Features and Benefits

  • 0V to 36V Wide Operating Range (60V Tolerant)
  • Drives Large External N-Channel MOSFETs for High Output Current Applications
  • Accurately Limits Inrush Current
  • Connects Highest Priority Valid Supply to Output Load
  • Changes Channel Priority in Real Time
  • ±2% OV, UV Input Comparators
  • Individually Adjustable Current Limit Time-Out for Each Channel
  • Adjustable Input Validation Time
  • Fast Switchover Minimizes VOUT Droop
  • 36-Lead 5mm × 6mm QFN and SSOP Packages

Product Details

The LTC4421 connects one of two input supplies to a common output based on user-defined priority and validity. By definition, the supply connected to V1 is the higher priority supply, although this can be changed dynamically. External resistive dividers set the undervoltage and overvoltage thresholds that bound the valid voltage window.

Strong gate drivers switch the large external N-channel MOSFETs quickly. Fast switchover circuitry minimizes output droop when changing channels while preventing reverse and cross conduction. A fast comparator detects input short circuits and quickly turns off the N-channel MOSFETs to minimize disruption.

External sense resistors set the maximum inrush and current limit currents. During current limiting, the LTC4421 controls the N-channel MOSFET gate to regulate 25mV across the sense resistor. When the sense resistor voltage has been regulated to 25mV for a user-settable time, the channel is disconnected and a fault is set.


  • High Reliability Systems
  • Server Based Back-Up Systems
  • Industrial Handheld Instruments
  • Battery Back-Up Systems

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.

Evaluation Kits (1)

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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.