Maxim Integrated Products Inc. (Sunnyvale, CA) announced its new MAX8500, MAX8503 and MAX8504 step-down, dc/dc converter ICs, which have an input range from 2.6V to 5.5V and are designed for the linear power amplifiers used in 2.5G and 3G cellular phones. All three ICs operate at full duty-cycle and integrate a bypass FET, allowing operation directly from the battery at heavy loads. For light loads, the MAX8500 and MAX8503 utilize an LDO regulator to bypass the external inductor to eliminate switching losses.
Available in 4mm x 4mm x 0.8mm, 12-pin, QFN packages, the ICs deliver currents of up to 600mA and feature a switching frequency of 1MHz. The MAX8500 and MAX8503 can vary their output voltage from 0.4V to 3.4V in <30µs to improve efficiency by up to 47 percent. The MAX8504 is programmed for fixed 1.25V to 2.5V output with external resistors.
The ICs also feature a dropout of 150mV, draw a quiescent current of 280µA and drop to 0.1µA in logic-controlled shutdown. The devices are screened for operation over the extended temperature range.
