The HT1604 series is a set of PFM step-up DC/DC converter with high efficiency and low ripple. The series features extremely low start-up voltage and high output voltage accuracy. They require only three external components to provide a programmable output voltage in 0.1V steps between 2.5~5.0V.CMOS technology ensures ultra low supply current and makes them ideal for battery-operated applications powered from one or more cells. 

The HT1604 series consists of an oscillator, a PFM control circuit, a driver transistor, a reference voltage unit, and a high  speed  comparator. They employ pulse frequency modulation (PFM) for minimum supply current and ripple at light output loading. 

The HT1604 series is available in space-saving TO92,SOT89,SOT23 and SOT23-5 packages. For SOT23-5 package, it also build-in a chip enable function to reduce power consumption during shutdown mode.