National Semiconductor claims 'first' flexible PMU

National Semiconductor Corp. claimed it has developed the first flexible power management unit (PMU) with an integrated buck-boost converter to its family of digitally programmable, multiple-output power management devices.

Suitable for energy-sensitive portable media applications, the LP3910 features a high-current buck-boost converter that enables longer run times than traditional buck converters. In addition, the LP3910 includes a dual-source battery charger to power a device from a wall adapter or USB and a digital I?C compatible interface. The integrated battery charger supports power routing, which allows system usage immediately after an external power source has been detected. The I?C interface allows design engineers to customize electrical specifications such as output voltage and switching modes to the end application. The digital interface provides the flexibility to use the same device for multiple solutions that require different output voltages.

In portable media players where mini-HDDs typically require a 3.3V supply, a buck-boost converter extends battery life. Li-ion batteries, a popular choice for portable media players, have an operating voltage range of 2.9-4.2V. When the Li-ion battery is fully charged, the converter steps the voltage down to supply the HDD. When the battery voltage is lower than 3.3V, the converter steps up the voltage. This technique increases the run-time of the player up to 10 percent over the run-time achieved by a traditional buck converter.

96% efficiency
The LP3910 includes two buck regulators that provide up to 96 percent efficiency. Power consumption is further minimized through a dynamic voltage-scaling feature that enables the device to adjust or scale the output voltage in real time to match the computing workload and clock frequencies of the corresponding processors. The end result is longer battery life in energy-sensitive systems such as personal media players.

Available in a small, 48-pin LLP package that measures 6-by-6mm, the LP3910 is a programmable system PMU that is optimized for portable media players with HDDs. It incorporates two low-dropout (LDO) voltage regulators, two integrated buck converters with dynamic voltage scaling, a wide-load-range buck-boost converter with programmable output voltage, a 4-channel, 8bit ADC for managing the battery usage and a dual-source Li-ion/polymer battery charger. The charger has the capability to charge and maintain a single-cell battery from a regulated wall adapter or USB power.

For applications using flash memory or products without a hard drive, National offers the LP3913 with the same features as the LP3910, but a 500mA buck converter replaces the buck-boost converter.

Available today, the LP3910 is priced at $4.84 and the LP3913 is $4.40 each in 1,000-unit quantities.