ASM2I9942C

May 2005 ASM2I9942C rev 0.2 Low Voltage 1:18 Clock Distribution Chip Features ƒ LVCMOS/LVTTL Clock Input ƒ 2.5V LVCMOS Outputs for Pentium IITM* Microprocessor Support ƒ 150pS Maximum Targeted Output–to–Output Skew ƒ Maximum Output Frequency of 250MHz @ 3.3 VCC ƒ 32–Lead TQFP and LQFP Packaging ƒ Single 3.3V or 2.5V Supply. ƒ Pin and Function compatible to MPC942C. Functional Description The ASM2I9942C is a 1:18 low voltage clock distribution chip with 2.5V or 3.3V LVCMOS output capabilities. The device is offered in two versions; the ASM2I9942C has an LVCMOS input clock while the ASM2I9942P has an LVPECL input clock. The 18 outputs are 2.5V or 3.3V LVCMOS compatible and feature the drive strength to drive 50Ω series or parallel terminated transmission lines. With output–to–output skews of 200pS, the ASM2I9942C is ideal as a clock distribution chip for the most demanding of synchronous systems. The 2.5V outputs also make the device ideal for supplying clocks for a high performance Pentium II TM microprocessor based design. With a low output impedance (≈12Ω), in both the HIGH and LOW logic states, the output buffers of the ASM2I9942C are ideal for driving series terminated transmission lines. With an output impedance of 12Ω, the ASM2I9942C can drive two series terminated transmission lines from each output. This capability gives the ASM2I9942C an effective fanout of 1:36. The ASM2I9942C provides enough copies of low skew clocks for most high performance synchronous system...