Converter Provides Flyback Voltage Conversion

Designed to develop a regulated 3.3V at 700 mA from a single lithium-ion cell, UCC3954 converter boasts of high efficiency, constant frequency conversion over the full 4.2V to 2.4V lithium-ion voltage range. The device's topology references the lithium ion cell's positive terminal to system ground and provides flyback voltage conversion with a single inductor. It is well-suited for applications such as cellular phones PDAs, and portable instruments. The device operates as a fixed 200-kHz switching frequency voltage mode flyback converter and incorporates both low battery indication and shutdown functions. A low-battery LED driver provides visual warning when the battery is nearly exhausted. Other features include a trimmed -1.1V reference and internal feedback scaling resistors, a precision error amplifier, low quiescent current drain in shutdown mode, and soft-start functionality.