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參數(shù)資料
| 型號(hào)： | PI6C484321FBE |
| 廠商： | Pericom Semiconductor Corp. |
| 英文描述： | 260MHz Crystal-to-3.3V Differential LVPECL Frequency Synthesizer |
| 中文描述： | 260MHz水晶至3.3V的差分LVPECL頻率合成器 |
| 文件頁(yè)數(shù)： | 2/9頁(yè) |
| 文件大?。?/td> | 273K |
| 代理商： | PI6C484321FBE |
2
PS8765A 08/01/05
PI6C484321
260MHz Crystal-to-3.3V Differential
LVPECL Frequency Synthesizer
Functional Description
The following functional description describes operations using
a 25MHz crystal. Valid PLL loop divider values for different
crystal or input frequencies are defined in the Input Frequency
Characteristics, Table 5, NOTE 1.
The PI6C484321 features a fully integrated PLL, thus requires
no external components for setting the loop bandwidth. A funda-
mental crystal is the input to the internal oscillator. The output
of the oscillator is fed into the phase detector. A 25MHz crystal
provides a 25MHz reference frequency to the phase detector. The
actual VCO range of the PLL is 320MHz to 1.1GHz. The output
of the M divider is used by the phase detector.
The phase detector and the M divider force the VCO output
frequency to be M times the reference frequency by adjusting
the VCO control voltage. Note that for some illegal values of M
(either too high or too low), the PLL will not achieve lock. The
output of the VCO is scaled by a divider prior to being sent to
each of the LVPECL output buffers. The divider provides a 50%
output duty cycle.
The programmable feature that selects the M divider and N out-
put divider supports two modes: parallel and serial modes. Figure
1 shows the timing diagram for each mode. In parallel mode, the
nP_LOAD input is initially LOW. The data on inputs M0 through
M8 and N0 and N1 is passed directly to the M divider and N out-
put divider. On the LOW-to-HIGH transition of the nP_LOAD
input, the data is latched and the M divider remains loaded until
the next LOW transition on nP_LOAD or until a serial event oc-
curs. As a result, the M and N bits can be hardwired to set the
M divider and N output divider to a specific default state that
will automatically occur during power-up. The TEST output is
LOW when operating in the parallel input mode. The relation-
ship between the VCO frequency, the crystal frequency and the
T1
0
0
1
1
T0
0
1
0
1
TEST Output
LOW
S_Data
Output of M divider
CMOS Fout
Parallel & Serial Load Operations
M divider is defined as follows:
fVCO = fxtal x M
The M value and the required values of M0 through M8 are
shown in Table 3B to program the VCO Frequency Function
Table. The output frequency is defined as follows:
Serial operation occurs when nP_LOAD is HIGH and S_LOAD
is LOW. The shift register is loaded by sampling the S_DATA
bits with the rising edge of S_CLOCK. The contents of the shift
register are loaded into the M divider and N output divider when
S_LOAD transitions from LOW-to-HIGH. The M divide and N
output divide values are latched on the HIGH-to-LOW transition
of S_LOAD. If S_LOAD is held HIGH, data at the S_DATA in-
put is passed directly to the M divider and N output divider on
each rising edge of S_CLOCK. The serial mode can be used to
program the M and N bits and test bits T1 and T0. The internal
registers T0 and T1 determine the state of the TEST output as
follows:
fOUT = fVCO = fxtal x M
N N
Time
S
ERIAL
L
OADING
P
ARALLEL
L
OADING
M, N
t
S
t
H
t
S
t
H
t
S
T 1
T0
*
NULL
N1
N0
M8
M7
M6
M5
M4
M3
M2
M1
M0
S_CLOCK
S_DATA
S_LOAD
nP_LOAD
M0:M8, N0:N1
nP_LOAD
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PI6C4853111 | 制造商:PERICOM 制造商全稱:Pericom Semiconductor Corporation 功能描述:2.5V/3.3V 500MHz Low Skew 1-to-10 Differential to LVPECL Fanout Buffer with 2 to 1 Differential Clock Input Mux |
| PI6C4853111FAE | 功能描述:時(shí)鐘緩沖器 0.25um1P4M 2.5/3.3V Salicid RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:5 最大輸入頻率:40 MHz 傳播延遲（最大值）: 電源電壓-最大:3.45 V 電源電壓-最小:2.375 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:LLP-24 封裝:Reel |
| PI6C4853111FAEX | 功能描述:時(shí)鐘緩沖器 0.25um1P4M 2.5/3.3V Salicid RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:5 最大輸入頻率:40 MHz 傳播延遲（最大值）: 電源電壓-最大:3.45 V 電源電壓-最小:2.375 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:LLP-24 封裝:Reel |
| PI6C485311WE | 功能描述:時(shí)鐘緩沖器 3.3V Low Skew 1:2 Diff RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:5 最大輸入頻率:40 MHz 傳播延遲（最大值）: 電源電壓-最大:3.45 V 電源電壓-最小:2.375 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:LLP-24 封裝:Reel |
| PI6C485311WEX | 功能描述:時(shí)鐘緩沖器 3.3V Low Skew 1:2 Diff RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:5 最大輸入頻率:40 MHz 傳播延遲（最大值）: 電源電壓-最大:3.45 V 電源電壓-最小:2.375 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:LLP-24 封裝:Reel |
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