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参数资料
| 型号： | MPC9330ACR2 |
| 厂商： | FREESCALE SEMICONDUCTOR INC |
| 元件分类： | 时钟产生/分配 |
| 英文描述： | 120 MHz, OTHER CLOCK GENERATOR, PQFP32 |
| 封装： | LEAD FREE, LQFP-32 |
| 文件页数： | 11/12页 |
| 文件大小： | 312K |
| 代理商： | MPC9330ACR2 |
Advanced Clock Drivers Devices
8
Freescale Semiconductor
MPC9330
APPLICATIONS INFORMATION
Power Supply Filtering
The MPC9330 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 MPC9330 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 MPC9330 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 5 mA (10 mA maximum), assuming that a
minimum of 2.985 V must be maintained on the VCC_PLL pin.
of 10–15
to meet the voltage drop criteria.
Figure 3. 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 3, the filter cut-off frequency is around
3-5 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 MPC9330 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.
Driving Transmission Lines
The MPC9330 clock driver was designed to drive high-
speed signals in a terminated transmission line environment.
To provide the optimum flexibility to the user, the output
drivers were designed to exhibit the lowest impedance
possible. With an output impedance of less than 20
, the
drivers can drive either parallel or series terminated
transmission lines. For more information on transmission
lines, the reader is referred to Freescale application note
AN1091. In most high performance clock networks,
point-to-point distribution of signals is the method of choice.
In a point-to-point scheme, either series terminated or parallel
terminated transmission lines can be used. The parallel
technique terminates the signal at the end of the line with a
50
resistance to VCC÷ 2.
This technique draws a fairly high level of DC current and
thus only a single terminated line can be driven by each
output of the MPC9330 clock driver. For the series terminated
case, however, there is no DC current draw, thus the outputs
can drive multiple series terminated lines. Figure 4 illustrates
an output driving a single series terminated line versus two
series terminated lines in parallel. When taken to its extreme,
the fanout of the MPC9330 clock driver is effectively doubled
due to its capability to drive multiple lines.
Figure 4. Single versus Dual Transmission Lines
The waveform plots in Figure 4 show the simulation
results of an output driving a single line versus two lines. In
both cases, the drive capability of the MPC9330 output buffer
is more than sufficient to drive 50
transmission lines on the
incident edge. Note from the delay measurements in the
simulations, a delta of only 43 ps exists between the two
differently loaded outputs. This suggests that the dual line
driving need not be used exclusively to maintain the tight
output-to-output skew of the MPC9330. The output waveform
in Figure 5 shows a step in the waveform; this step is caused
by the impedance mismatch seen looking into the driver. The
parallel combination of the 36
series resistor plus the
output impedance does not match the parallel combination of
VCC_PLL
VCC
MPC9330
10 nF
RF = 10 – 15
CF
33...100 nF
RF
VCC
CF = 22 F
14
IN
MPC9330
OUTPUT
BUFFER
RS = 36
ZO = 50
OutA
14
IN
MPC9330
OUTPUT
BUFFER
RS = 36
ZO = 50
OutB0
RS = 36
ZO = 50
OutB1
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MPC9330FA | 功能描述:时钟发生器及支持产品 3.3V 200MHz Clock Generator RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
| MPC9330FAR2 | 制造商:Integrated Device Technology Inc 功能描述:MPC9330FAR2 - Tape and Reel |
| MPC9331 | 制造商:MOTOROLA 制造商全称:Motorola, Inc 功能描述:3.3 V 1:6 LVCMOS PLL Clock Generator |
| MPC9331AC | 功能描述:时钟发生器及支持产品 FSL1-6 LVCMOS/LVPECL LVCMOS PLL Clk Gen RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
| MPC9331ACR2 | 功能描述:时钟发生器及支持产品 FSL1-6 LVCMOS/LVPECL LVCMOS PLL Clk Gen RoHS:否 制造商:Silicon Labs 类型:Clock Generators 最大输入频率:14.318 MHz 最大输出频率:166 MHz 输出端数量:16 占空比 - 最大:55 % 工作电源电压:3.3 V 工作电源电流:1 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-56 |
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