Power Electronics

I2C-Controllable Buck Regulator Comes In Tiny DFN

Linear Technology’s LTC3447 is a 600-mA, high-efficiency, current-mode buck regulator in a 3-mm x 3-mm DFN-10 package. Using an onboard I2C interface, the output voltage can be set between 0.69 V and 2.05 V using an internal 6-bit DAC. The LTC3447's 2.5-V to 5.5-V input voltage range makes it suitable for powering Intel's xScale microprocessor core voltage in single Li-ion or multicell alkaline, NiCd, or NiMH battery-powered applications.

The LTC3447 synchronous buck regulator can deliver up to 600 mA of output current with efficiencies of up to 93%. The I2C interface frequency can be set at either the standard 100 kHz or the 400 kHz "fast mode" while output voltages can be programmed with 21.6-mV resolution. A constant 1.0-MHz switching frequency ensures low noise and allows the use of tiny surface-mount inductors and capacitors.

For extended battery life, automatic burst mode operation reduces light load supply current to only 33 µA, dropping to 1µA in shutdown. For low-noise applications, the burst mode feature can be disabled. Other features include soft-start and start up power good blanking. Pricing starts at $1.95 each for 1000-piece quantities.

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