Eight-Channel Configurable 1A Buck DC/DCs for Multi-Rail Systems

Feb. 5, 2013

Linear Technology Corp. announces the LTC3375, a highly-integrated general-purpose power management solution for systems requiring multiple low voltage power supplies. The device features eight independent 1A channels with I²C control, flexible sequencing and fault monitoring in a compact QFN package. Each channel is a high efficiency synchronous step-down regulator with its own independent 2.25V to 5.5V input supply and an output voltage range of 0.425V to VIN. In addition, the LTC3375's buck DC/DCs may be connected in parallel to achieve higher output currents up to 4A per output with a single shared inductor. Up to four adjacent regulators can be combined, resulting in 15 different possible output configurations. All of the switching regulators are internally compensated and need only external feedback resistors to set the default output voltage.

The LTC3375's pushbutton ON/OFF/RESET control, power-on reset and watchdog timer provide flexible and reliable power-up sequencing and system monitoring. All buck output voltages can be adjusted via I²C for margining or power optimization. The LTC3375 features a programmable and synchronizable 1MHz to 3MHz oscillator with a 2MHz default switching frequency. The device also contains a high voltage input shunt regulator controller, and quiescent current is only 11µA with all DC/DCs off. It is ideal for a wide variety of multichannel applications including industrial, automotive and communications systems.

Adjacent buck regulators can be combined in a master/slave configuration by connecting their VIN and SW pins together, and connecting the slave bucks' FB pin(s) to the input supply. The switching regulators offer two operating modes: Burst Mode® operation (power-up default mode) for higher efficiency at light loads, and forced continuous PWM mode for lower noise at light loads. The I²C interface can be used to select mode of operation, phasing, feedback regulation voltage and switch slew rate. The bucks have forward and reverse current limiting, soft-start to limit inrush current during start-up, short-circuit protection and slew rate control for lower radiated EMI. Other features include a die temperature monitor output (readable via I²C or the analog voltage on the TEMP pin), which indicates internal die temperature and an overtemperature (OT) warning function, indicating high die temperature.

The LTC3375 is available from stock in a thermally enhanced, low profile (0.75mm) 48-pin 7mm x 7mm exposed pad QFN package. E and I grades are specified over an operating junction temperature range of -40°C to +125°C, and the H grade features operation from -40°C to +150°C. 1000-piece pricing starts at $5.45 each for the E grade.


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