DESCRIPTION
The ST1534A is intended for application such as power managed PCI and network interface cards
(NICs), where operations from 3.3V VAUX supplymay be required when the 5V supply has been shut down. During regular operation, 3.3V power for the PCI card is provided by the internal LDO regulator, generated from 5V supply. When the 5V VAUX is available, the IC connects this supply directly to its output using an external P-Channel FET. This ensures an uninterrupted 3.3V out even if VIN falls out of specification. When both supplies are available simultaneously, the drive pin DR will be pulled high, turning off the PMOS switch.

■ GLITCH FREE TRANSITION BETWEEN INPUT SOURCES
■ INTERNAL LOGIC SELECTS INPUT SOURCE
■ GATE DRIVE FOR EXTERNAL PMOS BYPASS SWITCH
■ 5V DETECTOR WITH HYSTERESIS
■ 1% 3.3V REGULATED OUTPUT VOLTAGE
■ 500mA GUARANTEED OUTPUT CURREN
■ OPERATING TEMPERATURE RANGE FROM 0°C TO 85°C
■ AVAILABLE IN P2PAK PACKAGE
■ PPAK AND SO-8 PACKAGES CAN BE AVAILABLE ON REQUEST