LT3959 - Wide Input Voltage Range Boost/SEPIC/Inverting Converter with 6A, 40V Switch


  • Wide VIN Range: 1.6V (2.5V Start-Up) to 40V
  • Positive or Negative Output Voltage Programming with a Single Feedback Pin
  • PGOOD Output Voltage Status Report
  • Internal 6A/40V Power Switch
  • Programmable Soft-Start
  • Programmable Operating Frequency (100kHz to 1MHz) with One External Resistor
  • Synchronizable to an External Clock
  • Low Shutdown Current < 1μA
  • INTVCC Regulator Supplied from VIN or DRIVE
  • Programmable Input Undervoltage Lockout with Hysteresis
  • Thermally Enhanced QFN (5mm × 6mm) and TSSOP Packages

Typical Application

LT3959 Typical Application
LT3959 Typical Application


The LT®3959 is a wide input range, current mode, DC/DC controller which is capable of regulating either positive or negative output voltages from a single feedback pin. It can be configured as a boost, SEPIC or inverting converter.

It features an internal low side N-channel MOSFET rated for 6A at 40V and driven from an internal regulated supply provided from VIN or DRIVE. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages. The operating frequency of LT3959 can be set over a 100kHz to 1MHz range with an external resistor, or can be synchronized to an external clock using the SYNC pin.

The LT3959 features soft-start and frequency foldback functions to limit inductor current during start-up and output short-circuit. A window comparator on the FBX pin reports via the PGOOD pin, providing output voltage status indication.


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
LT3959EFE#PBF TSSOP-38 FE E 05-08-1779 Yes
LT3959EFE#TRPBF TSSOP-38 FE E 05-08-1779 Yes
LT3959EUHE#PBF 5x6 QFN-36 UHE E 05-08-1836 Yes
LT3959EUHE#TRPBF 5x6 QFN-36 UHE E 05-08-1836 Yes
LT3959IFE#PBF TSSOP-38 FE I 05-08-1779 Yes
LT3959IFE#TRPBF TSSOP-38 FE I 05-08-1779 Yes
LT3959IUHE#PBF 5x6 QFN-36 UHE I 05-08-1836 Yes
LT3959IUHE#TRPBF 5x6 QFN-36 UHE I 05-08-1836 Yes

LT3959 Package Drawing
LT3959 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
LT3959EFE#PBF TSSOP-38 E $4.63 $3.24 Yes
LT3959EFE#TRPBF TSSOP-38 E $3.30 Yes
LT3959EUHE#PBF 5x6 QFN-36 E $4.36 $3.05 Yes
LT3959EUHE#TRPBF 5x6 QFN-36 E $3.11 Yes
LT3959IFE#PBF TSSOP-38 I $5.27 $3.69 Yes
LT3959IFE#TRPBF TSSOP-38 I $3.75 Yes
LT3959IUHE#PBF 5x6 QFN-36 I $5.03 $3.52 Yes
LT3959IUHE#TRPBF 5x6 QFN-36 I $3.58 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
DC1853A LT3959EUHE Boost Demo Board | 2V-10Vin; Vout = 12V @ 2A $175.00
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  • Automotive
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Design Tools


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