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参数资料
| 型号： | FD7745T-FREQ-T250 |
| 厂商： | PLETRONICS INC |
| 元件分类： | XO, clock |
| 英文描述： | CRYSTAL OSCILLATOR, CLOCK, 12 MHz - 32 MHz, LVCMOS OUTPUT |
| 封装： | ROHS COMPLIANT, CERAMIC, LCC-14 |
| 文件页数： | 6/12页 |
| 文件大小： | 185K |
| 代理商： | FD7745T-FREQ-T250 |
FD77T Series Multi-Output
CMOS Clock Oscillator
February 2008
www.pletronics.com
425-776-1880
3
Three programmable control inputs, S0, S1 and S2, may be used to control various aspects of FD77T
operation including selection of alternative frequency set(s), selection of SSC functionality, output tri-state
and power-down.
Reference Oscillator
The Reference Oscillator is an AT cut quartz crystal based oscillator. This oscillator is very similar to the
Pletronics SM77xxH product oscillator. This signal is the lowest jitter and can be an output on Out1, Out2
or Out3 and can be divided down by the Divider #1. The user may specify any frequency between 12MHz
and 32MHz for this reference. All output frequencies are derived from (referenced to) this Reference
Oscillator.
Reference Oscillator - VCXO
The reference oscillator frequency can be modulated by the Vcontrol input, if the VCXO option is selected.
As this Reference Signal is the reference for all other parts of this circuit, all PLLs will be modulated also.
PLL Multipliers
There are 4 each independent PLL Multipliers and these can multiply the Reference Oscillator frequency
from 1 (bypass mode) to any value that is <=230MHz (the lowest frequency is the Reference Oscillator
frequency).
Each of the PLL Multipliers can have two setup options, 0 or 1, depending on which option is chosen and
set by the Sx control signals and the user’s definitions are stored in eePROM.
Spread Spectrum
Each PLL has its individual Spread Spectrum (SS) function that can be enabled. This permits the
modulation of the output frequency by a user-set amount. The modulation can be centered on the output
frequency or down side only. Which of the 1 of 8 SS settings is being used is set by the Sx input and the
user definition. The value is a percentage of the output frequency that will be modulated.
SS Option
Down Side Modulation
Centered Modulation
0
No SS
1
-0.25%
+
_0.25%
2
-0.50%
+
_0.50%
3
-0.75%
+
_0.75%
4
-1.00%
+
_1.00%
5
-1.25%
+
_1.25%
6
-1.50%
+
_1.50%
7
-2.00%
+
_2.00%
Divider Section
The dividers operate on the output of the PLLs. There are two dividers on each PLL that divide by 1
through 127, the value is user defined. There is only 1 setting allowed per divider. These are not set by the
Sx input state.
The dividers add very little jitter to the output signals.
Multiplexers
MUX #1 selects the input to the Divider #1, this can be the reference oscillator signal or the output from
PLL Multiplier #1. MUX #2 through MUX #7 connect various divider outputs to the output buffers.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| FD7745TL-25.0M-PLE | 制造商:PLETRONICS 制造商全称:Pletronics, Inc. 功能描述:Multi-Output CMOS Clock Oscillator |
| FD7745TL-25.0M-PLE-1K | 制造商:PLETRONICS 制造商全称:Pletronics, Inc. 功能描述:Multi-Output CMOS Clock Oscillator |
| FD7745TL-25.0M-PLE-T250 | 制造商:PLETRONICS 制造商全称:Pletronics, Inc. 功能描述:Multi-Output CMOS Clock Oscillator |
| FD7745TL-25.0M-PLE-T500 | 制造商:PLETRONICS 制造商全称:Pletronics, Inc. 功能描述:Multi-Output CMOS Clock Oscillator |
| FD7745TLE-25.0M-PLE | 制造商:PLETRONICS 制造商全称:Pletronics, Inc. 功能描述:Multi-Output CMOS Clock Oscillator |
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