CY7B8392
Ethernet Coax Transceiver Interface
1CY7B8392
Functional Description
The CY7B8392 is a low power coaxial transceiver for Ethernet
10BASE5 and 10BASE2 applications. The device contains all
the circuits required to perform transmit, receive, collision de-
tection, heartbeat generation, jabber timer and attachment
unit interface (AUI) functions. In addition, the CY7B8392 fea-
tures an advanced hybrid collision detection.
The transmitter output is connected directly to a double termi-
nated 50Ω cable.
The CY7B8392 is fabricated with an advanced low power
BiCMOS process. Typical standby current during idle is 25 mA.
Features
•
•
•
•
•
Compliant with IEEE802.3 10BASE5 and 10BASE2
Pin compatible with the popular 8392
Internal squelch circuit to eliminate input noise
Hybrid mode collision detect for extended distance
Automatic AUI port isolation when coaxial connector is
not present
• Low power BiCMOS design
• 16-Pin DIP or 28-Pin PLCC
Logic Block Diagram
RX+
HIGH PASS
EQUALIZATION
CCM
AUI
DRIVER
RX–
RXI
LOW PASS
FILTER
–
LOW PASS
FILTER
+
CARRIER
SENSE
AUI
DRIVER
CD–
CD+
GND
TX+
TX–
–
CDS
RCV
TXO
LOW PASS
FILTER
+
COLLISION
WAVEFORM
SHAPING
+
–
DC/AC
SQUELCH
V
EE
RR+
1K
RR–
REFERENCE
CIRCUIT
10 MHz CLK
OSC
WATCH DOG
TIMER 26 ms
JABBER RESET
TIMER 0.4 sec
TRANSMIT
STATE
MACHINE
RECEIVE
STATE
MACHINE
HBE
8392–1
Pin Configurations
DIP
Top View
CD+
CD–
RX+
V
EE
V
EE
RX–
TX+
TX–
1
2
3
4
5
6
7
8
7B8392
16
15
14
13
12
11
10
9
CDS
TXO
RXI
V
EE
RR–
RR+
GND
HBE
V
EE
(NC)
V
EE
(NC)
V
EE
V
EE
V
EE
(NC)
V
EE
(NC)
V
EE
(NC)
PLCC
Top View
RX+
CD–
CD+
CDS
TXO
NC
RXI
4 3 2 1 28 2726
5
6
7
7B8392
8
9
10
11 1213 14 15 16 1718
RX–
TX+
25
24
23
22
21
20
V
EE
(NC)
V
EE
V
EE
(NC)
V
EE
(NC)
V
EE
V
EE
(NC)
RR–
8392–3
TX–
HBE
GND
GND
RR+
8392–2
Cypress Semiconductor Corporation
Document #: 38-02016 Rev. **
•
3901 North First Street
•
San Jose
•
CA 95134 • 408-943-2600
Revised January 1996
CY7B8392
Pin Description
Pin Number
16-Pin
DIP
1
2
3
6
7
8
9
11
12
14
15
16
28-Pin
PLCC
2
3
4
12
13
14
15
18
19
26
28
1
Pin Name
CD+
CD–
RX+
RX–
TX+
TX–
HBE
RR+
RR–
RXI
TXO
CDS
Description
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
EE
, the heartbeat is disabled.
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.
10
4,5,13
16,17
5–11,
20–25
GND
V
EE
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
CD
. When the measured signal
level is more negative than V
CD
, a collision condition is de-
clared by the CY7B8392 by sending a 10-MHz signal over the
CD+/CD– pair.
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
[1]
. The Heartbeat function
should be disabled by tying the HBE pin to V
EE
for repeater
applications.
Note:
1. BT = Bit Time = 100 ns.
Document #: 38-02016 Rev. **
Page 2 of 8
CY7B8392
Jabber Function
The on-chip watchdog timer prevents the DTE from locking up
a network by transmitting continuously. When the transmission
exceeds the jabber time limit, the Jabber function disables the
transmitter and sends a 10-MHz signal over the CD± pair.
Once the transmitter is in the jabber state, it must remain in the
idle state for 500 ms before it will exit the jabber state.
AUI Function
The CY7B8392 Auto AUI function will isolate the AUI CI port
when coaxial cable is not present. The CY7B8392 monitors
the average DC level at the RXI input and determines if a prop-
erly terminated coaxial segment is attached. While RXI is un-
terminated the AUI port will remain powered down. The AUI
port will only be activated when RXI is connected to a termi-
nated coaxial segment.
When the RXI input becomes unterminated (after power-up),
a 10-MHz signal is transmitted over the CI circuit for 800 ms.
After the transmission of the 10-MHz signal, the CI port is dis-
abled.
This function allows multiple MAUs to be connected to a single
AUI port without having to turn off the coaxial transceiver man-
ually.
Connection Diagram for Standard CY7B8392 Applications
AUI
CABLE
12 to15VDC
DC to DC
CONVERTER
≥
100 mA
+
9V (ISOLATED)
–
510
Ω
510
Ω
510
Ω
NOTE 5
1
COLLISION
PAIR
78
Ω
2
16
15
510
Ω
DTE
NOTE 2
T1 (NOTE 3)
4
13
CD+
5
12
CD–
RX+
1
2
3
16
15
CDS
TXO
RXI
V
EE
RR–
RR+
GND
HBE
8392–4
1KΩ 1%
COAX
RECEIVE
PAIR
78
Ω
NOTE 4
7
TRANSMIT
PAIR
8
10
9
78
Ω
14
CY7B8392
V
EE
4
13
V
EE
5
12
RX– 6
11
TX+
10
7
TX–
9
8
Maximum Ratings
(Above which the useful life may be impaired. For user guide-
lines, not tested.)
