Fujitsu 6MHz buck-boost DC/DC converter extends mobile device battery life with minimum footprint

SUNNYVALE, USA: Fujitsu Semiconductor America Inc. (FSA) announced the Fujitsu MB39C326 power management IC (PMIC), a high-efficiency buck-boost DC/DC converter that operates at an industry-leading 6MHz. Fujitsu will introduce the new low-noise, synchronous converter during the Mobile World Congress. Samples will be available in June 2011.

The Fujitsu MB39C326 PMIC is designed to power the radio frequency power amplifiers (RFPAs) in mobile handsets and other mobile products that use a single-cell Li-ion battery. The converter switches at 6MHz compared with the 2 to 3MHz or lower switching rates of conventional converters, enabling designers to use a smaller inductor. The result is a reduction of up to 50 percent in the overall board space of the power management circuits.

The buck-boost functionality of the Fujitsu MB39C326 PMIC prolongs battery life and efficiency. When a Li-ion battery is fully charged, it starts with a high operating voltage. As the Li-ion battery is discharged, its operating voltage declines to the point at which the battery cannot provide sufficient power to its host device even if some charge remains.

The MB39C326 switches automatically between a buck operation (stepping down the voltage) when the battery is fully charged and a boost operation (stepping up the voltage) as the battery is discharged, which maximizes the battery's overall operating voltage and provides a stable power supply to the power amplifier. The result is a more consistent voltage level and a mobile device that can operate longer on a single charge.

"The market for mobile and smart phones, e-book readers, and other handheld mobile devices is demanding higher application performance and higher data transfer rates in the smallest form factor possible," said Akio Nezu, senior manager of marketing, Fujitsu Semiconductor America. "To meet this demand, manufacturers are aggressively trying to miniaturize components and reduce board space without impacting performance. Typically, one of the largest components is the passive inductor.

As the Fujitsu MB39C326 buck-boost DC/DC converter operates at an industry-leading 6MHz, manufacturers can use a much smaller inductor. This cuts the board space requirements for the power management circuits by as much as half, while increasing battery life and efficiency."

The Fujitsu MB39C326 PMIC provides up to 800mA of output current over an input voltage range of 3.1V to 4.6V. The device features a built-in, internal, field-effect transistor (FET); over-temperature protection; and an input-under-voltage lockout. The MB39C326 is available in a 20-pin, 0.4mm-ball-pitch, 2.15mm x 1.94mm WL-CSP (wafer level chip size) package.