Maxim Integrated Products’ MAX8581/MAX8582 high-efficiency, stepdown dc-dc converters are capable of switching at 2.5 MHz, while the MAX8582 also runs at 1.5 MHz for lower switching losses. The devices can continuously deliver 600 mA and integrate a 65-mΩ FET. During high-power transmission, this bypass FET connects the power amplifier (PA) directly to the battery with a dropout of 33 mV at 500 mA, thus minimizing power loss at the inductor and allowing minimal battery voltage for device usage.
To maximize PA efficiency, the output can be dynamically varied from 0.4 V to VIN, depending on the distance to the base station and the desired transmission mode (voice or data). This flexibility improves efficiency by 47% at +10 dBm. Consequently, handset designers can almost double talk-time and/or reduce battery size.
Both devices are optimized for use with a small, low-cost inductor and small ceramic capacitors. The MAX8581/MAX8582 are packaged in a 3-mm x 3-mm x 0.8-mm, 10-pin TDFN and are specified over the extended temperature range.