Tiny DC-DC Converter Powers 3G Handsets

Intended for designers of 3G handsets and wireless data cards, the FAN5902 is an RF-power DC-DC converter packaged in a 12-bump, 0.5-mm-pitch CSP package. The device operates at 6 MHz with a reduced-size 0.5-µH chip inductor, saving space and component costs. This converter helps to extend talk-time by up to 40 minutes in 3G handsets by adapting the voltage supply level of the 3G RF power amplifier according to the RF power sent through the antennas, enabling higher power efficiency for a wide range of antenna power levels. This results in a savings of up to 100 mA of battery current consumption in data-centric and smart phones, especially in poor coverage areas. This feature dramatically extends connection times and allows 3G handsets to run more processor applications. In addition, the FAN5902 offers up to 800 mA rms current output capability to service excessive RF PA current resulting from strong antenna mismatch and a 50-m? on-resistance bypass FET, enabling operation down to 2.7 V. The FAN5902 also addresses the key problem of overheating in the RF power amplifier, especially at high battery voltage. Because the FAN5902 scales down the RFPA supply voltage, reducing its heating by 20 to 40%, the heat sink can be shrunk and the component density can be increased, reducing weight, cost and size. Pricing is $0.75 each in lots of 1000 with samples available now. Delivery is from stock. FAIRCHILD SEMICONDUCTOR, San Jose, CA. (408) 822-2000.