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260A step-down DC/DC controller operates from 3V to 5.5V

Posted: 11 Feb 2016 ?? ?Print Version ?Bookmark and Share

Keywords:Linear Technology? DC/DC controller? MOSFET? FPGA? ASIC?

Linear Technology Corp. has rolled out the door a quad output multiphase synchronous step-down DC/DC controller flaunting accurate current sharing between phases and differential output voltage sensing. The LTC7851/每1 works in conjunction with external power train devices such as DrMOS and power blocks as well as discrete N每channel MOSFETs and associated gate drivers, enabling flexible design configurations.

Up to eight phases with two ICs can be paralleled and can be clocked out-of-phase to minimise input and output filtering for very high current requirements up to 260A. Applications include power distribution and industrial systems, FPGA, DSP, processor and ASIC supplies.

LTC7851-1

The LTC7851/每1 has an internal current share loop that equalises current between phases when paralleled, enabling accurate current sharing between phases across multiple ICs, both in steady state and during a transient event. It operates with a VCC supply voltage from 3V to 5.5V, is designed for step-down conversion from an input voltage from 3V to 27V and produces one to four independent output voltages ranging from 0.6V to 5V. The device has a voltage mode control architecture that allows for a selectable fixed operating frequency from 250kHz to 2.25MHz or it can be synchronised to an external clock over the same range. The output current is sensed by monitoring the voltage drop across the output inductor (DCR) for maximum efficiency or by using a low value sense resistor. The onboard differential amplifiers provide true remote output voltage sensing for all outputs of both VOUT and ground terminals for high accuracy regulation.

LTC7851-1

LTC7851-1 block diagram

The LTC7851每1 is similar to the LTC7851, but with a lower current sense amplifier gain, geared for power train applications using DrMOS with internal current sense capability. Additional features for each phase include current monitoring, adjustable current limit, programmable soft-start or tracking, and a power good signal. Furthermore, it maintains ㊣0.75 per cent reference voltage accuracy over an operating temperature range of 每20∼C to 85∼C.

The LTC7851/每1 is housed in a 58每lead 5mm x 9mm QFN package and is available from stock. The 1000每piece price starts at $4.27 each.





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