DC/DC Controller Is Ideal For Portable Instruments

Linear Technology has introduced the LTC3868/-1, a low quiescent current, two-phase dual output synchronous step-down DC/DC controller. The LTC3868/-1 draws only 170uA with one output active and only 300uA when both outputs are active. This is said to make the controller ideal for battery-powered applications. With both outputs shut down, the LTC3868/-1 draws only 8uA. The LTC3868/-1 has an input supply range of 4-24V and each output can be set from 0.8V to 14V at output currents up to 20A.

With efficiency as high as 95 per cent, a LTC3868/-1 DC/DC converter is well suited for powering industrial and medical devices, along with portable instruments, notebook and netbook computers. The LTC3868/-1 operates with a user-adjustable, fixed frequency between 50kHz and 900kHz, and can be synchronised to an external clock from 75kHz to 850kHz using its phase-locked loop. The user can select from continuous operation, pulse skipping and low ripple burst-mode operation during light loads.

These parts also safely start up with a pre-biased load by powering up and down in pulse skip mode. The LTC386/-1's two-phase operation reduces input capacitance requirements and its current mode architecture provides easy loop compensation and fast transient response. Both outputs have adjustable soft-start to control the turn-on time, and the output overload protection feature latches off the converter until the input voltage is recycled.

The LTC3868/-1 also features a tight +/- 1.5 per cent reference voltage accuracy over a -40C to 85C operating temperature range. The LTC3868 is the fully featured part with additional functions beyond the LTC3868-1 including a clock out, phase modulation, two power-good outputs and adjustable current limit. The LTC3868 is offered in a 32-lead 5 x 5mm QFN package and the LTC3868-1 in 28-pin SSOP or 4 x 5mm QFN-28 packages.

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