AN2603 Datasheet, PDF (1/23 Pages) STMicroelectronics – ST1S09 high efficiency synchronous buck converter

AN2603
Application note
ST1S09 high efficiency synchronous buck converter
Introduction
The ST1S09 family of synchronous step-down DC-DC converters is optimized for powering
all low-voltage applications and, generally, to replaces high current linear solutions when
power dissipation may cause high heating of the application environment. It provides up to 2
A over an input voltage range of 2.7 V to 5.5 V.
A high 1.5 MHz switching frequency allows the use of tiny surface-mount components, and
in addition to the resistor divider to set the output voltage value, an inductor and two
capacitors are required. A low output ripple is guaranteed by the current mode PWM
topology and by the use of low ESR surface-mount ceramic capacitors.
The device is available in two versions: the ST1S09 with Power Good function and the
ST1S09I with an Inhibit function.
The device is thermally protected and current limited to prevent damage due to accidental
short circuit.
The ST1S09 family is available in the DFN6 3x3 package.
Figure 1. Simplified schematic
Note: 1 Available only for the ST1S09I
2 Available only for the ST1S09
February 2011
Doc ID 13778 Rev 3
1/23
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