Step-down converter targets multimode PAs

Maxim Integrated Products has released a DC-DC converter that could extend battery life and talk time in mobile products. The MAX8989 is designed for multimode (converged) power amplifier (PA) modules. It also supports power management for multiple communication protocols such as LTE, WCDMA, GSM and Edge. It uses a high-efficiency switching regulator with a parallel bypass low dropout regulator (LDO), allowing designers to minimize the amount of power dissipated within the PA by its output stage supply voltage. With this setup, Maxim claims 2G talk time can be extended by up to 25 percent and 3G talk time by up to 10 percent.

The integrated LDO serves to make a smooth transition between step-down regulation and operation in dropout. When in dropout, the LDO becomes a low-impedance (85mΩ) bypass FET to ensure minimal power loss during periods of peak current demand. Additionally, the switching regulator's 100 percent duty cycle could further eliminate losses.

The MAX8989 supports up to 2.5A, making it compatible with GSM/Edge PAs. It is fully specified over -40°C to +85°C extended temperatures and offered in a 1.6mm × 1.6mm, 0.69mm max height, nine-bump wafer-level package.

Maxim's DC-DC converter is currently being used by Infineon's SMARTi UE2 RF engine platform. Prices for the converter start at $1.92 (1000-up, FOB USA).