General Description G5309 is a 10A, synchronous DC/DC buck converter with integrated 20mΩ N-channel high-side MOSFET and 8.5mΩ N-channel low-side MOSFET. It uses constant on-time control scheme to handle wide input/ output voltage ratios with ease and provides 100ns “instant-on” response to load transients while maintaining a relatively constant switching frequency. The G5309 achieves high efficiency at a reduced cost by eliminating the current-sense resistor found in traditional current-mode PWMs. Single-stage buck conversion allows these devices to directly step down high-voltage batteries for the highest possible efficiency. The built-in 5V LDO supports 20mA for internal circuits. The G5309 is intended for the main power supply of LCD TV, Notebook Computer, or other low-voltage supplies as low as 0.75V. The G5309 is available in QFN4X4-28 and QFN5X5-32 package.