High Efficiency, Synchronous, 4-Switch Buck-Boost Controller
Features and Benefits
- Single Inductor Architecture Allows VIN Above, Below or Equal to VOUT
- Wide VIN Range: 4V to 36V Operation
- Synchronous Rectification: Up to 98% Efficiency
- Current Mode Control
- ±1% Output Voltage Accuracy: 0.8V < VOUT < 30V
- Phase-Lockable Fixed Frequency: 200kHz to 400kHz
- Power Good Output Voltage Monitor
- Internal LDO for MOSFET Supply
- Quad N-Channel MOSFET Synchronous Drive
- VOUT Disconnected from VIN During Shutdown
- Adjustable Soft-Start Current Ramping
- Foldback Output Current Limiting
- Selectable Low Current Modes
- Output Overvoltage Protection
- Available in 24-Lead SSOP and Exposed Pad (5mm × 5mm) 32-Lead QFN Packages
The LTC3780 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 400kHz. With a wide 4V to 30V (36V maximum) input and output range and seamless transfers between operating modes, the LTC3780 is ideal for automotive, telecom and battery-powered systems.
The operating mode of the controller is determined through the FCB pin. For boost operation, the FCB mode pin can select among Burst Mode® operation, discontinuous mode and forced continuous mode. During buck operation, the FCB mode pin can select among skip-cycle mode, discontinuous mode and forced continuous mode. Burst Mode operation and skip-cycle mode provide high efficiency operation at light loads while forced continuous mode and discontinuous mode operate at a constant frequency.
Fault protection is provided by an output overvoltage comparator and internal foldback current limiting. A power good output pin indicates when the output is within 7.5% of its designed set point.
- Automotive Systems
- Telecom Systems
- DC Power Distribution Systems
- High Power Battery-Operated Devices
- Industrial Control
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (3)
Demonstration circuit 1155A is a compact high efficiency synchronous buck-boost DC/DC converter solution featuring the LTC3780EUH controller. with 6V to 32V input range. It can supply 2A maximum load current at 12V output. The constant frequency current mode architecture allows a phase-lockable frequency of up to 400kHz.
Demonstration circuit 686, featuring the LTC3780 controller, is a high efficiency buck-boost DC/DC converter that can regulate its output from input voltages both above and below the output. The demo board delivers 12V@5A from an input range of 5V to 32V.
Demonstration circuit 1046A is a non-isolated, high efficiency buck-boost DC/DC supply featuring LTC3780EG and LTC4440ES6. The LTC3780 is a high performance 4-switch synchronous buck boost regulator and the LTC4440 is a 100V-rated FET driver. The input voltage of the demo board is designed for 36V to 72V. The output voltage is 48V. At 25C° room temperature, the maximum output current is 5A without a cooling fan and 6A with 150LFM air flow for cooling. An optional 12V bias flyback supply using the LTC3803 is stuffed on the board to power the LTC3780 and LTC4440.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, 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.
Models for the following parts are available in LTspice:
LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.
To open the project file for this circuit:
Step 1: Download and install LTpowerCAD on your computer.
Step 2: Click on the link(s) in the section below to download part-specific project files.
Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.
LTpowerCAD Project Files
Design tools for the following parts are available in LTpowerCAD:
LTC3780 Companion Parts
Recommended µModule Regulator
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.