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Power/Alternative Energy??

Programmable PMIC designed for 1-cell Li-ion polymer systems

Posted: 30 Aug 2010 ?? ?Print Version ?Bookmark and Share

Keywords:buck-boost regulator? I2C control?

A new compact digitally programmable high efficiency multioutput power supply plus dual string LED driver IC is now available for high-power single-cell lithium-ion/polymer cell systems. Linear Technology Corp.'s LTC3675 has seven independent rails featuring I2C control, flexible sequencing and fault monitoring in 28mm2 QFN package.

It has four high-efficiency synchronous step-down regulators (1A, 1A, 500mA and 500mA), a high current/high efficiency buck-boost regulator (1A), a synchronous boost regulator (1A), a dual-string 40V-LED driver and an always-on LDO. Flexible and reliable power-up sequencing are ensured by pushbutton on/off/reset control, precision enable inputs and a power-on reset output. The I2C interface provides complete regulator control, status reporting and a maskable interrupt output. With all DC/DCs off, current consumption is just 16uA.

 Linear LTC3675

The 2.25MHz buck-boost regulator, enabled via its enable pin or via I2C, can deliver up to 1A load current for a programmed output of 3.3V. The IC can control the mode of operation (burst mode or PWM), feedback regulation voltage and switch slew rate. It also features forward current limiting, soft-start to limit inrush current during start-up, short-circuit protection and slew rate control.

The boost regulator can deliver 1A load current for a programmed output voltage of up to 5V. Boost DC/DC enable, mode of operation (burst mode or PWM), feedback regulation voltage and switch slew rate can all be controlled via I2C. It has forward and reverse current limiting, soft start to limit inrush current during start-up, short-circuit protection, slew rate control for lower radiated EMI and true output disconnect when in shutdown.

The LTC3675's constant frequency, current mode 40V LED driver can regulate up to 25mA of current through each of two series 10-LED strings. LED enable, 60dB brightness control and up/down gradation are programmed using I2C. The LED driver can function as a general-purpose high-voltage boost converter with a 1.6A (typ) switch current limit. It can boost from below 3V to up to 40V output at 55mA.





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