ST777 Datasheet | STMicroelectronics

SCRIPTION The ST777/778/779 are dc-dc converters that step-up from low voltage inputs requiring only three external ponents, an inductor (typically 22µH) and two capacitors. The device include a Sinchronous Rectifier that eliminates the need for an external catch diode, and allows regulation even when the input is greater than the output. SCHEMATIC DIAGRAM 100µF Unlike others step-up DC-DC converters the ST777/778/779’s Sinchronous Rectifier turns off in the shutdown mode, fully disconnecting the output from the source. This eliminates the current drain associated with conventional step-up converters when off or in shutdown. Supply current is 270µA under no load and only 20µA in stand by mode. 22µH RLIM DELAY TIMER ILIM ACTIVE RECTIFIER t OFF SWITCH DRIVER DELAY TIMER OUT 6 100µF t ON 1 : N RECTIFIER CONTROL PGND 4 SEL 8 VREF 1.25V 7 SHDN SHUTDOWN CONTROL AGND 3 October 2002 1/11 ST777/778/779 ABSOLUTE MAXIMUM RATINGS Symbol VCC LX OUT, SHDN AGND to PGND FB PTOT TSTG TOP Parameter DC Input Voltage to GND Switch off Pin Voltage Switch on Pin Voltage Output, Shutdown Voltage Analog and Power Ground FB Pin Voltage Continuous Power Dissipation (at TA = 85°C) DIP-8 Continuous Power Dissipation (at TA = 85°C) SO-8 Storage Temperature Range Operating Ambient Temperature Range Value -0.3 to +7 -0.3 to +7 30 sec short to IN or OUT -0.3 to +7 -0.3 to +0.3 -0.3 to (OUT+0.3) 550 344 -40 to 150 0 to 85 Unit V V V V V m W °C °C Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. ORDERING CODES TYPE ST777 ST778 ST779 DIP-8 ST777ACN ST778ACN ST779ACN SO-8 ST777ACD ST778ACD ST779ACD CONNECTION...