with Steve Knoth, Senior Product Marketing Engineer, Power Products

The LTC3675 is a digitally programmable high efficiency multi-output power supply plus dual string LED driver IC optimized for high power single cell Li-Ion/Polymer applications. The DC/DCs consist of four synchronous buck converters (1A/1A/500mA/500mA), one synchronous boost DC/DC (1A), and one buck-boost DC/DC (1A) all powered from a 2.7V to 5.5V input. The 40V LED driver can regulate up to 25mA of current through two LED strings with up to 10 LEDs each. The LED driver may also be configured as a general purpose high voltage boost converter.

DC/DC enables, output voltages, switch slew rates and operating modes may all be independently programmed over I2C or used in standalone mode via simple I/O and power-up defaults. The buck DC/DCs may be used independently or paralleled to achieve higher output currents with a shared inductor. LED enable, 60dB brightness control and up/down gradation are programmed using I2C. Alarm levels for low VIN and high die temperature may also be programmed via I2C with a maskable interrupt output to monitor DC/DC and system faults.

Pushbutton ON/OFF/RESET control and a power-on reset output provide flexible and reliable power-up sequencing. The LTC3675 is available in a low profile (0.75mm), thermally enhanced 44-lead 4mm × 7mm QFN package.