DESCRIPTION
Low operating supply current (typ 200µA) make the device ideal for small, portable and battery powered applications. When shut down the load is disconnected from the input and the supply current is typically 0.02µA. The ST619LB is available in SO-8 and DIP-8 packages. SCHEMATIC DIAGRAM May 2001 1/9 ST619LB SERIES OPERATING PRINCIPLE The ST619LB is able to provide a regulated 5V output from a 2V to 3.6V (two battery cells) input. Internal charge pump and external capacitors generate the 5V output, eliminating the need for inductors. The output voltage is regulated to 5V, ±4% by a pulse skipping controller that turns on the charge pump when the output voltage begins to drop. To maintain the greatest efficiency the internal charge pump of the device operates as a voltage doubler when VI ranges from 3.0V to 3.6V and as a voltage tripler when VI ranges from 2.0V to 2.5V. When VI ranges from 2.5V to 3.0V , the ST619LB switches between doubler and tripler mode on alternating cycles, making a 2.5 x VI charge pump.
STMicroelectronics
