MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

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REV 1

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Low Voltage PECL PLL Clock

Driver

The MPC992 is a 3.3V compatible, PLL based PECL clock generator

and distributor. The fully differential design ensures optimum skew and

PLL jitter performance. The performance of the device makes the

MPC992 ideal for workstations, main frame computer, telecommunication

and instrumentation applications. The device offers a crystal oscillator or

a differential PECL reference clock input to provide flexibility in the

reference clock interface. All of the control signals to the MPC992 are

LVTTL compatible inputs.

The MPC992 offers two banks of outputs which can be configured into

four different relationships. The output banks can be configured into 2:1,

3:1, 3:2 and 5:2 ratios to provide a wide variety of potential frequency

outputs. In addition to these two banks of outputs a synchronization output is also offered. The SYNC output will provide

information as to the time when the two output banks will transition positively in phase. This information can be important when

the odd ratios are used as it provides for a baseline point in the system timing. The SYNC output will pulse high for one Qa clock

period, centered on the rising Qa clock edge four edges prior to the Qb synchronous edge. The relationship is illustrated in the

timing diagrams in the data sheet.

The MPC992 offers several features to aid in system debug and test. The PECL reference input pins can be interfaced to a test

signal and the PLL can be bypassed to allow the designer to drive the MPC992 outputs directly. This allows for single stepping in

a system functional debug mode. In addition an overriding reset is provided which will force all of the Q outputs LOW upon

assertion.

The MPC992 is packaged in a 32–lead TQFP package to optimize both performance and board density.

Qan

Qan

(x4)

Qbn

Qbn

(x3)

SYNC

SYNC

(x1)

Frequency

Generator

PLL_EN

PECL_CLK

PECL_CLK

XTAL_SEL

XTAL

OSC

XTAL1

XTAL2

VCO_SEL

Integrated

PLL

x2

FSEL0

FSEL1

POR

Reset

MPC992 LOGIC DIAGRAM

1

0

0

1

0

1

MPC992

LOW VOLTAGE

PLL CLOCK DRIVER

FA SUFFIX

PLASTIC TQFP PACKAGE

CASE 873A-02