The UTC UR5516 is designed to provide a regulated voltage with bi-directional output current for DDR-SDRAM termination. Current-limit work to limit the short-circuit current, on-chip thermal shutdown provides protection against any combination of overload that would create excessive junction temperature. The output voltage tracks the voltage at VREF pin. A resistor divider connected to VIN, GND and VREF pins is used to provide a half voltage of VIN to VREF pin. In addition, an external ceramic capacitor and an open-drain transistor connected to VREF pin provides soft-start and shutdown control respectively. Pulling and holding the VREF to GND shuts off the output. The output of UTC UR5516 will be high impedance after being shut down by VREF or thermal shutdown function.