600 mA Sync-Rect PFM Step-Up DC-DC Converter with True-Cutoff and Ring-Killer

NCP1421 is a monolithic micropower high−frequency step−up switching converter IC specially designed for battery−operated hand−held electronic products up to 600 mA loading. It integrates Sync−Rect to improve efficiency and to eliminate the external Schottky Diode. High switching frequency (up to 1.2 MHz) allows for a low profile, small−sized inductor and output capacitor to be used. When the device is disabled, the internal conduction path from LX or BAT to OUT is fully blocked and the OUT pin is isolated from the battery. This True−Cutoff function reduces the shutdown current to typically only 50 nA. Ring−Killer is also integrated to eliminate the high−frequency ringing in discontinuous conduction mode.

FEATUREs
• Pb−Free Package is Available
• High Efficiency: 94% for 3.3 V Output at 200 mA from 2.5 V Input
                            88% for 3.3 V Output at 500 mA from 2.5 V Input
• High Switching Frequency, up to 1.2 MHz (not hitting current limit)
• Output Current up to 600 mA at VIN = 2.5 V and VOUT = 3.3 V
• True−Cutoff Function Reduces Device Shutdown Current to
   typically 50 nA
• Anti−Ringing Ring−Killer for Discontinuous Conduction Mode
• High Accuracy Reference Output, 1.20 V ±1.5%, can Supply
   2.5 mA Loading Current when VOUT > 3.3 V
• Low Quiescent Current of 8.5 μA
• Integrated Low−Battery Detector
• Open Drain Low−Battery Detector Output
• 1.0 V Startup at No Load Guaranteed
• Output Voltage from 1.5 V to 5.0 V Adjustable
• 1.5 A Cycle−by−Cycle Current Limit
• Multi−function Logic−Controlled Shutdown Pin
• On Chip Thermal Shutdown with Hysteresis

Typical Applications
• Personal Digital Assistants (PDA)
• Handheld Digital Audio Products
• Camcorders and Digital Still Cameras
• Hand−held Instruments
• Conversion from one to two Alkaline, NiMH, NiCd Battery Cells to
   3.0−5.0 V or one Lithium−ion cells to 5.0 V
• White LED Flash for Digital Cameras