Advanced Analogic Technologies Incorporated (AnalogicTech) (Nasdaq: AATI), a developer of power management semiconductors for mobile consumer electronic devices, announced the AAT2789, a new dual buck converter for mobile consumer and wireless applications. Operating from 2.7V to 5.5V input range, the AAT2789 2-channel synchronous step-down converter is designed for portable systems powered from a single-cell Lithium-ion battery or consumer equipment using a 3.3V or 5V bus. Integrating both a high current 1.7A buck converter with a low current 800mA buck converter, the new device consolidates power management functions for a wide variety of WLAN products, GPS devices, Smart Phones, Portable Media Players and other handheld devices. The AAT2789 also features a high switching frequency which helps minimize external filter size. Peak current mode control eliminates the need for external compensation while optimizing transient performance and stability. To ensure the integrity of the device, the AAT2789 features integrated soft start to limit inrush current. For overload conditions, the device adds over-temperature and current limit protection circuits.

The dual converter features one channel which delivers up to 1.7A and a second channel which supplies up to 800mA. Both converter channels use a unique low noise architecture developed by AnalogicTech to minimize output ripple and spectral noise. Each converter also uses its own independent enable pin. Output voltage is externally adjustable. Channel 1 delivers up to 1700mA output current while Channel 2 delivers up to 800mA. Both converters incorporate a unique low noise architecture which reduces output ripple and spectral noise. The AAT2789 uses a high switching frequency to minimize external filter sizing. Peak current mode control eliminates external compensation while optimizing transient performance and stability. The AAT2789 requires a minimum of external components to realize a high efficiency dual-output step-down converter while minimizing solution size and footprint.

The device utilizes a high switching frequency to minimize external filter sizing. Peak current mode control eliminates external compensation while optimizing transient performance and stability. The device requires a minimum of external components to realize a high efficiency dual-output step-down converter while minimizing solution size and footprint. Each of the step-down regulators has an independent input and enable pin. Adjustable output voltage is provided. Light load operating mode provides high efficiency over the entire load range. The enable inputs, when pulled low, force the respective converter into a low power non-switching state consuming less than 1μA of current. Low quiescent current enables excellent life for battery powered systems. Additional features include integrated soft start to limit inrush current. Soft start limits the current surge seen at the input and eliminates output voltage overshoot. For overload conditions, the peak input current is limited. Also, over-temperature protection safeguards the device from damage due to high operating temperature or fault conditions. The junction over-temperature threshold is 140°C with 15°C of hysteresis. Under voltage lockout (UVLO) guarantees sufficient input voltage bias prior to turn-on.

Many mobile consumer electronics systems require more than 1.5A to power the system microprocessor and less current to power the baseband processor, memory or I/O.,. By combining two optimally sized step-down converters in a single 3×4-mm package, the AAT2789 provides designers with efficient power conversion in a form factor designed to reduce system cost and provide a 25% reduction in board space. The AAT2789 is a 2-channel synchronous step-down converter operating from an input voltage range of 2.7V to 5.5V, making it the ideal choice for single-cell Lithiumion/ polymer battery powered systems or low voltage 3.3V and 5V based consumer equipment.

Both step-down converters use peak current mode control with slope compensation to maintain stability for duty cycles greater than 50%. When the duty cycle exceeds 50%, the inductor value must be selected to maintain the prescribed down-slope in accordance with the internal slope compensation requirements.There are three types of losses associated with the AAT2789 step-down converter: switching losses, conduction losses, and quiescent current losses. Conduction losses are associated with the RDS(ON) characteristics of the power output switching devices. Switching losses are dominated by the gate charge of the power output switching devices.

Low RDS(ON) power switches help improve power efficiency at high current levels. To further extend battery life, the device adds a low quiescent current, light load operating mode which maximizes power efficiency over the entire load range.

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