GENERAL DESCRIPTION
The SS6639 is a high efficiency step-up DC/DC controller for applications using 1 to 4 battery cells. Only three external components are required to deliver a fixed output voltage of 2.7, 3.0V, 3.3V, or 5V. The SS6639 starts up from less than 0.9V input with a 1mA load. The Pulse Frequency Modulation scheme offers optimized performance for applications with light output loading and low input voltages. The output ripple and noise are lower than with circuits operating in PSM mode.

FEATURES
 • Guaranteed start-up from less than 0.9 V.
 • High efficiency.
 • Low quiescent current.
 • Fewer external components needed.
 • Low ripple and low noise.
 • Fixed output voltage: 2.7, 3.0V, 3.3V, and 5V.
 • Driver for external transistor.
 • Space-saving package: SOT-89 and TO-92.

APPLICATIONS
 • Pagers.
 • Cameras.
 • Wireless Microphones.
 • Pocket Organizers.
 • Battery Backup Suppliers.
 • Portable Instruments.