LT3976 - 40V, 5A, 2MHz Step-Down Switching Regulator with 3.3μA Quiescent Current

Features

  • Ultralow Quiescent Current:
    3.3μA IQ at 12VIN to 3.3VOUT
  • Low Ripple Burst Mode® Operation
    Output Ripple < 15mVP-P
  • Wide Input Range: Operation from 4.3V to 40V
  • 5A Maximum Output Current
  • Excellent Start-Up and Dropout Performance
  • Adjustable Switching Frequency: 200kHz to 2MHz
  • Synchronizable Between 250kHz to 2MHz
  • Accurate Programmable Undervoltage Lockout
  • Low Shutdown Current: IQ = 700nA
  • Power Good Flag
  • Soft-Start Capability
  • Thermal Shutdown Protection
  • Current Limit Foldback with Soft-Start Override
  • Saturating Switch Design: 75mΩ On-Resistance
  • Small, Thermally Enhanced 16-Lead MSOP and 24-Lead 3mm × 5mm QFN Packages
Designed for Automotive and Transportation Applications
AEC-Q100 generic family data available for specific packages


Typical Application

LT3976 Typical Application
LT3976 Typical Application

Description

The LT®3976 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 40V. Low quiescent current design consumes only 3.3μA of supply current while regulating with no load. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 15mV in a typical application. The LT3976 can supply up to 5A of load current and has current limit foldback to limit power dissipation during short-circuit. A low dropout voltage of 500mV is maintained when the input voltage drops below the programmed output voltage, such as during automotive cold crank.

An internally compensated current mode topology is used for fast transient response and good loop stability. A high efficiency 75mΩ switch is included on the die along with a boost Schottky diode. An accurate 1.02V threshold enable pin can be driven directly from a microcontroller or used as a programmable undervoltage lockout. A capacitor on the SS pin provides a controlled inrush current (soft-start). A power good flag signals when VOUT reaches 91.6% of the programmed output voltage. The LT3976 is available in small 16-lead MSOP and 24-lead 3mm × 5mm QFN packages with exposed pad for low thermal resistance.

Packaging

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
Drawing
RoHS
LT3976EMSE#PBF MS-16E MSE E 05-08-1667 Yes
LT3976EMSE#TRPBF MS-16E MSE E 05-08-1667 Yes
LT3976EUDD#PBF 3x5 QFN-24 UDD E 05-08-1833 Yes
LT3976EUDD#TRPBF 3x5 QFN-24 UDD E 05-08-1833 Yes
LT3976HMSE#PBF MS-16E MSE H 05-08-1667 Yes
LT3976HMSE#TRPBF MS-16E MSE H 05-08-1667 Yes
LT3976IMSE#PBF MS-16E MSE I 05-08-1667 Yes
LT3976IMSE#TRPBF MS-16E MSE I 05-08-1667 Yes
LT3976IUDD#PBF 3x5 QFN-24 UDD I 05-08-1833 Yes
LT3976IUDD#TRPBF 3x5 QFN-24 UDD I 05-08-1833 Yes


LT3976 Package Drawing
LT3976 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
(1-99)
Price
(1k)*
RoHS
LT3976EMSE#PBF MS-16E E $5.36 $3.75 Yes
LT3976EMSE#TRPBF MS-16E E $3.81 Yes
LT3976EUDD#PBF 3x5 QFN-24 E $5.36 $3.75 Yes
LT3976EUDD#TRPBF 3x5 QFN-24 E $3.81 Yes
LT3976HMSE#PBF MS-16E H $6.26 $4.38 Yes
LT3976HMSE#TRPBF MS-16E H $4.44 Yes
LT3976IMSE#PBF MS-16E I $5.90 $4.13 Yes
LT3976IMSE#TRPBF MS-16E I $4.19 Yes
LT3976IUDD#PBF 3x5 QFN-24 I $5.90 $4.13 Yes
LT3976IUDD#TRPBF 3x5 QFN-24 I $4.19 Yes
Buy NowRequest Samples
* 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
DC1848A LT3976 Demo Board I Buck with 3.3µA Iq, 4.3V ≤ VIN ≤ 40V, Vout = 3.3V @ 5A $175.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

Please contact your local sales representative for more information regarding reliability reports and AEC-Q100 data or to inquire about parts that are not included. For more information, view our Automotive and Transportation page

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT3976HMSE#PBF MS-16E H $6.26 $4.38 Yes
LT3976HMSE#TRPBF MS-16E H $4.44 Yes
LT3976IMSE#PBF MS-16E I $5.90 $4.13 Yes
LT3976IMSE#TRPBF MS-16E I $4.19 Yes
LT3976IUDD#PBF 3x5 QFN-24 I $5.90 $4.13 Yes
LT3976IUDD#TRPBF 3x5 QFN-24 I $4.19 Yes
Buy NowRequest Samples
* 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.

Applications

  • Automotive Battery Regulation
  • Portable Products
  • Industrial Supplies

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LT3976

LTpowerCAD

The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD

Design tools for the following parts are available in LTpowerCAD:
LT3976

Technical Support