Step-Down Converter With Linear Bypass Powers Multimode PAs In Mobile Handsets

SUNNYVALE, Calif., Feb. 16, 2011 (GLOBE NEWSWIRE) -- Maxim Integrated Products (Nasdaq:MXIM) introduces the MAX8989, a step-down converter designed to power PA (power amplifier) modules in mobile phones.

Note to Editor:

• The MAX8989 is a step-down converter optimized for powering multimode PA modules in cell phones and smartphones.
• This device reduces system cost by providing a single power supply for all PA modules in the system.
• The MAX8989 is the first PA DC-DC converter on the market to support multiple cellular and data communication protocols (LTE, WCDMA, GSM, and EDGE), making it ideal for use with converged (multimode) PAs.
• Targeted applications include mobile handsets and other battery-powered devices where efficiency is critical.

The first DC-DC converter in the industry to support power management for multiple communication protocols (e.g., LTE, WCDMA, GSM, and EDGE), the MAX8989 is ideal for converged (multimode) PAs. This solution is utilized in Infineon's proven SMARTi™ UE2 RF engine platform, which delivers unparalleled flexibility and efficiency to multistandard cellular phone systems.

The MAX8989 integrates a high-efficiency switching regulator with a parallel bypass LDO to guarantee maximum efficiency under all conditions. This approach enables designers to minimize the amount of power dissipated within the PA by regulating the PA's output stage supply voltage. By controlling the PA supply voltage to meet transmission-power requirements, designers can extend 2G talk time by up to 25% and 3G talk time by up to 10%.

The integrated LDO serves to smooth the transition between step-down regulation and operation in dropout, allowing for a seamless transition to higher power levels. When in dropout, the LDO becomes a low-impedance (85milliohm) bypass FET to ensure minimal power loss during periods of peak current demand. Additionally, the switching regulator is capable of a 100% duty cycle to further eliminate losses.