Boost Converter Suits USB-Port Applications

Feb 7, 2007 11:09 AM

Advanced Analogic Technologies’ AAT1275 is a 500-mA boost converter with a current-limiting load switch. By bringing together a regulated 5-V, 500-mA output with current-limit protection in a single monolithic device, the AAT1275 simplifies the development of host USB ports in portable systems powered from a single-cell Li-ion battery.

Operating from a 2.7-V to 5-V input range, the AAT1275 supports both USB 2.0 host port and USB on-the-go operation. While the load switch current limit defaults to the standard USB 500-mA limit, it can be programmed to lower values to host lower-current USB ports or support any application that requires a current-limited 5-V supply. The AAT1275 provides efficiency levels of greater than 90% across a wide load range. A 2-MHz switching frequency provides fast load transients and minimizes the size of external components.

One of the most difficult challenges designers face using conventional boost converters is leakage current. To address this problem, the AAT1275 adds an innovative "true load disconnect" feature that minimizes losses and simplifies design by isolating the load from the power source when the device is off.

The integrated programmable current limiting load switch on the IC also provides USB port protection. An active-low fault flag alerts the system when an overcurrent condition is applied to the output.

The AAT1275 is available in 2.75-mm x 3-mm 12-pin TSOPJW or 16-pin TDFN34 packages. The device sells for $1.75 each in 1000-piece quantities.