Ethernet Coax Transceiver Interface 1CY7B8392 Functional Description
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CY7B8392 Ethernet Coax Transceiver Interface 1CY7B8392 Functional Description Features The CY7B8392 is a low power coaxial transceiver for Ethernet 10BASE5 and 10BASE2 applications. The device contains all • Compliant with IEEE802.3 10BASE5 and 10BASE2 the circuits required to perform transmit, receive, collision de- • Pin compatible with the popular 8392 tection, heartbeat generation, jabber timer and attachment • Internal squelch circuit to eliminate input noise unit interface (AUI) functions. In addition, the CY7B8392 fea- • Hybrid mode collision detect for extended distance tures an advanced hybrid collision detection. • Automatic AUI port isolation when coaxial connector is The transmitter output is connected directly to a double termi- not present nated 50Ω cable. • Low power BiCMOS design The CY7B8392 is fabricated with an advanced low power • 16-Pin DIP or 28-Pin PLCC BiCMOS process. Typical standby current during idle is 25 mA. Logic Block Diagram RX+ HIGH PASS AUI CCM EQUALIZATION DRIVER RX– RXI LOW PASS FILTER CD+ AUI GND – CARRIER DRIVER LOW PASS SENSE CD– FILTER + TX+ TX– – COLLISION CDS LOW PASS + RCV FILTER TXO WAVEFORM + DC/AC SHAPING SQUELCH – VEE 10 MHz CLK WATCHDOG JABBER RESET OSC TIMER26 ms TIMER0.4 sec RR+ REFERENCE 1K CIRCUIT TRANSMIT RECEIVE RR– STATE STATE MACHINE MACHINE HBE 8392–1 Pin Configurations PLCC DIP Top View Top View – RX+ CD CD+ CDS NC RXI TXO CD+ 1 16 CDS 432 1 28 2726 CD– 2 15 TXO VEE (NC) 5 25 VEE (NC) RX+ 3 14 RXI VEE (NC) 6 24 VEE V VEE 7 23 VEE (NC) EE 4 13 VEE 7B8392 7B8392 VEE 8 22 VEE (NC) VEE 5 12 RR– VEE (NC) 9 21 VEE RX– 6 11 RR+ VEE (NC) 10 20 VEE (NC) TX+ 7 10 GND VEE (NC) 11 121314 15 16 1718 RR– TX– 8 9 HBE – – TX+ TX RX 8392–3 RR+ HBE GND GND 8392–2 Cypress Semiconductor Corporation • 3901 North First Street • San Jose • CA 95134 • 408-943-2600 Document #: 38-02016 Rev. ** Revised January 1996 CY7B8392 Pin Description Pin Number 16-Pin 28-Pin DIP PLCC Pin Name Description 1 2 CD+ AUI Collision Output pins. Differential driver that transmit a 10-MHz signal during 2 3 CD– collision events, jabber and CD Heartbeat conditions. Also referred to as CI port. 3 4 RX+ AUI Receive Output pins. Differential driver that outputs the signal receive from 6 12 RX– the line. Also referred to as DI port. 7 13 TX+ AUI Transmit Input pins. Differential receiver that inputs the signal for transmission 8 14 TX– onto the cable. 9 15 HBE Heartbeat Enable Pin. When this pin is grounded, the heartbeat is enabled. When the pin is connected to VEE, the heartbeat is disabled. 11 18 RR+ External Resistor. A 1K 1% resistor should be connected between these pins to 12 19 RR– establish proper internal operation current. 14 26 RXI Receive Input. This pin is connected directly to the coaxial cable. 15 28 TXO Transmitter Output. This pin is connected directly (10BASE2 thin wire) or through a diode to the coaxial cable. 16 1 CDS 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. 10 16,17 GND Positive Power Supply Pin. 4,5,13 5–11, VEE Negative Power Supply Pin. 20–25 CY7B8392 Description Long Cable Application The IEEE 802.3 standard is designed for 500 meters of Ether- Transmitter net cable and 185 meters of thin coax cable (RG58A/U). To The CY7B8392 transfers Manchester-encoded data from the extend the cable segment to 1000 meters and 300 meters of AUI port of the DTE (TX+ and TX–) to the coaxial cable. The Ethernet cable and thin coaxial cable respectively, transmit output waveform is wave shaped to meet IEEE 802.3 specifi- collision detection mode is required. The disadvantage of or- cations. For Ethernet compatible applications (10BASE5), an dinary transmit collision detection mode is that it will detect external isolation diode should be added to further reduce the collision only when the station is transmitting; it will not be able coax load capacitance. to detect collision of two far-end stations when it is not trans- The AUI squelch circuit prevents signals with less than 15 ns mitting. Transmit mode collision detection is not allowed in re- pulse width or smaller than 225 mV in amplitude from reaching peater applications. the output driver. The squelch circuit also turns the transmitter The CY7B8392 utilizes a hybrid combination of receive and off at the end of the packet if the amplitude remains less than transmit collision detection. When the device is not transmit- 225 mV for more than 190 ns. ting, the unit automatically sets the collision threshold voltage to the smaller (less negative) receive level. This allows colli- Receiver sion detection of two far end stations while the unit is not trans- The CY7B8392 receiver transfers the serial data from the co- mitting. If the unit enters the transmit mode, the collision de- axial cable to the DTE via the balanced differential output (RX+ tection threshold is automatically changed to the larger (more and RX–). The received signal is amplified and equalized by negative) transmit collision detection threshold. This feature the on chip equalizer. eliminates the need for an external voltage divider at the input of CDS when using the 1000 meters and 300 meters of Ether- The device also contains an internal squelch function that dis- net and thin coaxial cable length, respectively. 