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參數(shù)資料
| 型號： | DM9008 |
| 廠商： | Electronic Theatre Controls, Inc. |
| 英文描述： | ISA/Plug & Play Super Ethernet Contoller |
| 中文描述： | 的ISA /插頭 |
| 文件頁數(shù)： | 36/68頁 |
| 文件大?。?/td> | 403K |
| 代理商： | DM9008 |
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DM9008
ISA/Plug & Play Super Ethernet Contoller
be externally terminated with two 39 ohm resistors connected
in series if the standard 78 ohm transceiver drop cable is used.
In thin Ethernet applications, these resistors are optional.
36
Final
Version :DM9008-DS-F02
June 14, 2000
ENA Module
Oscillator
The oscillator is controlled by a 20 Mhz parallel resonant
crystal connected between X1 and X2. The 20 MHz output of
the oscillator is divided by 2 to generate the 10 MHz transmit
clock for the ENC. The oscillator also provides internal clock
signals to the encoding and decoding circuits. It is
recommended that a crystal meeting the following
specifications be used:
Resonant Frequency . . . . . . . . . . . . . . . . . . . . . . . 20 MHz
Tolerance . . . . . . . . . . . . . . . . . . . . . . . .
±
0.001% at 25
°
C
Stability . . . . . . . . . . . . . . . . . . . .
±
0.005% at 0
°
C to 70
°
C
Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AT CUT
Circuit . . . . . . . . . . . . . . . . . Series or Parallel Resonance
An external 20MHz oscillator may be applied to pin X2 while
pin X1 is connected to ground.
Manchester Encoder
The Manchester encoder accepts NRZ data from the
controller, encodes the data to Manchester format, and
transmits it differentially to the transceiver through the
differential transmit driver.
The differential transmit pair from the secondary of the
isolation transformer drives up to 50 meters of wisted pair AUI
cable. These outputs are source followers which require two
270 ohm pull-down resistors to ground.
Manchester Decoder
The decoder consists of a slicer circuit and a PLL circuit to
recover the receiver clock and data. The differential input must
To prevent noise from falsely triggering the decoder, a squelch
circuit at the input rejects signals with pulse width of less than
30 ns at -300 mV, or signals with levels of less than -175 mV.
Signals more negative than -300 mV with a duration of greater
than 30 ns are decoded. Data become valid typically within 5
bit times. The ENA may tolerate bit jitter of up to 20ns in the
received data. The decoder detects the end of a frame when
no more midbit transitions are detected.
Collision Detector
A transceiver detects collisions on the network and generates
a 10 Mhz signal at the CD
±
input. When these inputs exceed
the squelch requirements (same as the receiver/decoder),
DM9008 uses this signal to back off its current transmission
and reschedule another one.
Loopback Function
When loopback mode 2 is set, the ENA redirects its
transmitted data back into its receive path. This feature
provides a convenient method for testing the whole chip and
system level integrity. The transmit driver and receive input
circuit are disabled in loopback mode.
Traffic LED Driver
DM9008 provides an LED driver in pin 55. When the DM9008
is in transmission or receive mode, this pin will go low for
80ms, then into high impedance state for 50ms to indicate the
presence of traffic on the network. In idle state, it is in high
impedance state.
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PDF描述 |
|---|---|
| DM9008F | ISA/Plug & Play Super Ethernet Contoller |
| DM9081 | 10BASE-T Hub Controller |
| DM9081F | 10BASE-T Hub Controller |
| DM9095 | Twisted-Pair Medium Attachment Unit |
| DM9095L | Twisted-Pair Medium Attachment Unit |
相關(guān)代理商/技術(shù)參數(shù) |
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| DM9008AEP | 制造商:DAVICOM 制造商全稱:DAVICOM 功能描述:Ethernet Controller with General Processor Interface |
| DM9008AEP_06 | 制造商:DAVICOM 制造商全稱:DAVICOM 功能描述:Ethernet Controller with General Processor Interface |
| DM9008AEP_08 | 制造商:DAVICOM 制造商全稱:DAVICOM 功能描述:Ethernet Controller with General Processor Interface |
| DM9008C | 制造商:DAVICOM 制造商全稱:DAVICOM 功能描述:Ethernet Controller With General Processor Interface |
| DM9008CEP | 制造商:DAVICOM 制造商全稱:DAVICOM 功能描述:Ethernet Controller With General Processor Interface |
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