LTC3445 Datasheet | Linear Technology

I2C Controllable Buck Regulator with Two LDOs in a 4mm × 4mm QFN Features Buck Regulator - High Efficiency: Up to 93% - 600m A 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 LDOs - Two LDO Regulators: 0.3V Dropout at 50m A Power Path Controller - Dynamically Regulates VCC BATT I2C - Standard (100k Hz) or Fast Mode (400k Hz) - 24-Lead (4mm × 4mm) QFN Package U APPLICATIO S - Intel’s Microprocessor Supply (PXA27X) - Portable Instruments , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. Power Path is a trademark of Linear Technology Corporation. I2C is a trademark of Philips Electronics N.V. Protected by U.S. Patents, including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131, Spread Spectrum patent pending. DESCRIPTIO The LTC®3445 contains a high efficiency monolithic synchronous current mode buck regulator, two LDO regulators, a Power Path TM controller and an I2CTM interface. The buck regulator has a 6-bit programmable output range of 0.85V to 1.55V. Also, the buck regulator uses either a constant (1.5MHz) or a spread spectrum switching frequency. Using the spread spectrum option allows for a lower noise regulated output as well as low noise at the input. In addition, the regulated output voltage slew rate is programmable via the I2C interface. The LTC3445 contains two LDO voltage regulators. The regulator output voltages are externally resistor programmable. Each LDO is capable of delivering up to 50m A. The LTC3445 contains control circuitry (Power Path) for automatic back-up battery selection. VBACKUP is typically a coin cell. Typical supply current during operation is only 360µA and drops to 27µA in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3445 ideal for single Li-Ion battery-powered applications....