LTC3789 - High Efficiency, Synchronous, 4-Switch Buck-Boost Controller


  • Single Inductor Architecture Allows VIN Above, Below or Equal to the Regulated VOUT
  • Programmable Input or Output Current
  • Wide VIN Range: 4V to 38V
  • 1% Output Voltage Accuracy: 0.8V < VOUT < 38V
  • Synchronous Rectification: Up to 98% Efficiency
  • Current Mode Control
  • Phase-Lockable Fixed Frequency: 200kHz to 600kHz
  • No Reverse Current During Start-Up
  • Power Good Output Voltage Monitor
  • Internal 5.5V LDO
  • Quad N-Channel MOSFET Synchronous Drive
  • VOUT Disconnected from VIN During Shutdown
  • True Soft-Start and VOUT Short Protection, Even in Boost Mode
  • Available in 28-Lead QFN (4mm × 5mm) and 28-Lead SSOP Packages

Typical Application

LTC3789 Typical Application
LTC3789 Typical Application


The LTC®3789 is a high performance buck-boost switching regulator controller that operates from input voltages above, below or equal to the output voltage. The constant-frequency, current mode architecture allows a phase-lockable frequency of up to 600kHz, while an output current feedback loop provides support for battery charging. With a wide 4V to 38V (40V maximum) input and output range and seamless, low noise transitions between operating regions, the LTC3789 is ideal for automotive, telecom and battery-powered systems.

The operating mode of the controller is determined through the MODE/PLLIN pin. The MODE/PLLIN pin can select between pulse-skipping mode and forced continuous mode operation and allows the IC to be synchronized to an external clock. Pulse-skipping mode offers high efficiency and low ripple at light loads, while forced continuous mode operates at a constant frequency for noise-sensitive applications.

A PGOOD pin indicates when the output is within 10% of its designed set point. The LTC3789 is available in low profile 28-pin 4mm × 5mm QFN and narrow SSOP packages.


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
LTC3789EGN#PBF SSOP-28 GN E 05-08-1641 (GN28) Yes
LTC3789EGN#TRPBF SSOP-28 GN E 05-08-1641 (GN28) Yes
LTC3789EUFD#PBF 4x5 QFN-28 UFD E 05-08-1712 Yes
LTC3789EUFD#TRPBF 4x5 QFN-28 UFD E 05-08-1712 Yes
LTC3789IGN#PBF SSOP-28 GN I 05-08-1641 (GN28) Yes
LTC3789IGN#TRPBF SSOP-28 GN I 05-08-1641 (GN28) Yes
LTC3789IUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LTC3789IUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 Yes

LTC3789 Package Drawing
LTC3789 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
LTC3789EGN#PBF SSOP-28 E $6.64 $4.65 Yes
LTC3789EGN#TRPBF SSOP-28 E $4.75 Yes
LTC3789EUFD#PBF 4x5 QFN-28 E $6.64 $4.65 Yes
LTC3789EUFD#TRPBF 4x5 QFN-28 E $4.75 Yes
LTC3789IGN#PBF SSOP-28 I $7.64 $5.35 Yes
LTC3789IGN#TRPBF SSOP-28 I $5.45 Yes
LTC3789IUFD#PBF 4x5 QFN-28 I $7.64 $5.35 Yes
LTC3789IUFD#TRPBF 4x5 QFN-28 I $5.45 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
DC1523A LTC3789EGN Demo Board | Sync Buck-Boost Controller, 5V ≤ VIN ≤ 36V, VOUT = 12V @ 5A $200.00
DC1721A LTC4000EGN/LTC3789EGN Demo Board u 14.6V, 5A Battery Charger with 6VIN to 36VIN Buck-Boost Converter $250.00
DC1757B LTC3789EGN Buck-Boost Demo Board | VIN = 6V to 36V, V OUT = 12V @ 12A $200.00
DC1878A LTC3789EGN Demo Board I Vin Range: 8V to 75V, VOUT: 12V @ 5A $200.00
DC1881A LTC3789EUFD Buck-Boost Demo Board | VIN = 6V to 36V, VOUT = 12V @ 2.5A Contact Factory
DC2253A LTC3789EGN Demo Board | Sync Buck-Boost, 6V ≤ VIN ≤ 36V; VOUT = 12V @ 25A $250.00
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Click here to view our complete list of demo boards


  • Automotive Systems
  • Distributed DC Power Systems
  • High Power Battery-Operated Devices
  • Industrial Control

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