The ICS842S104 is a PLL-based clock generator specifically designed for PCI ExpressTM Clock Generation 2 applications. This device generates either a 200MHz or 100MHz differential HSTL clock from an input reference of 25MHz. The input reference may be derived from an external source or by the addition of a 25MHz crystal to the on-chip crystal oscillator. An external reference is applied to the XTAL_IN pin with the XTAL_OUT pin left floating.The device offers spread spectrum clock output for reduced EMI applications. An I2C bus interface is used to enable or disable spread spectrum operation as well as select either a down spread value of -0.35% or -0.5%.The ICS842S104 is available in a lead-free 24-Lead package.