Linear Technology Introduces High Efficiency Synchronous Buck-Boost DC/DC Controller

Photocoupler

Linear Technology Corporation has launched the LTC3789, a highly efficient synchronous buck-boost DC/DC controller with up to 98% efficiency. This device is capable of delivering a stable output voltage regardless of whether the input voltage is higher, lower, or equal to the output. Traditional high-power boost and buck circuits often require a transformer or two separate DC/DC converters. However, the LTC3789 operates in a single inductor and 4-switch synchronous rectification mode, enabling it to deliver up to 150W of output power in a single package. By connecting multiple modules in parallel, even greater power outputs can be achieved.

The LTC3789 supports an optional fixed frequency range from 200kHz to 600kHz, and it can also synchronize with an external clock within the same range using its integrated phase-locked loop (PLL). With a wide input voltage range of 4V to 38V and an output range of 0.8V to 38V, this versatile controller is ideal for applications such as industrial control, automotive systems, solar energy, and high-power battery-powered devices.

In both buck and boost modes, the LTC3789 uses a proprietary current-mode control architecture to ensure constant frequency operation. It features four powerful N-channel MOSFET gate drivers, along with an accurate constant current regulation loop that works across a broad input voltage range. The device includes input current limit functionality to prevent overloading the power supply, and an output current limit to ensure stable performance in applications like battery chargers or LED drivers. Additionally, it offers comprehensive fault protection against overvoltage, overcurrent, and short-circuit conditions in all operating modes.

During shutdown, the LTC3789 disconnects both the input and output voltages. Users can choose between continuous mode or pulse-skip mode to optimize efficiency under light load conditions. The device also features an adjustable soft-start function, a power-good output signal, and ±1.5% reference accuracy over a wide temperature range of -40°C to 125°C.

The LTC3789 is available in two compact packages: a 28-pin 4mm x 5mm QFN and a 28-lead SSOP. The price for 1,000 units is $4.65 per piece. For more details, visit the official website.

Performance Summary: LTC3789

• Single inductor architecture
• Operates with input voltage higher than, lower than, or equal to the output voltage
• Input voltage range: 4V to 38V
• Output voltage range: 0.8V to 38V
• Programmable input or output current limit
• Synchronous rectification
• Up to 98% efficiency
• Integrated MOSFET gate driver
• Supports up to 150W output power
• Output disconnection during shutdown
• PLL-based fixed frequency from 200kHz to 600kHz
• Power-good output signal
• ±1.5% reference voltage accuracy over -40°C to +125°C
• Current mode control for fast transient response and easy loop compensation
• Overvoltage and overcurrent protection
• 5.5V internal and external VCC LDO