The R5523N is CMOS-based high-side MOSFET switch IC for Universal Serial Bus (USB) applications. Low ON Resistance (Typ. 130m) and low supply current (Typ. 20A at active mode) are realized in this IC. An over-current limit circuit, a thermal shutdown circuit, and an under voltage lockout circuit are built-in as protection circuits. Further, a delay circuit for flag signal after detecting over-current, is embedded to prevent miss-operation of error flag because of inrush current. The R5523N is ideal for applications of protection for USB power supply. Since the package is small SOT23-5, high density mounting on board is possible.