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 Heartbeat Test Function the received signal is lower than an internally set squelch threshold, the CY7B8392 receive function will not be activated. The Heartbeat Test Function is enabled when the HBE pin is tied to ground. When enabled, a 10-MHz collision signal is Collision Detection transmitted to the MAC over the CD+/CD– pair after the trans- mission of a packet for 10±5BT[1]. The Heartbeat function The collision detection circuit monitors the signal level on the should be disabled by tying the HBE pin to VEE for repeater coax cable. This signal voltage level is compared against the applications. collision voltage threshold VCD. When the measured signal level is more negative than VCD, a collision condition is de- clared by the CY7B8392 by sending a 10-MHz signal over the Note: 1. BT = Bit Time = 100 ns. CD+/CD– pair. Document #: 38-02016 Rev. ** Page 2 of 8 CY7B8392 Jabber Function erly terminated coaxial segment is attached. While RXI is un- The on-chip watchdog timer prevents the DTE from locking up terminated the AUI port will remain powered down. The AUI a network by transmitting continuously. When the transmission port will only be activated when RXI is connected to a termi- exceeds the jabber time limit, the Jabber function disables the nated coaxial segment. transmitter and sends a 10-MHz signal over the CD± pair. When the RXI input becomes unterminated (after power-up), Once the transmitter is in the jabber state, it must remain in the a 10-MHz signal is transmitted over the CI circuit for 800 ms. idle state for 500 ms before it will exit the jabber state. After the transmission of the 10-MHz signal, the CI port is dis- abled. AUI Function This function allows multiple MAUs to be connected to a single The CY7B8392 Auto AUI function will isolate the AUI CI port AUI port without having to turn off the coaxial transceiver man- when coaxial cable is not present. The CY7B8392 monitors ually. the average DC level at the RXI input and determines if a prop- Connection Diagram for Standard CY7B8392 Applications AUI CABLE + 12 to15VDC DC to DC CONVERTER 9V (ISOLATED) ≥ 100 mA – NOTE 5 510Ω 1 16 510Ω COLLISION PAIR 78Ω 510Ω 2 15 510Ω NOTE 2 T1 (NOTE 3) DTE 4 13 COAX CD+ CDS RECEIVE 1 16 PAIR 78Ω CD– TXO NOTE 4 5 12 2 15 RX+ RXI 3 14 CY7B8392 V V EE 4 13 EE V RR– EE 5 12 7 10 RX– RR+ 1KΩ 1% 6 11 TRANSMIT TX+ GND PAIR 7 10 8 9 78Ω TX– HBE 8 9 8392–4 Maximum Ratings Operating Range (Above which the useful life may be impaired. For user guide- lines, not tested.) Ambient Range Temperature VEE Storage Temperature ................................. –65°C to +150°C Commercial 0°C to +70°C –9V ± 5% Ambient Temperature with ° ° Notes: Power Applied ................................................. –0 C to +70 C 2. 78Ω resistors not required if AUI cable not present. 3. T1 is a 1:1 pulse transformer, with an inductance of 30 to 100 µH. Supply Voltage ...............................................................–12V 4. IN916 or equivalent. 5. Resistors may be as small as 510Ω; larger values may be used to reduce Input Voltage.................................... GND+0.3V to VEE–0.3V power dissipation. [6] 6. HBM measurement exception: HBE and RXI pins ESD protected to ESD Protection .........................................................2200V 1100V Document #: 38-02016 Rev. ** Page 3 of 8 CY7B8392 Electrical Characteristics Over the Operating Range[7] Parameter Description Min. Typ. Max. Unit VEE Supply Voltage –8.55 –9.0 –9.45 V [8] IEE1 (VEE to GND) Non-transmitting –25 –35 mA IEE2 (VEE to GND) Transmitting –70 –80 mA µ IMAU Input Bias Current (RXI and TXO pin) –2 25 A ITDC Transmitter Output DC Current 37 41 45 mA ± ITAC Transmitter AC Current 28 mA µ ICDS Cable Sense Input Bias Current 1 3 A VIH HBE input HIGH voltage -4.2 V VIL HBE input LOW voltage -4.8 V µ IIH HBE input HIGH current 300 A µ IIL HBE input LOW current -10 A VDIS AUI Disable Voltage At RXI -4.0 V VCD Collision Threshold (Receive Mode) –1.45 –1.53 –1.62 V VCS Carrier Sense Threshold –0.42 –0.60 V RX, CD Differential Output Voltage ±475 ±1500 mV VOB Differential Output Voltage Imbalance - Idle ± 40 mV [9] VOC Common Mode Voltage (DI and CI ports) –3.5 V [10] VTS Transmitter Squelch Threshold –175 –225 –300 mV [11] Ω RRXI Shunt Resistance—Non-transmitting 100 k [11] Ω RTXO Shunt Resistance—Transmitting 10 k ± Ω RTX Differential Impedance At TX 30 k Capacitance Parameter Description Test Conditions Typ.