Synchronous 1A Buck-Boost and 600mA Buck Converters

The LTC3520 combines 1A buck-boost and 600mA synchronous buck DC/DC converters in a tiny 4mm x 4mm package. A programmable switching frequency allows the efficiency to be optimized while minimizing the solution footprint. Both converters feature soft-start and current limit protection. The uncommitted gain block can be configured as an LDO or utilized as a battery-good comparator.

The buck converter is current mode controlled with internal synchronous rectification to improve efficiency. Pin-selectable Burst Mode operation can be enabled to improve light load efficiency, or the buck converter can be operated in low noise PWM mode for sensitive applications.

The buck-boost converter provides continuous conduction operation to maximize efficiency and minimize noise. At light loads, use of Burst Mode operation will improve efficiency.

The LTC3520 provides a <1µA shutdown mode and over- temperature shutdown on both converters. The LTC3520 is available in a low profile (0.75mm) 24-lead 4mm x 4mm QFN package.

Applications

* Portable Media Players

* Digital Cameras

* Handheld PCs, PDAs

* GPS Receivers

* Dual High Efficiency DC/DC Converters:

* Buck-Boost (VOUT: 2.2V to 5.25V, IOUT = 1A at

VOUT = 3.3V, VIN ≥ 3V)

* Buck (VOUT: 0.8V to VIN, IOUT = 600mA)

* 2.2V to 5.5V Input Voltage Range

* Pin-Selectable Burst Mode® Operation

* Uncommitted Gain Block for LDO Controller, Battery Good Indication or Sequencing

* Programmable 100kHz to 2MHz Switching Frequency

* 55μA Total Quiescent Current for Both Converters in Burst Mode Operation

* Thermal and Overcurrent Protection

* <1μA Quiescent Current in Shutdown

* 24-Lead 4mm × 4mm QFN Package