1. Products
  2. Power Management
  3. Switching Regulators
  4. Step-Down (Buck) Regulators
  5. External Power Switch Buck Controllers
  6. LTC1439


Features and Benefits

  • Maintains Constant Frequency at Low Output Currents
  • Dual N-Channel MOSFET Synchronous Drive
  • Programmable Fixed Frequency (PLL Lockable)
  • Wide VIN Range: 3.5V to 36V Operation
  • Ultrahigh Efficiency
  • Very Low Dropout Operation: 99% Duty Cycle
  • Low Dropout, 0.5A Linear Regulator for VPP
  • Generation or Low Noise Audio Supply
  • Built-In Power-On Reset Timer
  • Programmable Soft Start
  • Low-Battery Detector
  • Remote Output Voltage Sense
  • Foldback Current Limiting (Optional)
  • Pin Selectable Output Voltage
  • Logic-Controlled Micropower Shutdown: IQ < 30µA
  • Output Voltages from 1.19V to 9V
  • Available in 28- and 36-Lead SSOP Packages

Product Details

The LTC1438/LTC1439 are dual, synchronous stepdown switching regulator controllers which drive external N-channel power MOSFETs in a phase-lockable fixed frequency architecture. The Adaptive Power output stage selectively drives two N-channel MOSFETs at frequencies up to 400kHz while reducing switching losses to maintain high efficiencies at low output currents.

An auxiliary 0.5A linear regulator using an external PNP pass device provides a low noise, low dropout voltage source. A secondary winding feedback control pin (SFB1) guarantees regulation regardless of load on the main output by forcing continuous operation.

An additional comparator is available for use as a low battery detector. A power-on reset timer (POR) is included which generates a signal delayed by 65536/fCLK (typ 300ms) after the output is within 5% of the regulated output voltage. Internal resistive dividers provide pin selectable output voltages with remote sense capability on one of the two outputs.

The operating current levels are user-programmable via external current sense resistors. Wide input supply range allows operation from 3.5V to 30V (36V maximum).


  • Notebook and Palmtop Computers, PDAs
  • Portable Instruments
  • Battery-Operated Devices
  • DC Power Distribution Systems

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 (2)

Tools & Simulations


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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
LTC1439CG#PBF Material Declaration Reliability Data 36-Lead SSOP
LTC1439CG#TRPBF Material Declaration Reliability Data 36-Lead SSOP
LTC1439CGW#PBF Material Declaration Reliability Data 36-Lead SSOP (Wide 0.3 Inch)
LTC1439CGW#TRPBF Material Declaration Reliability Data 36-Lead SSOP (Wide 0.3 Inch)
LTC1439EG#PBF Material Declaration Reliability Data 36-Lead SSOP
LTC1439EG#TRPBF Material Declaration Reliability Data 36-Lead SSOP
LTC1439IG#PBF Material Declaration Reliability Data 36-Lead SSOP
LTC1439IG#TRPBF Material Declaration Reliability Data 36-Lead SSOP
LTC1439IGW#PBF Material Declaration Reliability Data 36-Lead SSOP (Wide 0.3 Inch)
LTC1439IGW#TRPBF Material Declaration Reliability Data 36-Lead SSOP (Wide 0.3 Inch)
Wafer Fabrication Data R393 Reliability Data

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Buy Now Pricing

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List Pricing

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Lead Times

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