MAX1857

19-1812; Rev 0; 1/01 500mA, Low-Dropout, Ripple-Rejecting LDO in µMAX General Description The MAX1857 low-dropout linear regulator operates from a +2.5V to +5.5V supply and delivers a guaranteed 500mA load current with low 120mV dropout. The high-accuracy (±1%) output voltage is preset at an internally trimmed 4.75V or can be adjusted from 1.25V to 5.0V with an external resistive divider. An internal PMOS pass transistor allows the low 135µA supply current to remain independent of load, making this device ideal for portable battery-operated equipment such as personal digital assistants (PDAs), cellular phones, cordless phones, base stations, and notebook computers. Other features include an active-low open-drain reset output with a 4.5ms timeout period that indicates when the output is out of regulation, a 0.1µA shutdown mode, short-circuit protection, and thermal shutdown protection. The device is available in a miniature 8-pin µMAX package. For higher power applications, refer to the MAX1792 and MAX1793 data sheets. o Guaranteed 500mA Output Current o Low 120mV Dropout at 500mA o Up to ±1% Output Voltage Accuracy Preset at 4.75V Adjustable from 1.25V to 5.0V o Reset Output with 4.5ms Timeout Period o Low 135µA Ground Current o 0.1µA Shutdown Current o Thermal Overload Protection o Output Current Limit o Tiny µMAX Package Features MAX1857 ________________________Applications Notebook Computers Cellular and Cordless Telephones PDAs Palmtop Computers Base Stations USB Hubs...