Power Electronics
80V Synchronous Buck-Boost Controller

80V Synchronous Buck-Boost Controller

Linear Technology Corporation announces the H- and MP-grade versions of the LT8705. This high efficiency (up to 98%) synchronous buck-boost DC/DC controller operates from input voltages above, below or equal to the regulated output voltage. The LT8705 operates over a 2.8V to 80V input voltage range and produces a fixed 1.3V to 80V output, using a single inductor with 4-switch synchronous rectification. Output power up to 250W can be delivered with a single device. Higher power can be achieved when multiple circuits are paralleled. These H- and MP-grade versions are guaranteed over operating junction temperatures from -40°C to 150°C and -55°C to 150°C, respectively.

The LT8705 has four feedback loops to regulate the input current/voltage, along with the output current/voltage. The input current and voltage feedback loops can prevent overloading of solar cells. The output current loop provides a regulated output current for a battery charger or current source. The operating frequency is selectable between 100kHz and 400kHz, and can be synchronized to an external clock. The LT8705 employs a proprietary current-mode control architecture for constant frequency operation in buck or boost mode and has powerful onboard quad N-channel MOSFET gate drivers. The user can select among forced continuous, discontinuous and Burst Mode® operation to maximize light load efficiency.

Additional features include servo pins to indicate which feedback loops are active, a 3.3V/12mA LDO, adjustable soft-start, onboard die temperature monitor and ±1.30% reference voltage accuracy over an operating junction temperature range of -55°C to 150°C. The LT8705 is available in a 38-pin 5mm x 7mm QFN, and also a 38-lead TSSOP package with additional pin spacing for high voltage operation. Pricing starts at $6.83 each in 1,000-piece quantities.

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