ICS914817

The ICS914817 generates all clocks required for high speed RISC or CISC microprocessor systems such as Intel PentitunPro or Cyrix. Eight different reference Hequency multiplying factors are externally selectable with smooth frequency transitions. Features include four CPU, six PCI, two AGP (=2xPCI) and Twelve SDRAM clocks. Two reference outputs are available equal to the crystal frequency. One 48 MHz for USB, and one 24 MHz clock for super IO. Built in +-1.5%, 0.6% center or down spread spectrum modulation to reduce EMI. Serial programming I2C interface allows changing functions, stop clock programing and frequency selection. Additionally, the device meets the Pentium power-up stabilization, which requires that CPU and PCI clocks be stable within 2ms after power-up. High drive PCICLK and SDRAM outputs typically provide greater than 1 V/ns slew rate into 30pF loads. CPUCLK outputs typically provide better than 1V/ns slew rate into 20pF loads while maintaining 50t5% duty cycle. The REF and 24 and 48 MHZ clock outputs typically provide better than 0.5V/ns slew rates.

The features of ICS914817 can be summarized as (1)3.3V outputs: SDRAM,AGP, PCI, REF, 48/24 MHz; (2)2.5V or 3.3V outputs: CPU; (3)20 ohm CPU clock output impedance; (4)20 ohm PCI clock output impedance; (5)CPU to PCI skew I 2 to 6ns; (6)no external load cap for CLII 8pF crystals; (7)250 ps max CPU, PCI clock skew; (8)smooth CPU frequency transition among all CPU frequencies; (9)I2C interface for programming; (10)2ms power up clock stable time; (11)Clock duty cycle; (12)48 pin 300 mil SSOP package; (13)3 .3V operation, 5V tolerant inputs.

The absolute maximum ratings of ICS914817 are (1)supply voltage: 7.0V; (2)logic inputs: GND -0.5 to VDD +0.5V; (3)ambient operating temperature: 0°C to +70°C; (4)storage temperature: -65°C to +150°C (stresses above those listed Lmder absolute maximum ratings may cause permanent damage to the device. These ratings are stress specifications only and functional operation of the device at these or any other conditions above those listed in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect product reliability).