ML4863

Tem ommercial Extended C 70˚C to C 0˚ -2 ment dheld Equip an H e bl ta or for P G FEATURIN ge perature Ran July 2000 ML4863* High Efficiency Flyback Controller GENERAL DESCRIPTION The ML4863 is a flyback controller designed for use in multi-cell battery powered systems such as PDAs and notebook computers. The flyback topology is ideal for systems where the battery voltage can be either above or below the output voltage, and where multiple output voltages are required. The ML4863 uses the output voltage as the feedback control signal to the current mode variable frequency flyback controller. In addition, a synchronous rectifier control output is supplied to provide the highest possible conversion efficiency (greater than 85% efficiency over a 1mA to 1A load range). The ML4863 has been designed to operate with a minimum number of external components to optimize space and cost. FEATURES s Variable frequency current mode control and synchronous rectification for high efficiency Minimum external components Guaranteed start-up and operation over a wide input voltage range (3.15V to 15V) High frequency operation (>200kHz) minimizes the size of the magnetics Flyback topology allows multiple outputs in addition to the regulated 5V Built-in overvoltage and current limit protection s s s s s *Some Packages Are Obsolete BLOCK DIAGRAM SHDN 3 VIN VFB 4.5V LDO BIAS & UVLO VFB VCC VCC 5 1 4 – + VFB VREF VCC GND 8 OUT 1 A1 6 I CURRENT COMPARATOR + – COMP SWITCHING CONTROL ...