Renesas also offers clock multiplexers with and without a PLL. These parts can be used in applications where there is a desire to switch from a local oscillator to a master system clock, like a PCI. The ICS580-01 will manually switch between the clock inputs, and the ICS580-02 will automatically switch with no glitches on the output. If zero delay is required, Renesas offers the ICS581-01-02 with an integrated PLL.