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.

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.

■ 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