Philips Semiconductors

Product specification

NE83C92

Low-power coaxial Ethernet transceiver

1995 May 1

7

POR/Under Voltage Lockout/AUI Selection

The transmit and receive squelch circuits of the NE83C92 remain

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 200k

Ω 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

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 50

Ω 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.

CD+

CD–

RX+

VEE

VEE

RX–

TX+

TX–

HBE

GND

RR+

VEE

RXI

TXO

CDS

RR–

500

Ω

500

Ω

500

Ω

500

Ω

+

9V (ISOLATED)

–

DC TO DC

CONVERTER

<200mA

78

Ω

TRANSMIT

PAIR

RECEIVE

PAIR

COLLISION

PAIR

12 TO 15V DC

1k

Ω 1%

(NOTE 2)

NOTES:

1. T1 is a 1:1 pulse transformer, with an inductance of 30 to 100

µH.

2. IN916 or equivalent for Ethernet, not required for Thin Ethernet.

3. 78

Ω 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 200k

Ω to disable the 400ms collision announcement when disconnecting cable.

78

Ω

78

Ω

NE83C92

CTI

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

1

2

4

5

7

8

16

15

13

12

10

9

T1 (NOTE 1)

COAX

AUI

CABLE

(NOTE 3)

SD00309

(NOTE 4)

200k

Ω

(NOTE 5)

Figure 1. Connection Diagram for Standard 8392 Applications