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參數(shù)資料
| 型號： | SY89842U |
| 廠商： | Micrel Semiconductor,Inc. |
| 英文描述： | Precision CML Runt Pulse Eliminator 2:1 Multiplexer |
| 中文描述： | 精密白血病短脈沖消除2:1多路復(fù)用器 |
| 文件頁數(shù)： | 8/16頁 |
| 文件大?。?/td> | 668K |
| 代理商： | SY89842U |
Micrel, Inc.
SY89842U
March 2005
M9999-030805
hbwhelp@micrel.com
or (408) 955-1690
8
Functional Description
RPE MUX and Fail-Safe Input
The SY89842U is optimized for clock switchover
applications where switching from one clock to
another clock without runt pulses (short cycles) is
required. It features two unique circuits:
Runt-Pulse Eliminator (RPE) Circuit
The RPE MUX provides a “glitchless” switchover
between two clocks and prevents any runt pulses
from occurring during the switchover transition. The
design of both clock inputs is identical (i.e., the
switchover sequence and protection is symmetrical
for both input pair, IN0 or IN1. Thus, either input pair
may be defined as the primary input). If not required,
the RPE function can be permanently disabled to
allow the switchover between inputs to occur
immediately. If the CAP pin is tied directly to V
CC
, the
RPE function will be disabled and the multiplexer will
function as a normal multiplexer.
Fail-Safe Input (FSI) Circuit
The FSI function provides protection against a
selected input pair that drops below the minimum
amplitude requirement. If the selected input pair
drops sufficiently below the 100mV minimum single-
ended input amplitude limit (V
IN
), or 200mV
differentially (V
DIFF_IN
), the output will latch to the last
valid clock state.
RPE and FSI Functionality
The basic operation of the RPE MUX and FSI
functionality is described with the following four case
descriptions. All descriptions are related to the true
inputs and outputs. The primary (or selected) clock
is called CLK1; the secondary (or alternate) clock is
called CLK2. Due to the totally asynchronous
relation of the IN and SEL signals and an additional
internal protection against metastability, the number
of pulses required for the operations described in
cases 1-4 can vary within certain limits. Refer to
“Timing Diagrams” section for detailed information.
Case #1: Two Normal Clocks and RPE Enabled
In this case, the frequency difference between the
two running clocks, IN0 and IN1, must not be greater
than 1.5:1. For example, if the IN0 clock is 500MHz,
the IN1 clock must be within the range of 334MHz to
750MHz.
If the SEL input changes state to select the alternate
clock, the switchover from CLK1 to CLK2 will occur
in three stages.
Stage 1: The output will continue to follow CLK1
for a limited number of pulses.
Stage 2: The output will remain LOW for a
limited number of pulses of CLK2.
Stage 3: The output follows CLK2.
Timing Diagram 1
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SY89845U | PRECISION CML RUNT PULSE ELIMINATOR 2:1 MUX WITH 1:2 FANOUT AND INTERNAL TERMINATION |
| SY89845UMG | PRECISION CML RUNT PULSE ELIMINATOR 2:1 MUX WITH 1:2 FANOUT AND INTERNAL TERMINATION |
| SY89845UMGTR | PRECISION CML RUNT PULSE ELIMINATOR 2:1 MUX WITH 1:2 FANOUT AND INTERNAL TERMINATION |
| SY89858UMG | PRECISION LOW POWER 1:8 LVPECL FANOUT BUFFER WITH INTERNAL TERMINATION |
| SY89858UMGTR | PRECISION LOW POWER 1:8 LVPECL FANOUT BUFFER WITH INTERNAL TERMINATION |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SY89842U_10 | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:Precision CML Runt Pulse Eliminator 2:1 |
| SY89842UMG | 功能描述:編碼器、解碼器、復(fù)用器和解復(fù)用器 Precision 2:1 CML MUX w/ RPE & FSI (I Temp, Green) RoHS:否 制造商:Micrel 產(chǎn)品:Multiplexers 邏輯系列:CMOS 位數(shù): 線路數(shù)量（輸入/輸出）:2 / 12 傳播延遲時間:350 ps, 400 ps 電源電壓-最大:2.625 V, 3.6 V 電源電壓-最小:2.375 V, 3 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Tray |
| SY89842UMG TR | 功能描述:編碼器、解碼器、復(fù)用器和解復(fù)用器 Precision 2:1 CML MUX w/ RPE & FSI (I Temp, Green) RoHS:否 制造商:Micrel 產(chǎn)品:Multiplexers 邏輯系列:CMOS 位數(shù): 線路數(shù)量（輸入/輸出）:2 / 12 傳播延遲時間:350 ps, 400 ps 電源電壓-最大:2.625 V, 3.6 V 電源電壓-最小:2.375 V, 3 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Tray |
| SY89842UMGTR | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:Precision CML Runt Pulse Eliminator 2:1 |
| SY89843U | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:Precision LVPECL Runt Pulse Eliminator 2:1 |
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