There are three different types of sequencing or startup techniques: Simultaneous, Ratiometric, and Sequential. In simultaneous sequencing the core voltage will track the IO voltage until either supply reaches the final value. Simultaneous sequencing is generally preferred for powering most DSPs and FPGAs. In many of these processors there are parasitic conduction paths from the Vcore pins to the IO pins. If these parasitic paths conduct during power-on, the device may not power-up correctly and could be damaged. Since in simultaneous sequencing the core voltage tracks the IO voltage, there is no chance of forward biasing any of these parasitic conduction paths. Ratiometric sequencing is useful in applications where both supplies need to be at the final value at the same time. The last method, sequential sequencing, starts the different voltage rails one after another at a specific time. It is the most utilized method of sequencing and is good for minimizing startup stress on the input bus. Also, many systems require power to be applied in a specific order for proper initialization.