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參數(shù)資料
| 型號： | MPC9773AER2 |
| 廠商： | FREESCALE SEMICONDUCTOR INC |
| 元件分類： | 時鐘及定時 |
| 英文描述： | 9773 SERIES, PLL BASED CLOCK DRIVER, 13 TRUE OUTPUT(S), 0 INVERTED OUTPUT(S), PQFP52 |
| 封裝： | 10 X 10 MM, 1.40 MM HEIGHT, 0.65 MM PITCH, LEAD FREE, PLASTIC, LQFP-52 |
| 文件頁數(shù)： | 3/19頁 |
| 文件大?。?/td> | 491K |
| 代理商： | MPC9773AER2 |
Advanced Clock Drivers Device Data
Freescale Semiconductor
11
MPC9773
Power Supply Filtering
The MPC9773 is a mixed analog/digital product. Its analog
circuitry is naturally susceptible to random noise, especially if
this noise is seen on the power supply pins. Random noise
on the VCC_PLL power supply impacts the device
characteristics, for instance I/O jitter. The MPC9773 provides
separate power supplies for the output buffers (VCC) and the
phase-locked loop (VCC_PLL) of the device. The purpose of
this design technique is to isolate the high switching noise
digital outputs from the relatively sensitive internal analog
phase-locked loop. In a digital system environment where it
is more difficult to minimize noise on the power supplies, a
second level of isolation may be required. The simple but
effective form of isolation is a power supply filter on the
power supply filter scheme. The MPC9773 frequency and
phase stability is most susceptible to noise with spectral
content in the 100-kHz to 20-MHz range. Therefore, the filter
should be designed to target this range. The key parameter
that needs to be met in the final filter design is the DC voltage
drop across the series filter resistor RF. From the data sheet
the ICC_PLL current (the current sourced through the VCC_PLL
pin) is typically 8 mA (13.5 mA maximum), assuming that a
minimum of 3.0 V must be maintained on the VCC_PLL pin.
5–10
to meet the voltage drop criteria.
Figure 7. VCC_PLL Power Supply Filter
The minimum values for RF and the filter capacitor CF are
defined by the required filter characteristics: the RC filter
should provide an attenuation greater than 40 dB for noise
whose spectral content is above 100 kHz. In the example RC
filter shown in Figure 7, the filter cut-off frequency is around
4.5 kHz and the noise attenuation at 100 kHz is better than
42 dB.
As the noise frequency crosses the series resonant point
of an individual capacitor, its overall impedance begins to
look inductive and thus increases with increasing frequency.
The parallel capacitor combination shown ensures that a low
impedance path to ground exists for frequencies well above
the bandwidth of the PLL. Although the MPC9773 has
several design features to minimize the susceptibility to
power supply noise (isolated power and grounds and fully
differential PLL), there still may be applications in which
overall performance is being degraded due to system power
supply noise. The power supply filter schemes discussed in
this section should be adequate to eliminate power supply
noise related problems in most designs.
Using the MPC9773 in Zero-Delay Applications
Nested clock trees are typical applications for the
MPC9773. Designs using the MPC9773 as an LVCMOS PLL
fanout buffer with zero insertion delay will show significantly
lower clock skew than clock distributions developed from
CMOS fanout buffers. The external feedback option of the
MPC9773 clock driver allows for its use as a zero delay
buffer. The PLL aligns the feedback clock output edge with
the clock input reference edge, resulting in a near zero delay
through the device (the propagation delay through the device
is virtually eliminated). The maximum insertion delay of the
device in zero-delay applications is measured between the
reference clock input and any output. This effective delay
consists of the static phase offset, I/O jitter (phase or long-
term jitter), feedback path delay and the output-to-output
skew error relative to the feedback output.
Calculation of Part-to-Part Skew
The MPC9773 zero delay buffer supports applications
where critical clock signal timing can be maintained across
several devices. If the reference clock inputs of two or more
MPC9773 are connected together, the maximum overall
timing uncertainty from the common CCLKx input to any
output is:
tSK(PP) = t() + tSK(O) + tPD, LINE(FB) + tJIT() CF
This maximum timing uncertainty consists of 4
components: static phase offset, output skew, feedback
board trace delay, and I/O (phase) jitter:
Figure 8. MPC9773 Maximum Device-to-Device Skew
VCC_PLL
VCC
MPC9773
10 nF
RF = 5–10
CF
33...100 nF
RF
VCC
CF = 22 F
tPD,LINE(FB)
tJIT()
+tSK(O)
–t()
+t()
tJIT()
+tSK(O)
tSK(PP)
Max. skew
CCLKCommon
QFBDevice 1
Any QDevice 1
QFBDevice2
Any QDevice 2
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MPC9773FA | 功能描述:鎖相環(huán) - PLL 3.3V 240MHz Clock Generator RoHS:否 制造商:Silicon Labs 類型:PLL Clock Multiplier 電路數(shù)量:1 最大輸入頻率:710 MHz 最小輸入頻率:0.002 MHz 輸出頻率范圍:0.002 MHz to 808 MHz 電源電壓-最大:3.63 V 電源電壓-最小:1.71 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:QFN-36 封裝:Tray |
| MPC9773FAR2 | 制造商:Integrated Device Technology Inc 功能描述:PLL Clock Driver Single 52-Pin LQFP T/R 制造商:Integrated Device Technology Inc 功能描述:MPC9773FAR2 - Tape and Reel |
| MPC9774 | 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:3.3V / 2,5V 1:14 LVCMOS PLL CLOCK GENERATOR |
| MPC9774AE | 功能描述:時鐘發(fā)生器及支持產(chǎn)品 3.3V 125MHz Clock Generator RoHS:否 制造商:Silicon Labs 類型:Clock Generators 最大輸入頻率:14.318 MHz 最大輸出頻率:166 MHz 輸出端數(shù)量:16 占空比 - 最大:55 % 工作電源電壓:3.3 V 工作電源電流:1 mA 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:QFN-56 |
| MPC9774AER2 | 功能描述:IC PLL CLK GEN 1:14 3.3V 52-LQFP RoHS:是 類別:集成電路 (IC) >> 時鐘/計時 - 時鐘發(fā)生器，PLL，頻率合成器 系列:- 標準包裝:1,000 系列:- 類型:時鐘/頻率合成器，扇出分配 PLL:- 輸入:- 輸出:- 電路數(shù):- 比率 - 輸入:輸出:- 差分 - 輸入:輸出:- 頻率 - 最大:- 除法器/乘法器:- 電源電壓:- 工作溫度:- 安裝類型:表面貼裝 封裝/外殼:56-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:56-VFQFP-EP（8x8） 包裝:帶卷 (TR) 其它名稱:844S012AKI-01LFT |
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