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Dual Output, Multiphase Step-Down DC/DC Controller Operates with Power Blocks & DrMOS Devices

18th February 2010

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Datasheet

Linear Technology introduced the LTC3860, a dual output synchronous step-down DC/DC controller with multiphase operation, differential output voltage sensing and high frequency operation. This controller works in conjunction with external power train devices such as Power Blocks and DrMOS, as well as discrete N-channel MOSFETs and associated gate drivers, enabling flexible design configurations. Up to 12 phases can be paralleled and clocked out-of-phase to minimize input and output filtering for very high current requirements (up to 300A). Applications include high current power distribution and industrial systems, DSP and ASIC supplies.

The differential amplifier provides true remote output voltage sensing of both VOUT and ground terminals, enabling high accuracy regulation where IR losses occur through vias, trace runs and interconnects. The LTC3860 operates with a VCC voltage ranging from 3V to 5.5V, a VIN voltage (drain voltage for the high-side MOSFET) from 3V to 24V and produces output voltages from 0.6V to 5V. The device's voltage mode control architecture allows for a selectable fixed operating frequency from 250kHz to 1.25MHz or it can be synchronized over the same range with its phased-lock loop (PLL). The output current is sensed by monitoring the voltage drop across the output inductor (DCR) for maximum efficiency or using a sense resistor. Its adjustable current limit can be configured for very low sense voltages (0mV to 50mV) to minimize power loss. The LTC3860's current sharing loop enables accurate current sharing between phases across multiple IC's both DC and during a load transient.

Additional features include adjustable soft start or tracking, output overvoltage protection and two power good output signals. Furthermore, it maintains ±1% reference voltage accuracy over an operating temperature range of -40°C to 125°C.