VA7910

VA7910/VA7920 REV 1.1/Feb 2006 HIGH EFFICIENCY DC-DC STEP UP CONVERT FEATURES „ 0.9V start up voltage; „ 0.9V minimum operating voltage; „ Above 95% efficiency; „ Low battery voltage detector; „ Fixed 3.3V and 5V output or adjustable output from 2V to 5V; „ Internal synchronous rectifier; „ Zero shut down current; „ Little external elements „ Ultra small TSSOP8, MSOP8 package; APPLICATION „ One to three-cell battery powered devices; „ PDA and handheld instruments; „ Cell phones; „ Pagers; „ GPS； „ Digital cameras; INTRODUCTION VA7910/VA7920 series circuits are high efficiency DC-DC step up converts, with a few external components to realize the conversion from the battery voltage to the expect output voltage. It can be widely used in PDA 、 cell phones、hand-held devices and so on. The start up voltage is guaranteed at above 0.9V input and the device keeps working. With an internal synchronous P-MOS rectifier, it doesn’t require external diode to rectify. VA7910FF is completely compatible with L6920 of ST Corporation. And VA7910DF is completely compatible with MAX1674/MAX1675 of MAXIM Corporaton. FUNCTIONAL DIAGRAM FB VREF Zero crossing comparator - Multi-way selector + -+ Voltage com parator - Logic controller + Reference Voltage comparator LBI + Current limit circuit LBO SHDN Fig1 Function Diagram OUT LX GND www.vimicro.com © 2003 Vimicro Corporation -1- DSC-VA7910/VA7920 -1 ORDERING INFORMATION Type VA7910FF VA7910DF Package TSSOP8 MSOP8 VA7910/VA7...