I2C Controlled 4-Output Synchronous Step-Down DC/DC Converter

29th February 2008

ES Admin

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Linear Technology has announced the LTC3562, a quad channel, high efficiency, 2.25 MHz, synchronous buck converter that can deliver dual 600mA and dual 400mA continuous outputs from a 3mm x 3mm QFN package. Using a constant frequency current mode architecture, the LTC3562 operates from an input voltage range of 2.7V to 5.5V, making it ideal for single cell Li-Ion/polymer, or multicell alkaline/NiCad/NiMH applications.

The LTC3562 has two channels (600mA and 400mA) that allow the output voltage to be adjusted by programming the feedback voltages between 425mV and 800mV in 25mV increments. The other two channels (600mA and 400mA) feature fixed outputs that can be programmed between 600mV and 3.775V in 25mV steps programming is done an I2C interface. This level of independent output voltage control makes the LTC3562 ideal for managing multiple supply rails. Its 2.25MHz switching frequency enables the utilization of tiny, low cost ceramic capacitors and inductors less than a 1mm in height. This, combined with a 3mm x 3mm QFN package, provides a very compact quad output solution for handheld and other dense board applications.

The LTC3562 delivers up to 96% efficiency and its LDO mode operation minimizes quiescent current to only 100uA in no load conditions while minimizing noise. The LTC3562 can also be programmed to use Burst Mode®, pulse skipping or continuous mode operation in lieu of the LDO mode. The LTC3562 also utilizes low dropout 100% duty cycle operation to allow output voltages up to VIN, further extending battery run-time. Each channel has internal soft-start and independent enable and mode control, enhancing design flexibility. Other features include short-circuit protection and over-temperature protection.