Power & Analogue

Holtek HT77xx

PFM Asynchronous Step-up DC to DC Converter (100mA) The HT77xx 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 fixed output voltage of 1.8V, 2.2V, 2.7V, 3.0V, 3.3V, 3.7V or 5.0V. CMOS technology ensures ultra low supply current and makes them ideal for battery-operated applications powered from one or more cells. The HT77xx 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. These devices are available in space saving 3-pin SOT89, 3-pin SOT23 and 5-pin SOT23 packages. For 5-pin SOT23 package, it also build-in a chip enable function to reduce power consumption during shutdown mode. Applications · Palmtops/PDAs · Portable communicators/Smartphones · Cameras/Camcorders · Battery-powered equipment

Features

· Low start-up voltage: 0.7V (Typ.), 0.9V (Max.) · High efficiency: 85% (Typ.), VOUT³2.7V · High output voltage accuracy: ±2.5% · Output voltage: 1.8V, 2.2V, 2.7V, 3.0V, 3.3V, 3.7V, 5.0V · Output current up to 100mA · Ultra low supply current IDD2: 4mA (Typ.) · Low ripple and low noise · Low shutdown current: 0.5mA (Typ.) · 3-pin SOT89, 3-pin SOT23 and 5-pin SOT23 package