ML4771

July 2000 ML4771* High Current Boost Regulator GENERAL DESCRIPTION The ML4771 is a continuous conduction boost regulator designed for DC to DC conversion in multiple cell battery powered systems. Continuous conduction allows the regulator to maximize output current for a given inductor. The maximum switching frequency can exceed 200kHz, allowing the use of small, low cost inductors. The ML4771 is capable of start-up with input voltages as low as 1.8V, and the output voltage can be set anywhere between 3.0V and 5.5V by an external resistor divider connected to the SENSE pin. An integrated synchronous rectifier eliminates the need for an external Schottky diode and provides a lower forward voltage drop, resulting in higher conversion efficiency. In addition, low quiescent battery current and variable frequency operation result in high efficiency even at light loads. The ML4771 requires a minimum number of external components to build a very small regulator circuit capable of achieving conversion efficiencies exceeding 85%. FEATURES s Guaranteed full load start-up and operation at 1.8V input Continuous conduction mode for high output current Very low supply current (20µA output referenced) for micropower operation Pulse Frequency Modulation and Internal Synchronous Rectification for high efficiency Maximum switching frequency > 200kHz Minimum external components Low ON resistance internal switching FETs Adjustable output voltage (3.0V to 5.5V) s s s s s s s (* Indicates P...