Configurable buck DC/DCs deliver 8 A from 2 to 4 independent outputs

January 09, 2015 // By Graham Prophet
LTC3371 is a highly integrated general-purpose power management solution for systems requiring multiple low voltage power supplies. The device features four synchronous buck converters, each powered from independent 2.25V to 5.5V inputs, and each configurable to share up to four of eight available 1A power stages.

With eight unique output current configurations, the LTC3371 provides flexibility and ease of reuse across many different applications. The device is suitable for a wide variety of multichannel industrial, automotive, communications and distributed power systems.

The device's buck power stages can be connected in parallel by simply combining their respective VIN and SW pins and programming the desired configuration on the C1-C3 pins. Up to four adjacent power stages can be combined on a single channel, resulting in eight unique output configurations ranging from a quad 2A buck to a dual 4A buck. A single inductor may be used for each buck regulator, and any unused power stages may be added to one of the high power channels for improved overall efficiency.

The LTC3371's precision enable pin thresholds, independent power-on reset outputs, watchdog timer and die temperature monitor, provide flexible and reliable power-up sequencing and system monitoring. All of the switching regulators are internally compensated and need only external feedback resistors to set the output voltages. The common buck switching frequency can be programmed with an external resistor, synchronised to an external oscillator or set to a default internal 2 MHz clock. The switching regulators may be programmed to operate either in Burst Mode operation for high efficiency at light loads or in forced continuous PWM mode for lowest noise at light loads. The bucks are phased in 90° steps to reduce noise and input ripple, have forward and reverse current limiting, soft-start to limit inrush current during start-up, and short-circuit protection.

Thermally enhanced 38-pin packages comprise a low profile 5 x 7 mm QFN and TSSOP. 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. Pricing starts at $4.15 (1000).

Linear Technology;