The ST1534A is designed for applications such as power managed PCI and network interface cards (NICs) where the 3.3V VAUX supply may be required when the 5V supply is shut down. During regular operation, the internal LDO regulator generates 3.3V power for the PCI card from the 5V supply. When the 5V VAUX is available, the IC connects this supply directly to its output using an external P-Channel FET, ensuring uninterrupted 3.3V output 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. This product is suitable for applications such as network interface cards, PCMCIA/PCI interface cards, desktop computers, and power supplies with multiple input sources.
The ST1534A LDO is designed for power‑managed PCI and network interface cards, providing a regulated 3.3 V output from a 5 V supply. It features automatic source selection, a gate‑drive for an external PMOS bypass switch, and a 5 V detector with hysteresis to ensure uninterrupted operation.
Key specifications include a guaranteed 500 mA output current, 3.3 V regulated output, operating temperature range 0 °C‑85 °C, and availability in P2PAK, PPAK and SO‑8 packages. The datasheet provides absolute maximum ratings, thermal data, pin descriptions, typical application circuits, and detailed electrical characteristics.