DC/DC convertors shrink to chip-scale packages

More compact packaging option also reduces noise compared with traditional packaging with bond wires.

By taking advantage of lower component profiles, reduced stray inductance, capacitance and resistance and enhanced electrical characteristics, convertors using chip scale packaging (CSP) from AnalogicTech enable designers of cellphones, Bluetooth headsets and other space-constrained portable systems to reduce footprint, improve AC performance, and drive down manufacturing costs.

The use of CSP for its AAT1149 and AAT1171 DC/DC convertors eliminates bond wires and offers a dramatic reduction in footprint.

The packaging option also reduces noise compared with traditional packaging with bond wires.

CSP has quickly evolved from an interesting packaging innovation to a mainstream packaging technology, and the space savings offered are dramatic.

The AAT1149 was originally introduced in a 2 x 2.1mm 8-pin SC70JW package.

At 1.235 x 0.91mm, the CSP option reduces the required PCB footprint by 73%.

Similarly, the AAT1171, originally introduced in a 3 x 3mm 12-pin TDFN package, is now available in a CSP that, at 1.5 x 2.2mm, reduces the required PCB footprint by 64%, when compared with the original package.

Targeted at meeting tight portable design space requirements, the AAT1149 step-down convertor delivers up to 400mA of load current from a 2.7 to 5.5V input while operating with low-profile 1mm-high 0603 inductors.

Output voltage is programmable via external feedback resistors from 1.0V to input level.

The device attains up to a high 98% efficiency.

No load quiescent current is only 45uA.

The AAT1171 is a dynamic voltage-scaling DC/DC convertor optimised to support power amplifiers in WCDMA and CDMA handsets.

Operating across a wide 2.7 to 5.5V input voltage range, the device delivers up to 600mA of continuous load current.

The convertor optimises PA efficiency at both low and high transmit levels by supplying a variable output voltage of 0.6 to 3.6V.

No load quiescent current is only 45uA.

Using an AAT1171 step-down convertor can result in a 60% power savings when compared with connecting the PA directly to the system battery and thereby dramatically increase the talk-time of the mobile handset.

Both the AAT1149 and AAT1171 are qualified across the -40 to +85C temperature range.

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