UM3503QA Datasheet | Union Semiconductor

Description The UM3503QA is a plete 1A, DC/DC step-down power supply intended for low-power applications. It is capable of delivering 1A output current over a wide input voltage range from 2.5V to 5.5V. Switching regulator, inductor and input/output capacitors are integrated into a tiny 4mm×4mm×1.05mm QFN package. Unless the external resistor divider, no additional ponents are required to acplish the design. The UM3503QA is engineered to simplify design and to minimize layout constraints. It is ideal replacement of discrete buck converter to save PCB space. The UM3503QA is based on a synchronous step-down DC-DC converter optimized for battery-powered portable applications. The DC/DC converter enters the pulse skipping mode automatically at light load condition. This can increase efficiency. The operation frequency is set to 2.25MHz at normal load condition. The UM3503QA enters shutdown mode and consumes less than 1µA when EN pin is pulled low. The UM3503QA is available in a pact and low profile QFN24 4.0mm×4.0mm×1.05mm package. Applications Features z LDO Replacement z FPGA and DSP Point-of-Load Regulator z Cellular and Smart Phones z MCU, DSP and FPGA Core Supplies z Wireless and DSL Modems z Portable Game Consoles and Instruments z PDAs, GPS z Bluetooth Headsets z Battery-Powered Devices z Ultra Small QFN Package 4.0×4.0×1.05 z High Efficiency: Up to 90% z 1A Output Current z 0.6V Minimum Output Voltage z 2.5V to 5.5V Input Voltage Range z 2.25MHz Switching Frequency z 56μA Quiescent Current z <1µA Shutdown Current z Excellent Load Transient and Line Transient z Pulse Skipping Mode Operation z Low Ripple at Light-Load Pulse Skipping Mode z Thermal Fault Protection Typical Application Circuit Light Load Efficiency VIN 2.5V to 5.5V PVIN AVIN VOUT VOUT 1.8V R1 360k O C1 22p F (Optional) Light Load Efficiency vs.Input Voltage 100 90 80 70 Ef f iciency (%) MODE FB R2 180k O ILOAD=1m A ILOAD=2m A 10 ILOAD=5m...