austriamicrosystems AS1339 step down regulator

austriamicrosystems has launched the AS1339 step down regulator, suitable for multiband WCDMA/NCDMA applications such as mobile handsets, wireless PDAs and smart phones.

The device delivers up to 650 mA from an input voltage range of 2.7 to 5.5, making it suitable for single Li-Ion cells.

Low power RF amplifiers can scale the output power dynamically by changing its supply voltage and the output voltage is dynamically controlled using an external analog input signal which has a gain of 2.5 V/V. The 30 µs settling time of the output voltage ensures CDMA specifications are not exceeded.

The device is designed for size-restricted applications such as mobile phones and other portable wireless end equipment. The 2 MHz fixed switching frequency allows the use of low-profile inductors and capacitors.

The device’s 97% peak efficiency boosts battery lifetime and supports 1.1 A peak current. The integrated 110 mΩ bypass FET provides maximum power with minimum dropout even under low-battery conditions. It enters bypass mode automatically during high power transmissions and also integrates two 10 mA low-noise, high-PSRR LDOs, making them suitable for PA biasing. Each LDO features a separate enable, providing high output voltage accuracy and requiring only 10 nF of output capacitance.

The device offers a 100 nA shutdown mode combined with an output disconnect feature, as well as soft start and current overload and thermal shutdown protection.