LT8391 - 60V Synchronous 4-Switch Buck-Boost LED Controller with Spread Spectrum

Features

  • 4-Switch Single Inductor Architecture Allows VIN Above, Below or Equal to VOUT
  • Synchronous Switching: Up to 98% Efficiency
  • Proprietary Peak-Buck Peak-Boost Current Mode
  • Wide VIN Range: 4V to 60V
  • Wide VOUT Range: 0V to 60V (51V LED)
  • ±3% LED Current Accuracy
  • 2000:1 External and 128:1 Internal PWM Dimming
  • High Side PMOS PWM Switch Driver
  • Integrated Bootstrap Diodes
  • No Top MOSFET Refresh Noise in Buck or Boost
  • Adjustable and Synchronizable: 150kHz to 650kHz
  • Flicker-Free Spread Spectrum for Low EMI
  • Open and Short LED Protection with Fault Reporting
  • Available in 28-Lead TSSOP with Exposed Pad and 28-Lead QFN (4mm × 5mm)

Typical Application

LT8391 Typical Application
LT8391 Typical Application

Description

The LT®8391 is a synchronous 4-switch buck-boost LED controller that regulates LED current from input voltage above, below, or equal to the output voltage. The proprietary peak-buck peak-boost current mode control scheme allows adjustable and synchronizable 150kHz to 650kHz fixed frequency operation, or internal ±15% triangle spread spectrum operation for low EMI. With 4V to 60V input, 0V to 60V output, and seamless low noise transitions between operation regions, the LT8391 is ideal for LED driver and battery charger applications in automotive, industrial, and battery-powered systems.

The LT8391 provides both internal (up to 128:1) and external (up to 2000:1) LED current PWM dimming with a high-side PMOS switch. Two CTRL pins provide flexible 20:1 analog dimming with ±3% LED current accuracy at 100mV full scale. Fault protection is provided to detect an open or short LED condition, during which the LT8391 retries, latches off, or keeps running.

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
LT8391EFE#PBF TSSOP-28 FE E 05-08-1663 (EB) Yes
LT8391EFE#TRPBF TSSOP-28 FE E 05-08-1663 (EB) Yes
LT8391EUFD#PBF 4x5 QFN-28 UFD E 05-08-1712 Yes
LT8391EUFD#TRPBF 4x5 QFN-28 UFD E 05-08-1712 Yes
LT8391IFE#PBF TSSOP-28 FE I 05-08-1663 (EB) Yes
LT8391IFE#TRPBF TSSOP-28 FE I 05-08-1663 (EB) Yes
LT8391IUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LT8391IUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 Yes


LT8391 Package Drawing
LT8391 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
LT8391EFE#PBF TSSOP-28 E $6.64 $4.65 Yes
LT8391EFE#TRPBF TSSOP-28 E $6.70 $4.71 Yes
LT8391EUFD#PBF 4x5 QFN-28 E $6.64 $4.65 Yes
LT8391EUFD#TRPBF 4x5 QFN-28 E $6.70 $4.71 Yes
LT8391IFE#PBF TSSOP-28 I $7.31 $5.12 Yes
LT8391IFE#TRPBF TSSOP-28 I $7.37 $5.18 Yes
LT8391IUFD#PBF 4x5 QFN-28 I $7.31 $5.12 Yes
LT8391IUFD#TRPBF 4x5 QFN-28 I $7.37 $5.18 Yes
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* 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
DC2345A LT8391EFE Demo Board | Sync Buck-Boost LED Driver, 4V ≤ VIN ≤ 60V, VLED = 25V @ 2A $309.00
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Click here to view our complete list of demo boards

Applications

  • Automotive Head Lamps/Running Lamps
  • High Power LED Lighting

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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:
LT8391

Technical Support