LTC3251 - 500mA High Efficiency, Low Noise, Inductorless Step-Down DC/DC Converters


  • Up to 500mA Output Current
  • No Inductors
  • 2.7V to 5.5V Input Voltage Range
  • 2x Efficiency Improvement Over LDOs
  • 2-Phase, Spread Spectrum Operation for Low Input and Output Noise
  • Shutdown Disconnects Load from VIN
  • Adjustable Output Voltage Range: 0.9V to 1.6V
    Fixed Output Voltages: 1.2V, 1.5V
  • Super Burst, Burst and Burst Defeat Operating Modes
  • Low Operating Current: IIN = 35µA (Burst Mode® Operation)
  • Super Burst Operating Current: IIN = 10µA
  • Low Shutdown Current: IIN = 0.01µA Typ
  • Soft-Start Limits Inrush Current at Turn-On
  • Short-Circuit and Overtemperature Protected
  • Available in a Thermally Enhanced 10-Pin MSOP Package

Typical Application

LTC3251 Typical Application
LTC3251 Typical Application


The LTC3251/LTC3251-1.2/LTC3251-1.5 are 2-phase charge pump step-down DC/DC converters that produce a regulated output from a 2.7V to 5.5V input. The parts use switched capacitor fractional conversion to achieve twice the typical efficiency of a linear regulator. No inductors are required. VOUT is resistor programmable from 0.9V to 1.6V or fixed at 1.2V or 1.5V, with up to 500mA of load current available.

A unique 2-phase spread spectrum architecture provides a very low noise regulated output as well as low noise at the input.* The parts have four operating modes: Continuous Spread Spectrum, Spread Spectrum with Burst Mode operation, Super Burst™ mode operation and shutdown.

Low operating current (35µA in Burst Mode operation, 10µA in Super Burst mode operation) and low external parts count make the LTC3251/LTC3251-1.2/LTC3251-1.5 ideally suited for space-constrained battery-powered applications. The parts are short-circuit and over-temperature protected, and are available in a thermally enhanced 10-pin MSOP package.


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
LTC3251EMSE-1.2#PBF MS-10E MSE E 05-08-1664 Yes
LTC3251EMSE-1.2#TRPBF MS-10E MSE E 05-08-1664 Yes
LTC3251EMSE-1.5#PBF MS-10E MSE E 05-08-1664 Yes
LTC3251EMSE-1.5#TRPBF MS-10E MSE E 05-08-1664 Yes
LTC3251EMSE#PBF MS-10E MSE E 05-08-1664 Yes
LTC3251EMSE#TRPBF MS-10E MSE E 05-08-1664 Yes

LTC3251 Package Drawing
LTC3251 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
LTC3251EMSE-1.2#PBF MS-10E E $2.79 $1.95 Yes
LTC3251EMSE-1.2#TRPBF MS-10E E $2.01 Yes
LTC3251EMSE-1.5#PBF MS-10E E $2.79 $1.95 Yes
LTC3251EMSE-1.5#TRPBF MS-10E E $2.01 Yes
LTC3251EMSE#PBF MS-10E E $2.79 $1.95 Yes
LTC3251EMSE#TRPBF MS-10E E $2.01 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
DC506A LTC3251EMSE Demo Board | Spread-Spectrum, Low Noise, Inductorless Step-Down Charge Pump, 3.2V ≤ VIN ≤ 5.5V, Vout @ Up to 500mA $75.00
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Click here to view our complete list of demo boards


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