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ST778

ST Microelectronics
Part Number ST778
Manufacturer ST Microelectronics
Description (ST777 - ST779) ADJUSTABLE OUTPUT DC-DC CONVERTER
Published Dec 13, 2006
Detailed Description www.DataSheet4U.com ST777/778/779 LOW VOLTAGE INPUT, 3-3.3V/5V/ADJUSTABLE OUTPUT DC-DC CONVERTER WITH SYNCHRONOUS RECTI...
Datasheet PDF File ST778 PDF File

ST778
ST778

Overview
www.
DataSheet4U.
com ST777/778/779 LOW VOLTAGE INPUT, 3-3.
3V/5V/ADJUSTABLE OUTPUT DC-DC CONVERTER WITH SYNCHRONOUS RECTIFIER s s s s s s s s s 1V TO 6V INPUT GUARANTEES START-UP UNDER LOAD MAXIMUM OUTPUT CURRENT OF 300mA (778 OR 779 ADJUSTED TO 3V) LOAD FULLY DISCONNECTED IN SHUTDOWN TYPICAL EFFICIENCY OF 82% INTERNAL 1A POWER SWITCH AND SYNCHRONOUS RECTIFIER ADJUSTABLE CURRENT LIMIT ALLOWS LOW-COST INDUCTORS SUPPLY CURRENT OF 270µA (NO LOAD) SHUTDOWN SUPPLY CURRENT 20µA PACKAGE AVAILABLE: DIP-8 AND SO-8 DIP-8 SO-8 DESCRIPTION The ST777/778/779 are dc-dc converters that step-up from low voltage inputs requiring only three external components, 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 VIN 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 2 IN DELAY TIMER 1 5 ILIM LX ACTIVE RECTIFIER tOFF SWITCH DRIVER DELAY TIMER OUT 6 VO 100µF tON 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...


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