Features and Benefits

  • Expands Up to 4 Phases per Chip
  • Up to 80V Input or Output Voltage
  • Cascade with Multiple Chips for High Current Applications
  • Supports Up to 18 Distinct Phases from 20° to 180°
  • Phases Can Share Phase Angle
  • Excellent DC and Transient Current Sharing
  • Phase-Lockable Fixed Frequency 125kHz to 1MHz
  • Supports Bidirectional Current Flow
  • RSENSE or DCR Current Sensing
  • Eliminates the Need to Route Sensitive Feedback and Control Signals.
  • 52-Lead (7mm × 8mm) QFN Package

Product Details

The LT8551 is a multiphase expander for synchronous boost DC/DC converters. It operates in tandem with any synchronous boost DC/DC converter to increase the load current capability by adding additional phases, which are clocked out-of-phase to reduce ripple current and filtering capacitance. It easily adds phases without the need to route sensitive feedback and control signals.

The LT8551 integrates 5V gate drivers and can support up to four boost phases per device. Multiple LT8551 devices can be used for up to 18 phases. It accurately monitors and adjusts the current of each channel to achieve excellent DC and transient current sharing. 

The LT8551 operates over a fixed frequency from 100kHz to 1MHz or can be synchronized to an external clock.


  • High Current Distributed Power Systems
  • Telecom, Datacom, and Storage Systems
  • Industrial and Automotive

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

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.


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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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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