ML4875

July 2000 ML4875* Low Voltage Boost Regulator with Shutdown GENERAL DESCRIPTION The ML4875 is a boost regulator designed for DC to DC conversion in 1 to 3 cell battery powered systems. The combination of BiCMOS process technology, internal synchronous rectification, variable frequency operation, and low supply current make the ML4875 ideal for 1 cell applications. The ML4875 is capable of start-up with input voltages as low as 1V and is available in 5V, 3.3V, and 3V output versions with an output voltage accuracy of ±3%. Unlike regulators using external Schottky diodes, the ML4875 isolates the load from the battery when the SHDN pin is high. This is accomplished by an integrated synchronous rectifier which 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 ML4875 requires only one inductor and two capacitors to build a very small regulator circuit capable of achieving conversion efficiencies in excess of 90%. The circuit contains a RESET output which goes low when the DETECT input drops below 200mV. FEATURES s s s s s s s Guaranteed start-up and operation at 1V input Pulse Frequency Modulation and Internal Synchronous Rectification for high efficiency Isolates the load from the input during shutdown Minimum external components Low ON resistance internal switching ...