MPC9239 Datasheet, PDF (1/14 Pages) Freescale Semiconductor, Inc – 900 MHz Low Voltage LVPECL Clock Synthesizer

Freescale Semiconductor
Technical Data
MPC9239
Rev. 3, 08/2005
900 MHz Low Voltage LVPECL
Clock Synthesizer
MPC9239
The MPC9239 is a 3.3 V compatible, PLL based clock synthesizer targeted for
high performance clock generation in mid-range to high-performance telecom,
networking, and computing applications. With output frequencies from
3.125 MHz to 900 MHz and the support of differential LVPECL output signals the
device meets the needs of the most demanding clock applications.
900 MHz LOW VOLTAGE
CLOCK SYNTHESIZER
Features
• 3.125 MHz to 900 MHz synthesized clock output signal
• Differential LVPECL output
• LVCMOS compatible control inputs
• On-chip crystal oscillator for reference frequency generation
• Alternative LVCMOS compatible reference input
• 3.3 V power supply
• Fully integrated PLL
• Minimal frequency overshoot
• Serial 3-wire programming interface
• Parallel programming interface for power-up
• 28 PLCC and 32 LQFP packaging
• 28-lead and 32-lead Pb-free package available
• SiGe Technology
• Ambient temperature range 0°C to + 70°C
• Pin and function compatible to the MC12439
Functional Description
FN SUFFIX
28-LEAD PLCC PACKAGE
CASE 776-02
EI SUFFIX
28-LEAD PLCC PACKAGE
Pb-FREE PACKAGE
CASE 776-02
FA SUFFIX
32-LEAD LQFP PACKAGE
CASE 873A-04
AC SUFFIX
32-LEAD LQFP PACKAGE
Pb-FREE PACKAGE
CASE 873A-04
The internal crystal oscillator uses the external quartz crystal as the basis of
its frequency reference. The frequency of the internal crystal oscillator or external
reference clock signal is multiplied by the PLL. The VCO within the PLL operates over a range of 800 to 1800 MHz. Its output is
scaled by a divider that is configured by either the serial or parallel interfaces. The crystal oscillator frequency f_XTAL, the PLL
feedback-divider M and the PLL post-divider N determine the output frequency.
The feedback path of the PLL is internal. The PLL adjusts the VCO output frequency to be M times the reference frequency
by adjusting the VCO control voltage. Note that for some values of M (either too high or too low) the PLL will not achieve phase
lock. The PLL will be stable if the VCO frequency is within the specified VCO frequency range (800 to 1800 MHz). The M-value
must be programmed by the serial or parallel interface.
The PLL post-divider N 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. The output driver is driven
differentially from the output divider, and is capable of driving a pair of transmission lines terminated 50 Ω to V_CC – 2.0 V. The
positive supply voltage for the internal PLL is separated from the power supply for the core logic and output drivers to minimize
noise induced jitter.
The configuration logic has two sections: serial and parallel. The parallel interface uses the values at the M[6:0] and N[1:0]
inputs to configure the internal counters. It is recommended on system reset to hold the P_LOAD input LOW until 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 prevent the LVCMOS compatible control
inputs from floating. The serial interface centers on a twelve bit shift register. The shift register shifts once per rising edge of the
S_CLOCK input. 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.
Refer to the programming section for more information. The TEST output reflects various internal node values, and is controlled
by the T[2:0] bits in the serial data stream. In order to minimize the PLL jitter, it is recommended to avoid active signal on the
TEST output. The PWR_DOWN pin, when asserted, will synchronously divide the f_OUT 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 f_OUT input will step back up to its programmed frequency in four discrete increments.
© Freescale Semiconductor, Inc., 2005. All rights reserved.