Description
ACE7551U is a high-efficiency pulse-width-modulated (PWM) step-down DC-DC converter, capable of
delivering 600mA output current over a wide input voltage range from 2.5V to 5.5V. The target application
of ACE7551U is for portable electronic devices that are powered from 1-cell Li-ion battery or from other
power sources within the range such as cellular phones, PDAs and handy-terminals. Internal
synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. No external
Schottky diode is required in practical application. The ACE7551U automatically turns off the
synchronous rectifier while the inductor current is low and enters discontinuous PWM mode. This can
increase efficiency at light load condition.
ACE7551U enter shutdown mode and consumes less than 0.1uA when EN pin is pulled low. The
operation frequency is set to 1.2MHz. This along with small SOT-23-5 package and DFN2*2-6L package
provides small PCB area application. Other features include lower internal reference voltage with 2%
accuracy, over temperature protection, and over current protection.

Features
⚫ High Efficiency: Up to 90%
⚫ 1.2MHz Constant Switching Frequency
⚫ 600mA Output Current
⚫ Integrated Main Switch and Synchronous Rectifier. No Schottky Diode Required
⚫ 2.5V to 5.5V Input Voltage Range
⚫ Low Quiescent Current: 50µA
⚫ Thermal Fault Protection
⚫ <1µA Shutdown Current
⚫ Lead Free SOT-23-5 Package and DFN2*2-6L Package

Application
⚫ Cellular and Smart Phones
⚫ Microprocessors and DSP Core Supplies
⚫ Wireless and DSL Modems
⚫ PDAs, GPS
⚫ MP3 Player
⚫ Portable Instruments