Eight-channel buck DC/DC is configurable for multi-rail systems

For general-purpose power management, Linear Technology has developed the LTC3374A, can be configured to provide two to eight independent regulated outputs with 15 possible output current configurations.

IT can be used for multi-channel applications, including industrial, automotive and communications systems. Peak efficiency is 94 per cent, one output has ± one per cent voltage accuracy and up to seven additional outputs with ± two per cent accuracy.  A power-good function indicates that the output is in regulation with ± one per cent accuracy and provides overvoltage indication.  A temperature monitor with ± three degree C accuracy is also included.

There are eight independent 1A channels with flexible sequencing and fault monitoring. Each channel is an efficient synchronous step-down regulator with its own independent 2.25 to 5.5V input supply and an output voltage range of 0.8V to VIN.  Up to four adjacent buck regulators can be combined in parallel to provide up to 4A of output current with a single shared inductor by connecting their VIN pins together, the SW pins together, and by connecting the slave bucks’ FB pin(s) to the input supply, to allow 15 output configurations.

The switching regulators operate in one of two 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. All of the switching regulators are internally compensated and need only external feedback resistors to set the output voltage. The bucks have input current limiting, soft-start to limit inrush current during start-up, and short-circuit protection. The device has a programmable and synchronisable 1.0 to 3.0MHz oscillator with a 2.0MHz default switching frequency. The quiescent current, with all DC/DCs off, is zero.  Other features include a die temperature monitor output (readable via an analogue voltage on the ‘temp’ pin) which indicates internal die temperature, and an over-temperature function, which disables the bucks at high die temperatures.

The LTC3374A is available in a thermally enhanced, low profile (0.75mm), 38-pin TSSOP and 5.0 x 7.0mm QFN packages. E-and I- grades are specified over an operating junction temperature range of –40 to 125 degree C, and the H-grade features operation from –40 to 150 degree C.



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