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Features and Benefits

  • Seamless, Automatic Transition Between Two Input Power Sources
  • Wide Input Voltage Range: 2.4V to 42V
  • Wide Output Voltage Range: 0.818V to VIN
  • Up to 2.5A Continuous Output Current
  • Pin Selectable Priority and Ideal Diode-OR Modes
  • Burst Mode® Operation, IQ = 2μA
  • 95% Efficiency at 1A, VIN = 12V, VOUT = 5V
  • 1μA Current in Shutdown
  • Programmable Input UVLO Thresholds
  • Input Valid, Priority Channel and PGOOD Indicators
  • 200kHz to 2.2MHz Fixed Frequency PWM
  • Synchronizable to an External Clock
  • Current Mode Control with 60ns Minimum On-Time
  • Minimal External Components
  • Thermally Enhanced 28-Lead 4mm × 5mm QFN and 28-Lead TSSOP Packages

Product Details

The LTC3126 is a high efficiency synchronous buck converter with an internal no-loss PowerPath supporting seamless operation from two separate input power sources. Pin selectable ideal diode-OR and priority input modes with user programmable undervoltage lockout thresholds provide full control over the transition between the input power sources. The fast, automatic switchover provided by the internal PowerPath eliminates the need for hold-up capacitors and minimizes disturbances on the output rail. An active input channel indicator and independent input and output power good signals provide complete feedback of the power system status.

A wide 2.4V to 42V input voltage range, 2.5A output current capability and 2μA Burst Mode operation quiescent current facilitate use of the LTC3126 with a wide variety of power sources including supercapacitors, automotive batteries, unregulated wall adapters and single to multicell stacks of most battery chemistries. Additional features include 1μA current in shutdown, internal soft-start and thermal protection. The LTC3126 is available in thermally enhanced 28-lead 4mm × 5mm QFN and 28-lead TSSOP packages.


  • Portable Industrial/Communications Test Equipment
  • Battery and Supercapacitor Backup Power
  • Automotive Power with Battery Backup
  • Uninterruptible Power Supplies

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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Product Recommendations

LTC3126 Companion Parts

Recommended Related Parts

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.

PCN-PDN Information

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Lead Times

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Evaluation Boards

Pricing displayed is based on 1-piece.

Up to two boards can be purchased through To order more than two, please purchase through one of our listed distributors.

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.