New Industry Products

National Semi Introduces Small Synchronous Step-Down DC-DC Converter For Portable Applications

June 08, 2008 by Jeff Shepard

National Semiconductor Corp. introduced what it describes as the industry’s smallest 4 MHz synchronous step-down dc-dc converter that provides up to a 1A output current over an input voltage range of 2.3 to 5.5V. The LM3691 dc-dc converter is said to be optimized for powering high-performance processors from a single Li-Ion cell battery in mobile phones, personal media players and other mobile devices.

A member of National’s PowerWise® energy-efficient product family, the LM3691 features peak efficiency of 95%, low quiescent current to maximize battery life and output voltage precision of ±1% to power baseband and next-generation applications processors.

The LM3691 dc-dc converter is offered in a micro SMD package and features high switching frequency up to 4 MHz that enables use of miniature 1µH multilayer inductors and tiny 4.7µF capacitors for a solution size of less than 15mm². Several fixed output voltage options are also available.

The LM3691 dc-dc converter features what is described as excellent transient performance of ±40 mV 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 LM3691 offers what is described as superior efficiency and very low quiescent current at 63µA under light load conditions. ECO mode extends the battery life through reduction of the quiescent current during light load currents and system standby. The LM3691 is offered in a 6-pin, 1.26 x 1.56mm micro SMD package.

The LM3691 is priced at $2.25 each in 1,000-unit quantities.