MK1449B

MK1449B Sound/SCSI+Fast Ethernet Clock Description The MK1449B is the most cost effective way to generate high quality, high frequency clock outputs for SCSI plus Fast Ethernet devices, or AC97 sound chips. Using Phase-Locked-Loop (PLL) techniques, the device uses a standard fundamental mode, inexpensive 14.31818 MHz crystal or clock to produce two output clocks. The device can accept either a crystal or clock input. Also on the chip is the ability to generate a 1.25x clock of the reference plus the reference, making it possible to generate 20 and 25 MHz clocks from a 20 MHz crystal. Features Packaged as 8 pin SOIC For Fast Ethernet plus SCSI on computer motherboards For AC97 sound on computer motherboards Less than 1 ppm synthesis error Input crystal frequency of 14.31818 MHz Operating voltages of 3.0 to 5.5V Available in industrial temperature Full CMOS level outputs with 25mA drive capability at TTL levels Ideal for oscillator replacement Advanced, low power CMOS process Block Diagram VDD GND 2 S1, S0 PLL Clock Synthesis and Control Circuitry Crystal Oscillator X2 Output Buffer CLK1 14.31818MHz crystal X1 or clock Output Buffer CLK2 1 Revision 120799 Printed 11/15/00 Integrated Circuit Systems, Inc. 525 Race Street San Jose CA95126 (408)295-9800tel www.icst.com MDS 1449B C MK1449B Sound/SCSI+Fast Ethernet Clock Pin Assignment X1/ICLK VDD GND CLK2 1 2 3 4 8 7 6 5 X2 S1 S0 CLK1 Clock Decoding Table (MHz) S1 0 0 1 1 S0 0 1 0 1 CLK1 tes...