LTC4281 - Hot Swap Controller with I2C Compatible Monitoring


  • Order Custom Programmed Parts
  • Allows Safe Board Insertion Into Live Backplane
  • 12-/16-Bit ADC with ±0.7% Total Unadjusted Error
  • Monitors Current, Voltage, Power and Energy
  • Internal EEPROM for Nonvolatile Configuration
  • Wide Operating Voltage Range: 2.9V to 33V
  • I2C/SMBus Digital Interface (Coexists with PMBus Devices)
  • 12V Gate Drive for Lower MOSFET RDS(ON)
  • Programmable Current Limit with 2% Accuracy
  • MOSFET Power Limiting with Current Foldback
  • Continuously Monitors MOSFET Health
  • Stores Minimum and Maximum Measurements
  • Alerts When Alarm Thresholds Exceeded
  • Reboots on I2C Command
  • Input Overvoltage/Undervoltage Protection
  • Three General Purpose Input/Outputs
  • Internal ±5% or External Timebases
  • 28-Pin 4mm × 5mm QFN Package

Typical Application

LTC4281 Typical Application
LTC4281 Typical Application


The LTC®4281 Hot Swap controller allows a board to be safely inserted and removed from a live backplane. Using an external N-channel pass transistor, board supply voltage and inrush current are ramped up at an adjustable rate. An I2C interface and onboard ADC allows for monitoring of board current, voltage, power, energy and fault status.

The device features analog foldback current limiting to limit the MOSFET power to a constant value. A wide input voltage operating range comfortably allows applications from 2.9V to 33V.

The LTC4281 is well suited to high power applications because the precise monitoring capability and accurate current limiting reduce the extremes in which both loads and power supplies must safely operate. Non-volatile configuration allows for flexibility in the autonomous generation of alerts and response to faults.


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
LTC4281CUFD#PBF 4x5 QFN-28 UFD C 05-08-1712 Yes
LTC4281CUFD#TRPBF 4x5 QFN-28 UFD C 05-08-1712 Yes
LTC4281IUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LTC4281IUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 Yes

LTC4281 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
LTC4281CUFD#PBF 4x5 QFN-28 C $7.61 $5.33 Yes
LTC4281CUFD#TRPBF 4x5 QFN-28 C $7.67 $5.39 Yes
LTC4281IUFD#PBF 4x5 QFN-28 I $8.38 $5.86 Yes
LTC4281IUFD#TRPBF 4x5 QFN-28 I $8.44 $5.92 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
DC2278A-A LTC4281 Demo Board | 12V, 50A Hot Swap Controller with Telemetry [requires DC1613] $100.00
DC2278A-B LTC4281 Demo Board with Programming Socket | 12V, 50A Hot Swap Controller with Telemetry [requires DC1613] $150.00
DC2578A Total Power Management: Hot Swap, Intermediate Bus Voltage, Point-of-Load (featuring LTC4281, LTC3886, LTC3887, LTC2975) [requires DC1613] $200.00
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Companion Boards

Part Number Description Price Documentation
DC1613A USB-to-PMBus Controller for Use with LTpowerPlay $50.00
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Click here to view our complete list of demo boards


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