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  4. Step-Down (Buck) Regulators
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  6. LT8640

Data Sheet Rev. E
PDF
CN | JP
User Guide
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Alternative Parts

LT8614
LT8614

42V, 4A Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current

LT8640S
LT8640S

42V, 6A Synchronous Step-Down Silent Switcher 2 with 2.5μA Quiescent Current

LT8641
LT8641

65V, 3.5A Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current

New Content (1)

Webcast
Simulating Power Solution Designs using LTspice

Overview

Features and Benefits

  • Silent Switcher® Architecture
    • Ultralow EMI Emissions
    • Spread Spectrum Frequency Modulation
  • High Efficiency at High Frequency
    • Up to 96% Efficiency at 1MHz, 12VIN to 5VOUT
    • Up to 95% Efficiency at 2MHz, 12VIN to 5VOUT
  • Wide Input Voltage Range: 3.4V to 42V
  • 5A Maximum Continuous Output, 7A Peak Transient Output
  • Ultralow Quiescent Current Burst Mode® Operation
    • 2.5µA IQ Regulating 12VIN to 3.3VOUT
    • Output Ripple < 10mVP-P
  • Fast Minimum Switch On-Time: 30ns
  • Low Dropout Under All Conditions: 100mV at 1A
  • Forced Continuous Mode (LT8640-1 Only)
  • Safely Tolerates Inductor Saturation in Overload
  • Adjustable and Synchronizable: 200kHz to 3MHz
  • Peak Current Mode Operation
  • Output Soft-Start and Tracking
  • Small 18-Lead 3mm × 4mm QFN and Side Wettable QFN
  • AEC-Q100 Qualified for Automotive Applications

Product Details

The LT8640/LT8640-1 step-down regulator features Silent Switcher architecture designed to minimize EMI emissions while delivering high efficiency at frequencies up to 3MHz. An ultralow 2.5µA quiescent current—with the output in full regulation—enables applications requiring highest efficiency at very small load currents.

The LT8640/LT8640-1 allows high VIN to low VOUT conversion at high frequency with a fast minimum top switch on-time of 30ns. The SYNC/MODE pin selects between Burst Mode operation, spread spectrum mode, synchronization to an external clock, and either pulse-skipping (LT8640) or forced continuous mode (LT8640-1).

Package SYNC/MODE ≠ 0 VC COMP H-GRADE CLKOUT INTERNAL CAPS
LT8640 QFN Pulse-Skipping Internal Yes No No
LT8640-1 QFN FCM Internal Yes No No
LT8640S LQFN FCM Internal No Yes Yes
LT8643S LQFN FCM External No Yes Yes
LT8640S-2 LQFN FCM Internal Yes Yes No
LT8643S-2 LQFN FCM External Yes Yes No

APPLICATIONS

  • Automotive and Industrial Supplies
  • General Purpose Step-Down
  • GSM Power Supplies

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Product Lifecycle icon-recommended Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Evaluation Kits (1)

Documentation & Resources

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  • Data Sheet (1)
  • Reliability Data (1)
  • User Guide (1)
  • Webcast (6)
  • Book & eBook (1)
  • Solutions Bulletin & Brochure (2)
  • Video (1)
  • Technical Article (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

    LT8640 Demo Circuit - 5V 2MHz µPower Ultralow EMI Step-Down Converter (5.7-42V to 5V @ 5A)

    Models for the following parts are available in LTspice:

    LT8640
    LT8640-1
    LT8640A
    LT8640S-2

    LTpowerCAD

    LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.

    To open the project file for this circuit:

    Step 1: Download and install LTpowerCAD on your computer.

    Step 2: Click on the link(s) in the section below to download part-specific project files.

    Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.

    LTPowerCAD

    LTpowerCAD Project Files

    LT8640 Project - 42V, 5A Monolithic μPower Buck Silent Switcher (5.7-42V to 5V @ 5A)
    LT8640 Project - 42V, 5A Monolithic μPower Buck Silent Switcher (8-42V to 5V @ 5A)

    Design tools for the following parts are available in LTpowerCAD:

    LT8640
    LT8640S

    Product Recommendations

    LT8640 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
    LT8640EUDC#PBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640EUDC#TRPBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640EUDC-1#PBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640EUDC-1#TRPBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640EUDCF#PBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640EUDCF#TRPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640EUDCF-1#PBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640EUDCF-1#TRPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640HUDC#PBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640HUDC#TRPBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640HUDC-1#PBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640HUDC-1#TRPBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640HUDCF#PBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640HUDCF#TRPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640IUDC#PBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640IUDC#TRPBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640IUDC-1#PBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640IUDC-1#TRPBF Material Declaration Reliability Data 20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)
    LT8640IUDCF#PBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640IUDCF#TRPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640IUDCF-1#PBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640IUDCF-1#TRPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640JUDCF#PBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640JUDCF#TRPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640JUDCF#WPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640JUDCF#WTRPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640JUDCF-1#PBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640JUDCF-1#TRPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640JUDCF-1#WPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    LT8640JUDCF-1#WTRPBF Material Declaration Reliability Data 20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)
    Wafer Fabrication Data R570 Reliability Data

    PCN-PDN Information

    Select a model from the dropdown below to subscribe to PCN/PDN notifications and view past notifications as well.

    Select Model for PCN Information
    • LT8640EUDC#PBF Production
    • LT8640EUDC#TRPBF Production
    • LT8640EUDCF#PBF Production
    • LT8640EUDCF#TRPBF Production
    • LT8640HUDC#PBF Production
    • LT8640HUDC#TRPBF Production
    • LT8640HUDCF#PBF Production
    • LT8640HUDCF#TRPBF Production
    • LT8640IUDC#PBF Production
    • LT8640IUDC#TRPBF Production
    • LT8640IUDCF#PBF Production
    • LT8640IUDCF#TRPBF Production
    • LT8640JUDCF#PBF Production
    • LT8640JUDCF#TRPBF Production

    Support & Discussions

    LT8640 Discussions

    RE: LT8640S/43S compensation pin
    All LT8640 Discussions
    LT8640 Contact ADI Technical Support »
    LT8640 Ask your question »
    LT8640 Contact ADI Technical Support » LT8640 Ask your question »

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