot Swap™ controllers that allow a board to be safely inserted and removed from a live backplane. An internal driver drives an external N-channel MOSFET switch to control supply voltages ranging from 10.8V to 80V.

The LT4256-1/LT4256-2 features an adjustable analog foldback current limit. If the supply remains in current limit for more than a programmable time, the N-channel MOSFET shuts off and the PWRGD output asserts low. The LT4256-2 automatically restarts after a time-out delay. The LT4256-1 latches off until the UV pin is cycled low.

The PWRGD output indicates when the output voltage rises above a programmed level. An external resistor string from VCC provides programmable undervoltage protection.

The LT4256 can be used as an upgrade to LT1641 designs. See Table 1 on page 14 for upgraded specifications.

The LT4256-1 and LT4256-2 are available in an 8-pin SO package that is pin compatible with the LT1641.

  Retry / Latch Off
Features Package
LT4256-1 Latch Off UV  SO-8
LT4256-2 Retry UV  SO-8
LT4256-3 Latch Off or Retry UV/OV, Open Circuit Detect SSOP-16


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
LT4256-1CS8#PBF SO-8 S8 C 05-08-1610 (S8) Yes
LT4256-1CS8#TRPBF SO-8 S8 C 05-08-1610 (S8) Yes
LT4256-1IS8#PBF SO-8 S8 I 05-08-1610 (S8) Yes
LT4256-1IS8#TRPBF SO-8 S8 I 05-08-1610 (S8) Yes
LT4256-2CS8#PBF SO-8 S8 C 05-08-1610 (S8) Yes
LT4256-2CS8#TRPBF SO-8 S8 C 05-08-1610 (S8) Yes
LT4256-2IS8#PBF SO-8 S8 I 05-08-1610 (S8) Yes
LT4256-2IS8#TRPBF SO-8 S8 I 05-08-1610 (S8) Yes

LT4256-1 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
LT4256-1CS8#PBF SO-8 C $2.50 $1.75 Yes
LT4256-1CS8#TRPBF SO-8 C $1.81 Yes
LT4256-1IS8#PBF SO-8 I $2.86 $2.00 Yes
LT4256-1IS8#TRPBF SO-8 I $2.06 Yes
LT4256-2CS8#PBF SO-8 C $2.50 $1.75 Yes
LT4256-2CS8#TRPBF SO-8 C $1.81 Yes
LT4256-2IS8#PBF SO-8 I $2.86 $2.00 Yes
LT4256-2IS8#TRPBF SO-8 I $2.06 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.

Part Number Description Price Documentation
DC1354A-A LT4256-1 Positive High Voltage Hot Swap Controllers with Latch-off (-1) $50.00
DC1354A-B LT4256-2 Positive High Voltage Hot Swap Controllers with Auto-Retry(-2) $50.00
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Click here to view our complete list of demo boards


  • Hot Board Insertion
  • Electronic Circuit Breaker/Power Bussing
  • Industrial High Side Switch/Circuit Breaker
  • 24V/48V Industrial/Alarm Systems
  • Ideally Suited for 12V, 24V and 48V Distributed Power Systems
  • 48V Telecom Systems

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