National Semiconductor has introduced its smallest 4MHz synchronous step-down DC-DC converter that provides up to a 1A output current over an input voltage range of 2.3V to 5.5V.

The LM3691 features peak efficiency of 95%, low quiescent current and output voltage precision of +/-1% to power baseband and next-generation applications processors.

It is offered in a micro SMD package and features high switching frequency up to 4MHz that enables use of miniature 1µH multilayer inductors and 4.7µF capacitors. Several fixed output voltage options are also available.

Transient performance is specified at ±40mV for stable output voltages. An integrated mode-control pin allows the design engineer to select forced pulse-width modulation (PWM) mode or auto mode, which changes modes between economy or ECO (gated PWM mode) and PWM automatically, depending on the load.

In ECO mode, the chip has a quiescent current at 63µA under light load conditions.  

See http://www.national.com/powerwise