NE83C92 查看數據表（PDF） - Philips Electronics
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NE83C92 Datasheet PDF : 9 Pages
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Philips Semiconductors
Low-power coaxial Ethernet transceiver
Product specification
NE83C92
POR/Under Voltage Lockout/AUI Selection
The transmit and receive squelch circuits of the NE83C92 remain
active if the absolute value of VEE is less than the threshold for
under voltage lockout, VUVL. This prevents glitches from appearing
on either the AUI or coaxial cable during power up and power down.
There is no collision announcement during power up and the
transceiver waits for 400ms before becoming enabled.
If RXI is disconnected from the coaxial cable after power-up, its
voltage will fall towards VEE. If the absolute value of this voltage
exceeds the AUI disable voltage, VDIS, for longer than 800ms, the
transmit and receive squelch circuits remain active and, in addition,
the AUI drivers become high impedance. This permits AUI
connections to be hard wired together, e.g., the coaxial transceiver
and 10BASE-T transceiver, with the signal path determined by
which transceiver is connected to its external cable.
There is a 400ms collision announcement on disconnecting RXI, but
there is no announcement on re-connection. This feature can be
disabled by pulling RXI up with a 200kΩ to ground.
Detection of Coaxial Cable Faults
In the NE83C92 there is no internal loopback path from the TX
inputs to the RX outputs. This means that, when the local DTE is
transmitting, the signal will only be present at the receiver outputs
RX+ and RX– if it appears on the coaxial cable and is larger than
the receiver squelch threshold VRS. If a short circuit fault condition
occurs at the cable connector to the CTI, then no signal will appear
at the receiver outputs.
In the case of an open circuit at the coaxial cable connector there
will also be no signal at the receiver outputs due to the AUI disabling
mode of the NE83Q92. However, a heartbeat signal will be present
following a transmission attempt for the short circuit condition, but
not for the open circuit.
A coaxial cable with only a single 50Ω termination will generate a
collision not only at every transmission attempt, but also for every
reception attempt due to the receive mode collision detection of the
NE83C92.
AUI
CABLE
12 TO 15V DC
DC TO DC
CONVERTER
<200mA
+
9V (ISOLATED)
–
500Ω
(NOTE 4)
1
16
500Ω
COLLISION
PAIR
78Ω
2
15
500Ω
500Ω
(NOTE 3)
RECEIVE
PAIR
78Ω
TRANSMIT
PAIR
T1 (NOTE 1)
4
13
5
12
7
10
8
9
78Ω
CD+
1
16
CD–
2
15
RX+
3
14
NE83C92
VEE
4
13
VEE
5
RX–
6
TX+
7
TX–
8
CTI 12
11
10
9
CDS
TXO
(NOTE 2)
RXI
VEE
RR–
RR+ 1kΩ 1%
200kΩ
GND
HBE
(NOTE 5)
NOTES:
1. T1 is a 1:1 pulse transformer, with an inductance of 30 to 100µH.
2. IN916 or equivalent for Ethernet, not required for Thin Ethernet.
3. 78Ω resistors not required if AUI cable not present.
4. Not required for optimal integrated/local MAU application (No AUI cable, see Note 3), minimum current consumption.
5. Install 200kΩ to disable the 400ms collision announcement when disconnecting cable.
COAX
SD00309
1995 May 1
Figure 1. Connection Diagram for Standard 8392 Applications
7
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