Storage Temperature ................................. –65°C to +150°C
Ambient Temperature with
Power Applied ................................................. –0°C to +70°C
Supply Voltage ...............................................................–12V
Input Voltage .................................... GND+0.3V to V
EE
–0.3V
ESD Protection .........................................................2200V
[6]
Operating Range
Range
Commercial
Ambient
Temperature
0°C to +70°C
V
EE
–9V
±
5%
Notes:
2. 78
Ω
resistors not required if AUI cable not present.
3. T1 is a 1:1 pulse transformer, with an inductance of 30 to 100
µ
H.
4. IN916 or equivalent.
5. Resistors may be as small as 510
Ω
; larger values may be used to reduce
power dissipation.
6. HBM measurement exception: HBE and RXI pins ESD protected to
1100V
Document #: 38-02016 Rev. **
Page 3 of 8
CY7B8392
Electrical Characteristics
Over the Operating Range
[7]
Parameter
V
EE
I
EE1
I
EE2
I
MAU
I
TDC
I
TAC
I
CDS
V
IH
V
IL
I
IH
I
IL
V
DIS
V
CD
V
CS
RX, CD
VOB
V
OC
V
TS
R
RXI
R
TXO
R
TX
Supply Voltage
(V
EE
to GND) Non-transmitting
[8]
(V
EE
to GND) Transmitting
Input Bias Current (RXI and T
XO
pin)
Transmitter Output DC Current
Transmitter AC Current
Cable Sense Input Bias Current
HBE input HIGH voltage
HBE input LOW voltage
HBE input HIGH current
HBE input LOW current
AUI Disable Voltage At RXI
Collision Threshold (Receive Mode)
Carrier Sense Threshold
Differential Output Voltage
Differential Output Voltage Imbalance - Idle
Common Mode Voltage
[9]
(DI and CI ports)
Transmitter Squelch Threshold
[10]
Shunt Resistance—Non-transmitting
[11]
Shunt Resistance—Transmitting
[11]
Differential Impedance At TX±
–175
100
10
30
–3.5
–225
–300
–1.45
–0.42
±475
-10
-4.0
–1.53
–1.62
–0.60
±1500
±
40
-4.2
-4.8
300
–2
37
±28
1
3
41
Description
Min.
–8.55
Typ.
–9.0
–25
–70
Max.
–9.45
–35
–80
25
45
Unit
V
mA
mA
µA
mA
mA
µA
V
V
µA
µA
V
V
V
mV
mV
V
mV
kΩ
kΩ
kΩ
Capacitance
Parameter
C
X
Description
Input Capacitance
Test Conditions
Guaranteed by Design
Typ.
1.5
Unit
pF
Notes:
7. Testing is done under test load as defined in AC Test Loads and Waveforms.
8. Not including current through external pulldown resistors.
9. During idle, V
OC
is reduced to minimize the power dissipation across the load resistors connected to RX
±
and CD±.
10. For a minimum pulse width of >40 ns.
11. To measure shunt resistance, the pin (RXI or TXO) is terminated to 0 volts and the current is measured, then the pin is forced to –2 volts and the current is
measured. The resistance is found by:
DV
2V
R = ------- = -------------------------------------
-
-
DI
I 0V
–
I
( ) (
–
2V
)
Document #: 38-02016 Rev. **
Page 4 of 8
CY7B8392
AC Test Loads and Waveforms
TXO
TRANSMIT
TER
OUTPUT
25
Ω
39
Ω
RECEIVER (RX)
COLLISION OUTPUT (CD)
510
Ω
V
EE
510
Ω
50
µ
H
39
Ω
(a)
(b)
8392–5
Switching Characteristics
Over the Operating Range
Parameter
t
RON
t
RONV
t
RD
t
RR
t
RF
t
OS
t
RJ
t
TST
t
TSTV
t
TD
t
TR
t
TF
t
TM
t
TS
t
TON
t
TOFF
t
CON
t
COFF
f
CD
t
CD
t
HON
t
HW
t
JA
t
JR
Description
Receiver Start-Up Delay
First Validly Timed Bit On RX±
Receiver Propagation Delay
Differential Output Rise Time (RX±, CD±)
Differential Output Fall Time (RX±, CD±)
Differential Output Settling Time (VOB =
±
40mV)
Receiver and Cable Total Jitter
Transmitter Start-Up Delay
First Validly Timed Bit On TXO
Transmitter Propagation Delay
Transmitter Output Rise Time (TXO)
Transmitter Fall Time (TXO)
t
TR
and t
TF
Mismatch
Transmit Skew (TXO)
Transmit Turn-On Pulse Width at V
TS
(TX±)
[12]
Transmit Turn-Off Delay
Collision Turn-On Delay
Collision Turn-Off Delay
Collision Frequency
Collision Pulse Width
CD Heartbeat Delay
CD Heartbeat Duration
Jabber Activation Delay
Jabber Reset Time Out
8.5
40
0.6
0.5
20
300
10
50
1.1
1.0
26
420
10
130
20
20
25
25
25
±0.5
±0.5
20
200
7
25
4
4
1
±2
1
2
t
TST
+1
50
30
30
±3
±2
40
300
13
20
12.5
60
1.6
1.5
32
550
Min.
Typ.
2.5
Max.
5
t
RON
+1
50
7
7
Unit
bits
bits
ns
ns
ns
µs
ns
bits
bits
ns
ns
ns
ns
ns
ns
ns
bits
bits
MHz
ns
µs
µs
ms
ms
Notes:
12. For a minimum pulse amplitude of >300 mV.
Document #: 38-02016 Rev. **
Page 5 of 8
