Synchronous buck regulator is Intel xScale Power Manager in QFN package

Intel xScale Microprocessor Power Manager in a Tiny 4mm x 4mm QFN

Milpitas, CA — December 8, 2004 — Linear Technology Corporation announces the LTC3445, a compact, high efficiency xScale microprocessor power supply in a 4mm x 4mm QFN package. It contains a high efficiency monolithic synchronous current mode buck regulator, two LDO regulators, a PowerPath controller and an I2 C interface in a single QFN package. Its 2.5V to 5.5V input voltage range makes the LTC3445 ideal for single Li-Ion battery-powered applications.

The synchronous buck regulator can deliver up to 600mA of output current with efficiencies of up to 93%. The user can select either a constant (1.5MHz) or a spread spectrum switching frequency. The spread spectrum option allows for a lower noise regulated output as well as low noise at the input. For processor core voltages, the onboard I2C interface controls a 6-bit programmable dynamically adjustable output voltage range of 0.85V to 1.55V and a slew rate control. The LTC3445 also contains two LDO voltage regulators to power additional xScale voltages such as VSRAM and VPLL. Both LDO output voltages are programmable with external resistors and can deliver up to 50mA of output current.

The LTC3445 contains control circuitry (PowerPath) for automatic battery back-up (typically a coin cell battery) when the main battery is disabled. Automatic Burst Mode operation reduces light load supply current to only 360uA and drops to 27uA in shutdown for extended battery life.

The LTC3445 packaged in a 4mm x 4mm QFN-24, is available from stock. Pricing starts at $2.45 each for 1,000-piece quantities.

Summary of LTC3445 Features
* Buck Regulator
— High Efficiency: Up to 93%
— 600mA Output Current (VCC1 = 3V, VOUT = 1.3V)
— Programmable Output Voltage: 0.85V to 1.55V
— 2.5V to 5.5V Input Voltage Range
— 1.5MHz Constant Frequency or Spread Spectrum Option
— Soft-Start
— Two LDO Regulators: 0.3V Dropout at 50mA
* PowerPath Controller
— Dynamically Regulates VCC BATT
* I2 C
— Standard (100kHz) or Fast Mode (400kHz)
— 24-Lead (4mm X 4mm) QFN Package

Linear Technology Corporation, 1630 McCarthy Boulevard, Milpitas, CA 95035-7417. Tel: 1-800-4-LINEAR (800-454-6327), or go to the company's web site:

LTC3445 data sheet

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