Global Sources
EE Times-Asia
Stay in touch with EE Times Asia
EE Times-Asia > Power/Alternative Energy
Power/Alternative Energy??

Power-management ICs target portable devices

Posted: 27 Nov 2006 ?? ?Print Version ?Bookmark and Share

Keywords:AnalogicTech? AAT2550? AAT2551? SystemPower? power management?

AnalogicTech's AAT2550 power-management IC

AnalogicTech has introduced a highly integrated power-management IC for smart phones, portable media/music players and other handheld computing devices. Targeted at portable systems powered by single-cell Li-ion/polymer batteries rated up to 1,500mAh, the AAT2550 saves PCB space by combining a 1A battery charger with two 600mA step-down converters in a small 4-by-4mm QFN package.

Digital thermal control
The new device features a digital thermal control loop in the battery charger that automatically reduces charge current when the demand on the power system exceeds its thermal limits. One of the challenges of squeezing three relatively high-powered blocks into a single small package is that if all three operate concurrently, they can generate more heat than the single package can handle. By integrating the company's digital thermal control loop into the battery charger, the AAT2550 senses when the IC is self-heating and automatically throttles back the battery charge current to decrease the power being dissipated without impacting the buck converters, thus preventing a processor interrupt or system shut-down. Moreover, by determining the highest level of charge current the system can maintain, this feature plays a major role in minimizing charge time, the company explained.

For systems that require charging from either AC or USB sources, the company is also introducing the AAT2551 SystemPower IC. Similar to the AAT2550, this device features a 1A charger and two 600mA buck converters. However, the charger in the AAT2551 offers dual-path AC adapter and USB charging. The USB path offers two user-programmable charge currents to support USB low and high charge levels.

Charge reduction function
The charger in the AAT2551 also adds the company's innovative charge reduction function that automatically reduces charge current only to the extent necessary to preserve the integrity of the USB host voltage. By allowing users to charge the battery with the maximum available current from the USB port while keeping the port voltage regulated, this feature ensures the battery charger will not overload the USB port even when other system applications share power with the port supply, and that the battery charge time is minimized. The AAT2551 will be available Q1 2007.

Both the AAT2550 and AAT2551 feature a constant current/constant voltage battery charger with the charge current programmable via an external resistor, from 100mA to 1A. The charger offers an integrated pass device, reverse blocking protection, high accuracy, digital thermal regulation, charge status and charge termination. It also adds overvoltage, overcurrent and thermal protection.

To help reduce the size of external components, the two 600mA step-down converters in the AAT2550/51 operate at a 1.4MHz switching frequency. Both devices operate off a 2.7-5.5V input and feature independent input, enable and feedback pins. Each converter consumes just 2?A of no-load quiescent current.

Both the AAT2550 and the AAT2251 are specified over the -40C to 85C temperature range. The AAT2550 is available in a Pb-free, thermally-enhanced QFN44-24 package, while the AAT2551 comes in a Pb-free, thermally-enhanced TQFN44-28 package.

Article Comments - Power-management ICs target portable...
*? You can enter [0] more charecters.
*Verify code:


Visit Asia Webinars to learn about the latest in technology and get practical design tips.

Back to Top