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DC/DC controller supports 2.8-80V input voltage range

Posted: 14 Feb 2013 ?? ?Print Version ?Bookmark and Share

Keywords:DC/DC controller? MOSFET? battery?

Linear Technology Corp. has unleashed what it says is a very high efficiency (up to 98 per cent) synchronous buck-boost DC/DC controller that operates from input voltages above, below or equal to the regulated output voltage. The LT8705 can be used in a wide range of applications such as a voltage stabiliser in telecom and automotive requirements, as well as in solar or high impedance sources and battery systems.

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 device operates from 2.8-80V input voltage range and produces a 1.3-80V output, using a single inductor with 4-switch synchronous rectification. Output power up to 250W can be delivered with a single device. Higher output power can be achieved when multiple circuits are paralleled.

The operating frequency is selectable between 100kHz and 400kHz, and can be synchronised to an external clock. The LT8705 uses 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 maximise 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 per cent reference voltage accuracy over an operating junction temperature range of -40C to 125C. The LT8705 is available in a 38-pin 5 x 7mm QFN, and also a 38-lead TSSOP package with additional pin spacing for high voltage operation. Pricing starts at $5.95 each in 1,000-piece quantities.

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