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CY7B8392
Ethernet Coax Transceiver Interface
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
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 detection, heartbeat generation, jabber timer and attachment unit interface (AUI) functions. In addition, the CY7B8392 features an advanced hybrid collision detection. The transmitter output is connected directly to a double terminated 50 cable. The CY7B8392 is fabricated with an advanced low power BiCMOS process. Typical standby current during idle is 25 mA.
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
VEE 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+ VEE VEE RX- TX+ TX- 1 2 3 4 5 6 7 8 7B8392 16 15 14 13 12 11 10 9 CDS TXO RXI VEE RR- RR+ GND HBE 8392-3 VEE (NC) VEE (NC) VEE VEE VEE (NC) VEE (NC) VEE (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 VEE (NC) VEE VEE (NC) VEE (NC) VEE VEE (NC) RR- TX- HBE GND GND RR+
8392-2
Cypress Semiconductor Corporation
*
3901 North First Street
*
San Jose
* CA 95134 * 408-943-2600 December 1994 - Revised August 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 VEE, 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 VEE
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 specifications. 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 coaxial 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 discriminates 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 VCD. When the measured signal level is more negative than VCD, a collision condition is declared 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 Ethernet 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 ordinary 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 transmitting. Transmit mode collision detection is not allowed in repeater applications. The CY7B8392 utilizes a hybrid combination of receive and transmit collision detection. When the device is not transmitting, the unit automatically sets the collision threshold voltage to the smaller (less negative) receive level. This allows collision detection of two far end stations while the unit is not transmitting. If the unit enters the transmit mode, the collision detection 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 Ethernet 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 transmission of a packet for 105BT[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.
2
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 properly terminated coaxial segment is attached. While RXI is unterminated the AUI port will remain powered down. The AUI port will only be activated when RXI is connected to a terminated 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 disabled. This function allows multiple MAUs to be connected to a single AUI port without having to turn off the coaxial transceiver manually.
Connection Diagram for Standard CY7B8392 Applications
AUI CABLE
12 to15VDC
DC to DC CONVERTER 100 mA
+ 9V (ISOLATED) - NOTE 5
1 COLLISION PAIR 78 2
510 16 510 510 15 510
DTE
NOTE 2
T1 (NOTE 3) 4 13 CD+ 1 2 3 16 15 CDS TXO RXI VEE RR- RR+ GND HBE
8392-4 1K 1%
COAX
RECEIVE PAIR
78 5 12
CD- RX+
NOTE 4
7 TRANSMIT PAIR 8
10
9
78
14 CY7B8392 VEE 4 13 VEE 5 12 RX- 6 11 TX+ 10 7 TX- 9 8
Maximum Ratings
(Above which the useful life may be impaired. For user guidelines, not tested.) Storage Temperature ................................. -65C to +150C Ambient Temperature with Power Applied ................................................. -0C to +70C Supply Voltage ...............................................................-12V Input Voltage .................................... GND+0.3V to VEE-0.3V ESD Protection .........................................................2200V[6]
Operating Range
Range Commercial Ambient Temperature 0C to +70C VEE -9V 5%
Notes: 2. 78 resistors not required if AUI cable not present. 3. T1 is a 1:1 pulse transformer, with an inductance of 30 to 100 H. 4. IN916 or equivalent. 5. Resistors may be as small as 510; larger values may be used to reduce power dissipation. 6. HBM measurement exception: HBE and RXI pins ESD protected to 1100V
3
CY7B8392
Electrical Characteristics Over the Operating Range[7]
Parameter VEE IEE1 IEE2 IMAU ITDC ITAC ICDS VIH VIL IIH IIL VDIS VCD VCS RX, CD VOB VOC VTS RRXI RTXO RTX Supply Voltage (VEE to GND) Non-transmitting (VEE to GND) Transmitting Input Bias Current (RXI and TXO 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] [8]
Description
Min. -8.55
Typ. -9.0 -25 -70
Max. -9.45 -35 -80 25
Unit V mA mA A mA mA A V
-2 37 28 1 -4.2 41
45
3
-4.8 300 -10 -4.0 -1.45 -0.42 475 -1.53 -1.62 -0.60 1500 40 -3.5 -175
[11]
V A A V V V mV mV V
(DI and CI ports)
[10]
Transmitter Squelch Threshold
-225
-300
mV k k
Shunt Resistance--Non-transmitting Shunt Resistance--Transmitting Differential Impedance At TX
[11]
100 10 30
k
Capacitance
Parameter CX 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, VOC 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 -I ( 0V ) ( -2V )
4
CY7B8392
AC Test Loads and Waveforms
39 TXO TRANSMIT TER OUTPUT 25 RECEIVER (RX) 50 H COLLISION OUTPUT (CD) 510 VEE 510 39
(a)
(b)
8392-5
Switching Characteristics Over the Operating Range
Parameter tRON tRONV tRD tRR tRF tOS tRJ tTST tTSTV tTD tTR tTF tTM tTS tTON tTOFF tCON tCOFF fCD tCD tHON tHW tJA tJR 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) tTR and tTF Mismatch Transmit Skew (TXO) Transmit Turn-On Pulse Width at VTS (TX) 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
[12]
Min.
Typ. 2.5 25 4 4 1 2 1 25
Max. 5 tRON+1 50 7 7
Unit bits bits ns ns ns s ns
2 tTST+1 50 30 30 3 2 40 300 13 20 12.5 60 1.6 1.5 32 550
bits bits ns ns ns ns ns ns ns bits bits MHz ns s s ms ms
20 20
25 25 0.5 0.5
10 130
20 200 7
Notes: 12. For a minimum pulse amplitude of >300 mV.
5
CY7B8392
Switching Waveforms
ReceiverTiming
INPUT TO RXI RX+ RX- tRON
50%
50%
tRD 90% 10% tRR
tRF
8392-6
Transmit Timing
TX+ TX-
vTS tTON
50%
TXO OUTPUT tTST
tTD 90%
50% 10%
tTOFF
tTF
tTR
8392-7
Heartbeat Timing
TX+ TX- tHON CD+ CD-
8392-8
tHW
Collision Timing
INPUT TO RXI 0V VCD (max) -1.75V tCON CD+ CD-
8392-9
-1.2V VCD (min) 1/fCD tCD -6.8V tCOFF
Jabber Timing
TX+ TX- tJA TXO tJR CD+ CD-
8392-10
6
CY7B8392
Ordering Information
Ordering Code CY7B8392-JC CY7B8392-PC Document #: 38-00430-B Package Name J64 P1 Package Type 28-Lead Plastic Leaded Chip Carrier 16-Lead (300-Mil) Molded DIP Operating Range Commercial
Package Diagrams
28-Lead Plastic Leaded Chip Carrier J64
16-Lead (300-Mil) Molded DIP P1
(c) Cypress Semiconductor Corporation, 1996. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of any circuitry other than circuitry embodied in a Cypress Semiconductor product. Nor does it convey or imply any license under patent or other rights. Cypress Semiconductor does not authorize its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress Semiconductor products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress Semiconductor against all charges.

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