MPC952

* Absolute maximum continuous ratings are those values beyond which damage to the device may occur. Exposure to these conditions or conditions beyond those indicated may adversely affect device reliability. Functional operation under absolute-maximum-rated conditions is not implied.

The MPC952 is a 3.3V compatible, PLL based clock driver device targeted for high performance clock tree applications. The device features a fully integrated PLL with no external components required.

With output frequencies of up to 180MHz and eleven low skew outputs the MPC952 is well suited for high performance designs. The MPC952 employs a fully differential PLL design to optimize jitter and noise rejection performance. Jitter is an increasingly important parameter as more microprocessors and ASiC's are employing on chip PLL clock distribution.
• Fully Integrated PLL
• Output Frequency up to 180MHz
• High Impedance Disabled Outputs
• Compatible with PowerPCE, Intel and High Performance RISC Microprocessors
• Output Frequency Configurable
• LQFP Packaging
• ±100ps CycletoCycle Jitter
The MPC952 features three banks of individually configurable outputs.

The banks MPC952 contain 5 outputs, 4 outputs and 2 outputs. The internal divide circuitry allows for output frequency ratios of 1:1, 2:1, 3:1 and 3:2:1. The output frequency relationship is controlled by the fsel frequency control pins. The fsel pins as well as the other inputs are LVCMOS/LVTTL compatible inputs.

The MPC952 uses external feedback to the PLL. This features allows for the use of the device as a "zero delay" buffer. Any of the eleven outputs can be used as the feedback to the PLL. The VCO_Sel pin allows for the choice of two VCO ranges to optimize PLL stability and jitter performance. The MR/OE pin MPC952 allows the user to force the outputs into high impedance for board level test.

For system debug the PLL of the MPC952 can be bypassed. When forced to a logic HIGH, the PLLEN input will route the signal on the RefClk input around the PLL directly to the internal dividers. Because the signal is routed through the dividers, it may take several transitions of the RefClk to affect a transition on the outputs. MPC952 features allows a designer to single step the design for debug purposes.

The outputs of the MPC952 are LVCMOS outputs. The outputs are optimally designed to drive terminated transmission lines.

For applications using series terminated transmission lines each MPC952 output can drive two lines. This capability provides an effective fanout of 22, more than enough clocks for most clock tree designs. For more information about MPC952 on driving transmission lines consult the applications section of this data sheet.