Maxim Releases Dual Buck Converter for Powering 3G PA and RF Transceivers
Maxim Integrated Products introduced the MAX8896, a dual step-down converter designed for powering WCDMA/NCDMA PA (power amplifier) modules and RF transceivers. This 4mm² device integrates a high-efficiency, PA step-down converter that is optimized for medium- and low-power transmission, and includes a bypass FET for powering the PA directly from the battery during high-power transmission. By using the MAX8896 between the battery and RF-transceiver/PA, designers can reduce current consumption by up to 50% under typical operating conditions, thus extending battery life.
The MAX8896 also includes an RF step-down converter that supplies a high-PSRR, low-noise LDO (low-dropout linear voltage regulator) to provide a high-efficiency voltage supply for the RF transceiver. The MAX8896 is well suited for multiband WCDMA/NCDMA applications such as cellular handsets, netbooks, and smartphones. The MAX8896 is available in the Infineon® SMARTi™ UE HSPA RF transceiver and the XMM™ 6160 mobile phone platform, providing users with best-in-class battery life.
Supporting 1.9A of peak current, the integrated low-impedance 140mΩ (typ) bypass FET provides maximum power with minimum dropout, even under low-battery conditions. During high-power transmission, the bypass FET automatically turns on if the required output voltage is within 99% of the input voltage, and the PA step-down converter is forced into a 100% duty cycle.
The RF step-down converter has 94% peak efficiency with a 2MHz fixed switching frequency. It supports a 100% duty cycle, and provides a fixed 3.1V output voltage with ±2% output-voltage accuracy. The high-PSRR (65dB), low-noise (16microVrms), 2.8V LDO delivers a guaranteed 200mA output current. The low-noise output makes this LDO well suited for RF transceiver biasing or applications that require an exceptionally clean power source.
The MAX8896 is offered in a tiny, 2 x 2mm, 16-bump UCSP™ package (0.7mm height, max) and is fully specified over the -40 to +85°C extended temperature range. Prices start at $1.92 (2500-up, FOB USA).
