1A Buck-Boost, 600mA Buck Dual Synchronous DC/DC Converter

The second channel is a synchronous buck regulator which can deliver up to 600mA of continuous output current to voltages as low as 0.80V. An uncommitted gain block can be configured as an LDO or a battery-good comparator. This combination is ideal for powering applications such as DSPs/microcontrollers that require both a 3.3V I/O rail and a 0.8V to 1.8V rail for the core voltage. The LTC3520 operates from 2.2V to 5.5V inputs while switching frequency is user programmable between 100kHz and 2MHz, enabling designers to maximize efficiency while keeping externals small. The combination of its high switching frequency and a 4mm x 4mm QFN package ensures a very compact solution footprint for handheld applications.

The LTC3520's unique synchronous buck-boost topology on its 1A channel enables it to regulate a constant output voltage when the input voltage is above, equal to or below the output, enabling complete use of the Li-Ion battery's stored energy. The LTC3520 utilizes automatic BurstMode operation to offer only 55uA (both channels) of no load quiescent current. For applications requiring very low noise, the Burst Mode® operation can be defeated and replaced with a forced continuous mode. Shutdown current is less than 1uA, further extending battery life. Each channel has independent internal soft-start, enabling design flexibility. Other features include short-circuit protection and over-temperature protection.