GENERALDESCRIPTION

The PW2057 is a constant frequency, currentmode step-down converter. The device integrates a main switch and a synchronousrectifier for high efficiency without an external Schottky diode. It is idealfor powering portable equipment that runs from a single cell Lithium-Ion (Li+)battery. 100% duty cycle capability extends battery life in portable devices,while the quiescent current is 200μA with no load, and drops to <1μA in shutdown.

FEATURES

l  High Efficiency: Up to 95%

l  1.0MHz Frequency Operation

l  2.2V to 5.5V Input Voltage Range

l  Current Mode Operation for ExcellentLine and Load Transient Response

l  Low Quiescent Current: 200μA

l  Output Voltage: 3.3V， 1.8V， 1.2V

l  Automatic PWM/PFM Mode Switching

l  No Schottky Diode Required

l  Short-Circuit Protection

l  Shutdown Quiescent Current: < 1μA

l  Low Profile SOT-23-5L Package(lead-free)