MC12439FN Motorola, MC12439FN Datasheet

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MC12439FN

Manufacturer Part Number
MC12439FN
Description
HIGH FREQUENCY PLL CLOCK GENERATOR
Manufacturer
Motorola
Datasheet

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MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
High Frequency Clock Generator
applications that require both serial and parallel interfaces. Its internal
VCO will operate over a range of frequencies from 400 to 800MHz. The
differential PECL output can be configured to be the VCO frequency
divided by 1, 2, 4, or 8. With the output configured to divide the VCO
frequency by 1, and with a 16.66MHz external quartz crystal used to
provide the reference frequency, the output frequency can be specified in
16.66MHz steps.
Functional Description
oscillator is sent directly to the phase detector. With a 16.66MHz crystal, this provides a reference frequency of 16.66MHz.
Although this data sheet illustrates functionality only for a 16MHz and 16.66MHz crystal, any crystal in the 10–20MHz range can
be used. In addition to the crystal, an LVCMOS input can also be used as the PLL reference. The reference is selected via the
XTAL_SEL input pin.
the serial or parallel interfaces. The output of this loop divider is also applied to the phase detector.
adjusting the VCO control voltage. Note that for some values of M (either too high or too low) the PLL will not achieve loop lock.
is configured through either the serial or the parallel interfaces, and can provide one of four division ratios (1, 2, 4, or 8). This
divider extends performance of the part while providing a 50% duty cycle.
in 50
inputs to configure the internal counters. Normally, on system reset, the P_LOAD input is held LOW until sometime after power
becomes valid. On the LOW–to–HIGH transition of P_LOAD, the parallel inputs are captured. The parallel interface has priority
over the serial interface. Internal pullup resistors are provided on the M[6:0] and N[1:0] inputs to reduce component count in the
application of the chip.
The serial input S_DATA must meet setup and hold timing as specified in the AC Characteristics section of this document. The
configuration latches will capture the value of the shift register on the HIGH–to–LOW edge of the S_LOAD input. See the
programming section for more information.
programming section for more information.
PLL reference clock, thereby causing the frequency reduction to happen relatively slowly. Upon de–assertion of the
PWR_DOWN pin, the FOUT input will step back up to its programmed frequency in four discrete increments.
1/97
Motorola, Inc. 1997
50 to 800MHz Differential PECL Outputs
Minimal Frequency Over–Shoot
Synthesized Architecture
Serial 3–Wire Interface
Parallel Interface for Power–Up
Quartz Crystal Interface
28–Lead PLCC Package
Operates from 3.3V or 5.0V Power Supply
The MC12439 is a general purpose synthesized clock source targeting
The internal oscillator uses the external quartz crystal as the basis of its frequency reference. The output of the reference
The VCO within the PLL operates over a range of 400 to 800MHz. Its output is scaled by a divider that is configured by either
The phase detector and loop filter attempt to force the VCO output frequency to be M times the reference frequency by
The output of the VCO is also passed through an output divider before being sent to the PECL output driver. This output divider
The output driver is driven differentially from the output divider, and is capable of driving a pair of transmission lines terminated
The configuration logic has two sections: serial and parallel. The parallel interface uses the values at the M[6:0] and N[1:0]
The serial interface centers on a twelve bit shift register. The shift register shifts once per rising edge of the S_CLOCK input.
The TEST output reflects various internal node values, and is controlled by the T[2:0] bits in the serial data stream. See the
The PWR_DOWN pin, when asserted, will synchronously divide the FOUT by 16. The power down sequence is clocked by the
25ps Typical Peak–to–Peak Output Jitter
to V CC – 2.0.
1
REV 3
HIGH FREQUENCY PLL
CLOCK GENERATOR
28–LEAD PLCC PACKAGE
MC12439
CASE 776–02
FN SUFFIX

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MC12439FN Summary of contents

Page 1

... The PWR_DOWN pin, when asserted, will synchronously divide the FOUT by 16. The power down sequence is clocked by the PLL reference clock, thereby causing the frequency reduction to happen relatively slowly. Upon de–assertion of the PWR_DOWN pin, the FOUT input will step back up to its programmed frequency in four discrete increments. 1/97 Motorola, Inc. 1997 1 REV 3 MC12439 ...

Page 2

... LVCMOS input that forces the FOUT output to synchronously reduce its frequency by a factor of 16. FREF_EXT Int. Pulldown LVCMOS input which can be used as the PLL reference frequency. XTAL_SEL Int. Pullup LVCMOS input that selects between the XTAL and FREF_EXT PLL reference inputs. A HIGH selects the XTAL input. MOTOROLA V CC TEST GND ...

Page 3

... For computer applications another useful frequency base would be 16.666MHz. From this reference one can generate a family of output frequencies at multiples of the 33.333MHz PCI clock example to generate a 533.333MHz clock 3 MC12439 +3.3 or 5.0V PLL_V CC +3.3 or 5.0V V CC0 25 24 FOUT 23 FOUT 20 TEST LATCH 3–BIT SR 22 48, so M[8:0] = 0110000. MOTOROLA ...

Page 4

... S_LOAD M[6: N[1:0] P_LOAD MOTOROLA configuration stream not configurable through the parallel interface. Although it is possible to select the node that represents FOUT, the CMOS output may not be able to toggle fast enough for some of the higher output frequencies. The T2, T1 and T0 control bits are preset to ‘000’ when P_LOAD is LOW so that the PECL FOUT outputs are as jitter– ...

Page 5

... MC12439 FOUT N DIVIDE ( (VIA ENABLE GATE) 7 TEST TEST MUX 0 Max Unit Condition 3.3 to 5.0V 0 3.3 to 5.0V 1 Continuous Current –0.8mA, (Note 2.) 0 0.8mA, (Note 2.) 2. 3.3V (Notes 3., 4.) 1. 3.3V (Notes 3., 4.) 110 mA 20 MOTOROLA ...

Page 6

... Maximum frequency on FREF_EXT is a function of the internal M counter limitations. The phase detector can handle up to 100MHz on the input, but the M counter must remain in the valid range See Applications Information section for additional information – 2.0V pulldown. MOTOROLA Min Max S_CLOCK ...

Page 7

... The parallel capacitor combination shown ensures that a low impedance path to ground exists Value for frequencies well above the bandwidth of the PLL. PLL_VCC MC12439 VCC Figure 5. Power Supply Filter 7 MC12439 to meet the voltage drop criteria. The 3. =10– 0.01 F 0.01 F MOTOROLA ...

Page 8

... Special attention should be paid to the layout of the crystal to MOTOROLA ensure a stable, jitter free interface between the crystal and the on–board oscillator. Although the MC12439 has several design features to ...

Page 9

... ECL devices. Note that if a larger swing is desired the 12439 could drive a single gate ECLinPS Lite amplifier like the MC100LVEL16. The LVEL16 will speed up the output edge rates and produce a full swing ECL output at 800MHz. 9 MC12439 Spec Limit N=1 600 700 800 MOTOROLA ...

Page 10

... PROTRUSION OR INTRUSION. THE DAMBAR PROTRUSION(S) SHALL NOT CAUSE THE H DIMENSION TO BE GREATER THAN 0.037 (0.940). THE DAMBAR INTRUSION(S) SHALL NOT CAUSE THE H DIMENSION TO BE SMALLER THAN 0.025 (0.635). MOTOROLA OUTLINE DIMENSIONS FN SUFFIX PLASTIC PLCC PACKAGE CASE 776–02 ISSUE D 0.007 (0.180) ...

Page 11

... Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “ ...

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