83C694 ETC, 83C694 Datasheet - Page 17

• Manufacturer Part Number: 83C694
• Description: TWISTED PAIR INTERFACE AND MACHESTER ENCODER/DECODER
• Manufacturer: ETC

83C694D
14
NUMBER
32, 33,
34, 35
PIN
36
37
38
40
42
39
41
VCC
NC
TST
BSR
RX-
RX+
CD-
CD+
MNEMONIC
TABLE 3-1. PIN DESCRIPTION cont.
Positive Supply
Not Connected
Test Input
Bias Resistor
AUI Receive
AUI Collision
SIGNAL NAME
I/O
I
I
I
I
Pin 32 is positive supply to the VCO. Pin 33
is positive supply for digital and transmit cir-
cuits. Pin 34 is positive supply for digital cir-
cuits. Pin 35 is positive supply for receive
circuits.
Do not connect to this pin.
This pin must be tied low.
A resistor from BSR to VCC sets the internal
bias levels. Nominal value is 10K 1% resis-
tor connected externally to +5V. If BSR is tied
low, a low power mode is enabled and trans-
mit/receive is disabled.
In AUI mode, the Manchester encoded data
from an external transceiver is received on
RX+/RX-. After timing recovery and decoding,
it is output to the controller on RXD. With the
standard 78
ferential input must be externally terminated.
This requirement can be satisfied by connect-
ing two 39.2
optional 0.1 F common mode bypass ca-
pacitor as shown in Figure 2-3. Matched ca-
pacitors can also be added to protect the
inputs from external faults.
In AUI mode, a 10 MHz collision presence
signal from an external transceiver is received
on CD+/CD-. The COL pin is then output high.
The collision differential inputs, CD+ and CD-,
must be terminated in the same manner as
the receive inputs, RX+ and RX-. See Figure
2-3 for information on this design.
DESCRIPTION
transceiver AUI cable, the dif-
1% resistors in series with an
PIN DESCRIPTION