The ADP5303 is high efficiency, ultralow quiescent current step-down regulator that draws only 240 nA quiescent current to regulate the output at no load.The ADP5303 runs from an input voltage of 2.15 V to 6.50 V, allowing the use of multiple alkaline or NiMH cells, Li-Ion cells, or other power sources. The output voltage is selectable from 0.8 V to 5.0 V by an external VID resistor and a factory fuse. The total solution requires only four tiny external components.The ADP5303 can operate between hysteresis mode and PWM mode via the SYNC/MODE pin. In hysteresis mode, the regulator achieves excellent efficiency at less than 1 mW and provides up to 50 mA of output current. In PWM mode, the regulator produces a lower output ripple and supplies up to 500 mA of output current. The flexible configuration capability during operation of the device enables very efficient power management to meet both long battery life and low system noise requirements.The ADP5303 integrates an ultralow power comparator with a factory programmable voltage reference to monitor the input battery voltage. The regulator runs at a 2 MHz switching frequency in PWM mode and the SYNC/MODE pin can be synchronized to an external clock from 1.5 MHz to 2.5 MHz.Other key features in the ADP5303 include separate enabling, QOD, and safety features such as overcurrent protection (OCP), thermal shutdown (TSD), and input undervoltage lockout (UVLO).The ADP5303 is available in 9-ball, 1.65 mm × 1.87 mm WLCSP package rated for the −40°C to +125°C junction temperature range.ApplicationsEnergy (gas, water) meteringPortable and battery-powered equipmentMedical applicationsKeep-alive power supply