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  4. Step-Down (Buck) Regulators
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  6. LT1938

Data Sheet
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Overview

Features and Benefits

  • Wide Input Voltage Range: 3.6V to 25V
  • 2.2A Maximum Output Current
  • Adjustable Switching Frequency: 300kHz to 2.8MHz
  • Low Shutdown Current: IQ < 1µA
  • Integrated Boost Diode
  • Power Good Flag
  • Saturating Switch Design: 0.18Ω On-Resistance
  • 1.265V Feedback Reference Voltage
  • Output Voltage: 1.265V to 20V
  • Soft-Start Capability
  • Small 10-Pin Thermally Enhanced (3mm × 3mm) DFN Package

Product Details

The LT1938 is an adjustable frequency (300kHz to 2.8MHz) monolithic buck switching regulator that accepts input voltages up to 25V. A high efficiency 0.18Ω switch is included on the die along with a boost Schottky diode and the necessary oscillator, control and logic circuitry. Current mode topology is used for fast transient response and good loop stability. The LT1938's high operating frequency allows the use of small, low cost inductors and ceramic capacitors resulting in low output ripple while keeping total solution size to a minimum. The low current shutdown mode reduces input supply current to less than 1µA while a resistor and capacitor on the RUN/SS pin provide a controlled output voltage ramp (soft-start). A power good flag signals when VOUT reaches 90% of the programmed output voltage. The LT1938 is available in a 3mm × 3mm DFN package with Exposed Pad for low thermal resistance.

Applications

  • Automotive Battery Regulation
  • Power for Portable Products
  • Distributed Supply Regulation
  • Industrial Supplies
  • Wall Transformer Regulation

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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)

Documentation & Resources

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  • Data Sheets (1)
  • Reliability Data (1)
  • User Guides (1)
    • Document Type

    Tools & Simulations

    LTspice

    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.

    To launch ready-to-run LTspice demonstration circuits for this part:

    Step 1: Download and install LTspice on your computer.

    Step 2: Click on the link in the section below to download a demonstration circuit.

    Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.

    LTspice

    LTspice Simulations

    LT1938 Demo Circuit - 2.2A, 25V. 2.8MHz Step_down Regulator (24V to 3.3V @ 2.2A)

    Models for the following parts are available in LTspice:

    LT1938

    Product Recommendations

    LT1938 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.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
    LT1938EDD#PBF Material Declaration Reliability Data 10-Lead DFN (3mm x 3mm w/ EP)
    LT1938EDD#TRPBF Material Declaration Reliability Data 10-Lead DFN (3mm x 3mm w/ EP)
    LT1938IDD#PBF Material Declaration Reliability Data 10-Lead DFN (3mm x 3mm w/ EP)
    LT1938IDD#TRPBF Material Declaration Reliability Data 10-Lead DFN (3mm x 3mm w/ EP)
    Wafer Fabrication Data R530 Reliability Data

    Support & Discussions

    LT1938 Contact ADI Technical Support »
    LT1938 Ask your question »
    LT1938 Contact ADI Technical Support » LT1938 Ask your question »

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