LT3840 - Wide Input Range Synchronous Regulator Controller with Accurate Current Limit

Features

  • Wide Input Range: 2.5V to 60V
  • Integrated Buck-Boost Supply for 7.5V MOSFET Gate Drive
  • Programmable Constant-Current Operation with Current Monitor Output
  • Low IQ: 75μA, 12VIN to 3.3VOUT
  • Selectable Low Output Ripple Burst Mode® Operation
  • VOUT Up to 60V
  • Adjustable and Synchronizable: 50kHz to 1MHz
  • Internal OVLO Protects for Input Transients Up to 80V
  • Accurate Input Overvoltage and Undervoltage Threshold
  • Programmable Soft-Start with Voltage Tracking
  • Power Good and Output OVP
  • 28-Lead TSSOP and 38-Lead 4mm × 6mm QFN Packages
Designed for Automotive and Transportation Applications
AEC-Q100 generic family data available for specific packages


Typical Application

LT3840 Typical Application
LT3840 Typical Application

Description

The LT®3840 is a high voltage synchronous step-down switching regulator controller capable of operating from a 2.5V to 60V supply.

The LT3840’s low quiescent current, when configured for user selectable Burst Mode operation, helps extend run time in battery-powered systems by increasing efficiency at light loads. The LT3840 uses a constant frequency, current mode architecture. High current applications are possible with large N-channel gate drivers capable of driving multiple low RDS(ON) MOSFETs.

An integrated buck-boost switching regulator generates a 7.5V bias supply voltage for MOSFET gate drive and IC power allowing higher efficiency operation over the entire input voltage range and eliminating the need for an external bias voltage. An accurate current limit set point regulates the maximum output current. A current monitor reports the average output current.

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
LT3840EFE#PBF TSSOP-28 FE E 05-08-1663 (EA) Yes
LT3840EFE#TRPBF TSSOP-28 FE E 05-08-1663 (EA) Yes
LT3840EUFE#PBF 4x6 QFN-38 UFE E 05-08-1750 Yes
LT3840EUFE#TRPBF 4x6 QFN-38 UFE E 05-08-1750 Yes
LT3840HFE#PBF TSSOP-28 FE H 05-08-1663 (EA) Yes
LT3840HFE#TRPBF TSSOP-28 FE H 05-08-1663 (EA) Yes
LT3840IFE#PBF TSSOP-28 FE I 05-08-1663 (EA) Yes
LT3840IFE#TRPBF TSSOP-28 FE I 05-08-1663 (EA) Yes
LT3840IUFE#PBF 4x6 QFN-38 UFE I 05-08-1750 Yes
LT3840IUFE#TRPBF 4x6 QFN-38 UFE I 05-08-1750 Yes
LT3840MPFE#PBF TSSOP-28 FE MP 05-08-1663 (EA) Yes
LT3840MPFE#TRPBF TSSOP-28 FE MP 05-08-1663 (EA) Yes


LT3840 Package Drawing
LT3840 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
LT3840EFE#PBF TSSOP-28 E $5.43 $3.80 Yes
LT3840EFE#TRPBF TSSOP-28 E $3.86 Yes
LT3840EUFE#PBF 4x6 QFN-38 E $5.22 $3.65 Yes
LT3840EUFE#TRPBF 4x6 QFN-38 E $3.71 Yes
LT3840HFE#PBF TSSOP-28 H $6.13 $4.29 Yes
LT3840HFE#TRPBF TSSOP-28 H $4.35 Yes
LT3840IFE#PBF TSSOP-28 I $5.80 $4.06 Yes
LT3840IFE#TRPBF TSSOP-28 I $4.12 Yes
LT3840IUFE#PBF 4x6 QFN-38 I $5.46 $3.82 Yes
LT3840IUFE#TRPBF 4x6 QFN-38 I $3.88 Yes
LT3840MPFE#PBF TSSOP-28 MP $14.79 $10.35 Yes
LT3840MPFE#TRPBF TSSOP-28 MP $10.41 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
DC1909A LT3840EFE Demo Board | 4.5V ≤ VIN ≤ 60V, 80V Transients, Vout = 3.3V @ 20A $150.00
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
LT3840HFE#PBF TSSOP-28 H $6.13 $4.29 Yes
LT3840HFE#TRPBF TSSOP-28 H $4.35 Yes
LT3840IFE#PBF TSSOP-28 I $5.80 $4.06 Yes
LT3840IFE#TRPBF TSSOP-28 I $4.12 Yes
LT3840MPFE#PBF TSSOP-28 MP $14.79 $10.35 Yes
LT3840MPFE#TRPBF TSSOP-28 MP $10.41 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 Supplies
  • Industrial Systems
  • Distributed DC Power Systems

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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:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, 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

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

Models for the following parts are available in LTspice:
LT3840

Technical Support