Maxim Introduces Buck Converter with Linear Bypass Mode

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Photocoupler

Maxim introduces the MAX8989, a step-down converter designed to power PA (power amplifier) ​​modules in mobile phones. The industry's first DC-DC converter to support power management for multiple communication protocols such as LTE, WCDMA, GSM and EDGE, the MAX8989 is ideal for integrated (multi-mode) PAs. The solution is now available on Infineon's proven SMARTiTM UE2 RF engine platform, providing unparalleled flexibility and efficiency for multi-standard cellular phone systems.

The MAX8989 integrates a high-efficiency switching regulator with a parallel bypass LDO to ensure maximum efficiency under all operating conditions. This solution greatly reduces PA power consumption by adjusting the PA output stage supply voltage. Designers can control the PA's supply voltage to meet transmit power requirements, extending 2G talk time by 25% and 3G talk time by 10%.

The built-in LDO is used to smooth the transition between buck regulation and low dropout operation for seamless switching to high power modes. When the voltage drops, the LDO is equivalent to a low-impedance (85mΩ) bypass FET that minimizes power dissipation during peak currents. In addition, the switching regulator is capable of operating at 100% duty cycle, further reducing losses.

The MAX8989 supports up to 2.5A of output current and is ideal for GSM/EDGE PA power supplies. The device operates over the -40°C to +85°C extended temperature range and is available in a compact (1.6mm x 1.6mm, maximum height 0.69mm), 9-bump wafer level package (WLP). Samples and evaluation boards are now available.