cy7b8392 Cypress Semiconductor Corporation., cy7b8392 Datasheet - Page 2

• Manufacturer Part Number: cy7b8392
• Description: Ethernet Coax Transceiver Interface
• Manufacturer: Cypress Semiconductor Corporation.

Pin Description
CY7B8392 Description
Transmitter
The CY7B8392 transfers Manchester-encoded data from the
AUI port of the DTE (TX+ and TX–) to the coaxial cable. The
output waveform is wave shaped to meet IEEE 802.3 specifi-
cations. For Ethernet compatible applications (10BASE5), an
external isolation diode should be added to further reduce the
coax load capacitance.
The AUI squelch circuit prevents signals with less than 15 ns
pulse width or smaller than 225 mV in amplitude from reaching
the output driver. The squelch circuit also turns the transmitter
off at the end of the packet if the amplitude remains less than
225 mV for more than 190 ns.
Receiver
The CY7B8392 receiver transfers the serial data from the co-
axial cable to the DTE via the balanced differential output (RX+
and RX–). The received signal is amplified and equalized by
the on chip equalizer.
The device also contains an internal squelch function that dis-
criminates noise from valid data. A 4-pole Bessel filter is used
to extract the DC level of the received signal. If the DC level of
the received signal is lower than an internally set squelch
threshold, the CY7B8392 receive function will not be activated.
Collision Detection
The collision detection circuit monitors the signal level on the
coax cable. This signal voltage level is compared against the
collision voltage threshold V
level is more negative than V
clared by the CY7B8392 by sending a 10-MHz signal over the
CD+/CD– pair.
16-Pin
4,5,13
DIP
11
12
14
15
16
10
1
2
3
6
7
8
9
Pin Number
28-Pin
20–25
PLCC
16,17
5–11,
12
13
14
15
18
19
26
28
2
3
4
1
Pin Name
CD
CD
GND
CD+
CD–
HBE
RR+
RR–
TXO
CDS
RX+
RX–
TX+
TX–
V
. When the measured signal
RXI
, a collision condition is de-
EE
AUI Collision Output pins. Differential driver that transmit a 10-MHz signal during
collision events, jabber and CD Heartbeat conditions. Also referred to as CI port.
AUI Receive Output pins. Differential driver that outputs the signal receive from
the line. Also referred to as DI port.
AUI Transmit Input pins. Differential receiver that inputs the signal for transmission
onto the cable.
Heartbeat Enable Pin. When this pin is grounded, the heartbeat is enabled. When
the pin is connected to V
External Resistor. A 1K 1% resistor should be connected between these pins to
establish proper internal operation current.
Receive Input. This pin is connected directly to the coaxial cable.
Transmitter Output. This pin is connected directly (10BASE2 thin wire) or through
a diode to the coaxial cable.
Collision Detect Sense. Ground sense connection for the collision detect circuit.
This pin should be connected separately to the shield to prevent ground drops from
altering the receive mode collision detect threshold.
Positive Power Supply Pin.
Negative Power Supply Pin.
2
Long Cable Application
The IEEE 802.3 standard is designed for 500 meters of Ether-
net cable and 185 meters of thin coax cable (RG58A/U). To
extend the cable segment to 1000 meters and 300 meters of
Ethernet cable and thin coaxial cable respectively, transmit
collision detection mode is required. The disadvantage of or-
dinary transmit collision detection mode is that it will detect
collision only when the station is transmitting; it will not be able
to detect collision of two far-end stations when it is not trans-
mitting. Transmit mode collision detection is not allowed in re-
peater applications.
The CY7B8392 utilizes a hybrid combination of receive and
transmit collision detection. When the device is not transmit-
ting, the unit automatically sets the collision threshold voltage
to the smaller (less negative) receive level. This allows colli-
sion detection of two far end stations while the unit is not trans-
mitting. If the unit enters the transmit mode, the collision de-
tection threshold is automatically changed to the larger (more
negative) transmit collision detection threshold. This feature
eliminates the need for an external voltage divider at the input
of CDS when using the 1000 meters and 300 meters of Ether-
net and thin coaxial cable length, respectively.
Heartbeat Test Function
The Heartbeat Test Function is enabled when the HBE pin is
tied to ground. When enabled, a 10-MHz collision signal is
transmitted to the MAC over the CD+/CD– pair after the trans-
mission of a packet for 10 5BT
should be disabled by tying the HBE pin to V
applications.
EE
Note:
1.
, the heartbeat is disabled.
BT = Bit Time = 100 ns.
Description
[1]
. The Heartbeat function
CY7B8392
EE
for repeater