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150V Synchronous Buck-Boost Controller Eliminates Surge Protection Devices & Delivers Up to 99% Efficiency

Analog Devices » LTC3779

Analog Devices, which recently acquired Linear Technology Corporation, announces the LTC3779, a high efficiency (up to 99%) 4-switch single inductor synchronous buck-boost DC/DC controller that operates from input voltages above, below or equal to the regulated output voltage. Its 4.5 V to 150 V input voltage range is designed to operate from a high input voltage source or from an input that has high voltage surges, eliminating the need for external surge suppression devices, ideal for transportation, industrial and military applications.

Analog Devices - LTC3779

The output voltage can be set from 1.2 V to 150 V at output currents up to 10s of amps, depending on the choice of external components. The LTC3779’s powerful 1.3 Ω N-channel MOSFET gate drivers can be adjusted from 6 V to 10 V, enabling the use of logic-level or standard threshold MOSFETs. To prevent high on-chip power dissipation in high input voltage applications, the LTC3779 includes an NDRV pin which drives the gate of an optional external N-channel MOSFET acting as a low dropout linear regulator to supply IC bias power. The EXTVCC pin permits the LTC3779 to be powered from the output or other available source up to 36 V, reducing power dissipation and improving efficiency.

Efficiency and Power Loss vs Input Voltage
Efficiency and Power Loss vs Input Voltage.

Output power up to 500 W can be delivered with a single device. Higher power can be achieved when multiple circuits are configured in parallel. The operating frequency is selectable between 50 kHz and 600 kHz, and can be synchronized to an external clock over the same range. The LTC3779 employs a proprietary current mode control architecture for constant-frequency operation in buck or boost mode. The user can select either forced continuous mode or discontinuous mode to maximize light load efficiency.

Additional features include input or output average current limit, a power good output voltage monitor, adjustable soft-start and input overvoltage lockout and output voltage disconnect during shutdown. The LTC3779 is available in a 38-lead TSSOP package with additional pin spacing for high voltage operation. Two operating junction temperature grades are available, with extended and industrial versions from –40 °C to 125 °C and a high temperature automotive version from –40 °C to 150 °C. Pricing starts at $5.95 each in 1,000-piece quantities.

Summary of Features: LTC3779

  • 4-Switch Single Inductor Synchronous Buck-Boost Architecture
  • Operation with Input Voltages Above, Below or Equal to the Output Voltage
  • 4.5 V to 150 V Input Voltage Range
  • 1.2 V to 150 V Output Voltage Range
  • Up to 99% Efficiency
  • Onboard LDO or External NMOS LDO for DRVCC
  • 36 V EXTVCC LDO Powers Drivers
  • Input or Output Average Current Limit
  • Adjustable 6 V to 10 V MOSFET Gate Drivers
  • Compatible with Logic-Level or Standard Threshold NMOS
  • 500 Watts Output Power Capable with a Single Device
  • Fixed Synchronizable Operating Frequency from 50 kHz to 600 kHz
  • Output Voltage Disconnect in Shutdown
  • Adjustable Soft-Start
  • ±1% Reference Voltage Accuracy over –40 °C to 150 °C
  • TSSOP-38 Package with Additional Pin Spacing

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