MPC950

Manufacturer Part NumberMPC950
ManufacturerFreescale Semiconductor, Inc
MPC950 datasheet
 


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MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
Low Voltage PLL Clock Driver
The MPC950/951 are 3.3V compatible, PLL based clock driver
devices targeted for high performance clock tree designs. With output
frequencies of up to 180MHz and output skews of 375ps the MPC950 is
ideal for the most demanding clock tree designs. The devices employ a
fully differential PLL design to minimize cycle–to–cycle and long term
jitter. This parameter is of significant importance when the clock driver is
providing the reference clock for PLL’s on board today’s microprocessors
and ASiC’s. The devices offer 9 low skew outputs, the outputs are
configurable to support the clocking needs of the various high
performance microprocessors.
Fully Integrated PLL
Oscillator or Crystal Reference Input
Output Frequency up to 180MHz
Outputs Disable in High Impedance
Compatible with PowerPC , Intel and High Performance RISC
Microprocessors
TQFP Packaging
Output Frequency Configurable
100ps Typical Cycle–to–Cycle Jitter
Two selectable feedback division ratios are available on the MPC950
to provide input reference clock flexibility. The FBSEL pin will choose
between a divide by 8 or a divide by 16 of the VCO frequency to be
compared with the input reference to the MPC950. The internal VCO is
running at either 2x or 4x the high speed output, depending on
configuration, so that the input reference will be either one half, one fourth
or one eighth the high speed output.
The MPC951 replaces the crystal oscillator and internal feedback of the MPC950 with a differential PECL reference input and
an external feedback input. These features allow for the MPC951 to be used as a zero delay, low skew fanout buffer. In addition,
the external feedback allows for a wider variety of input–to–output frequency relationships. The MPC951 REF_SEL pin allows for
the selection of an alternate LVCMOS input clock to be used as a test clock or to provide the reference for the PLL from an
LVCMOS source.
The MPC950 provides an external test clock input for scan clock distribution or system diagnostics. In addition the REF_SEL
pin allows the user to select between a crystal input to an on–board oscillator for the reference or to chose a TTL level oscillator
input directly. The on–board crystal oscillator requires no external components beyond a series resonant crystal.
Both the MPC950 and MPC951 are fully 3.3V compatible and require no external loop filter components. All inputs accept
LVCMOS or LVTTL compatible levels while the outputs provide LVCMOS levels with the capability to drive terminated 50Ω
transmission lines. Select inputs do not have internal pull–up/pull–down resistors and thus must be set externally. If the
PECL_CLK inputs are not used, they can be left open. For series terminated 50Ω lines, each of the MPC950/951 outputs can
drive two traces giving the device an effective fanout of 1:18. The device is packaged in a 7x7mm 32–lead TQFP package to
provide the optimum combination of board density and performance.
PowerPC is a trademark of International Business Machines Corporation. Pentium is a trademark of Intel Corporation.
2/97
Motorola, Inc. 1997
1
REV 4
MPC950
MPC951
LOW VOLTAGE
PLL CLOCK DRIVER
FA SUFFIX
32–LEAD TQFP PACKAGE
CASE 873A–02

MPC950 Summary of contents