Linear reveals switching regulator controller
Linear Technology
switching regulator controller
Linear Technology has announced the LTC3853, a triple-output synchronous step-down switching regulator controller with coincident or ratiometric tracking that safely powers pre-biased loads.
The 4.5V to 24V (28V maximum) input range encompasses a wide variety of applications, including most intermediate bus voltages.
The strong on-board gate drivers power all N-channel Mosfet stages and can produce output currents up to 20A per phase with output voltages ranging from 0.8V to 13.5V.
Applications include point-of-load regulation in datacom, telecom, set-top boxes, basestations and multifunction printers, where multiple voltage rails must deliver high power with low heat dissipation in a small system size.
A constant-frequency current mode architecture allows a selectable fixed or phase-lockable (PLL) frequency from 250kHz to 750kHz.
Power loss and supply noise are minimised by operating the three stages 120 degrees out of phase.
The LTC3853 can also be used in a 2+1 configuration, with output stages 1 and 2 180 degrees out of phase.
Opti-Loop compensation allows a wide range of output capacitance and ESR values, including all ceramic input and output capacitors.
Output current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) or by using an optional sense resistor.
Current foldback limits Mosfet heat dissipation during short-circuit and overload conditions.
In addition, the LTC3853 has adjustable soft-start to control the turn-on time.
Selectable burst mode operation, pulse skipping or continuous inductor current modes are user-controlled to optimise light load efficiency against output ripple.
It features a precision 0.8V reference with an accuracy of +/-1 per cent over a -40C to 125C operating temperature range.
With up to 98 per cent duty cycle, it has a very low drop-out voltage, a useful feature for extending run times in battery-powered applications.
The LTC3853 is offered in a thermally enhanced 6mm x 6mm QFN-40 package.
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