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)
applications
ldigital cameras and mp3
lpalmtop computers / pdas
lcellular phones
lpc cards
lportable media players