1. Products
  2. Power Management
  3. Switching Regulators
  4. Step-Up (Boost) Regulators
  5. Internal Power Switch Boost Regulators
  6. LTC3421


Features and Benefits

  • Synchronous Rectification: Up to 96% Efficiency
  • True Output Disconnect
  • Inrush Current Limiting
  • Very Low Quiescent Current: 12µA
  • Up to 1.5A Continuous Output Current
  • Fixed Frequency Operation Up to 3MHz
  • 0.5V to 4.5V Input Range
  • 2.4V to 5.25V Adjustable Output Voltage
  • Guaranteed 1V Start-Up
  • Programmable Current Limit
  • Programmable Soft-Start
  • Synchronizable Oscillator
  • Manual or Automatic Burst Mode® Operation
  • Low-Battery Comparator
  • <1µA Shutdown Current
  • 1.22V Reference Output Voltage
  • Small (4mm × 4mm) Thermally Enhanced QFN Package

Product Details

The LTC3421 is a high efficiency, current mode, fixed frequency, step-up DC/DC converter with true output disconnect and inrush current limiting. The device includes a 0.10Ω N-channel MOSFET switch and a 0.14Ω P-channel synchronous rectifier. This product has the ability to simply program the output voltage, switching frequency, current limit, soft-start, Burst Mode threshold and loop compensation with external passive components.

Quiescent current is only 12µA during Burst Mode operation, maximizing battery life in portable applications. The oscillator frequency can be programmed up to 3MHz and can be synchronized to an external clock applied to the SYNC pin. An open-drain uncommitted low-battery comparator is included. The part maintains operation in applications with a secondary cell powering the output voltage during shutdown.

Other features include: 1µA shutdown, anti-ringing control, thermal limit and reference output.

The LTC3421 is available in a small 4mm × 4mm QFN package.


  • Handheld Computers
  • Cordless Phones
  • GPS Receivers
  • Battery Backup Supplies

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.

Evaluation Kits (1)

Tools & Simulations


LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.


Models for the following parts are available in LTspice:


Product Recommendations

LTC3421 Companion Parts

Recommended Suggested Oscillator

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.View our quality and reliability program and certifications for more information.

Part Number Material Declaration Reliability Data Pin/Package Drawing CAD Symbols, Footprints & 3D Models
LTC3421EUF#PBF Material Declaration Reliability Data 24-Lead QFN (4mm x 4mm x 0.75mm w/ EP)
LTC3421EUF#TRPBF Material Declaration Reliability Data 24-Lead QFN (4mm x 4mm x 0.75mm w/ EP)
Wafer Fabrication Data R415 Reliability Data

PCN-PDN Information

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Sample & Buy

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Buy Now Pricing

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List Pricing

(*)The 1Ku 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. authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


Lead Times

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Evaluation Boards

Pricing displayed is based on 1-piece.

Up to two boards can be purchased through Analog.com. 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.