Philips Semiconductors Product specification Coaxial transceiver interface for Ethernet/Thin Ethernet DESCRIPTION NE8392C PIN CONFIGURATION The NE8392C Coaxial Transceiver Interface (CTI) is a bipolar coaxial line driver/receiver for Ethernet (10base5) and Thin Ethernet (10base2) local area networks. The CTI is connected between the coaxial cable and the Data Terminal Equipment (DTE) and consists of a receiver, transmitter, receive-mode collision detector, heartbeat generator and jabber timer (see Block Diagram). The transmitter output connects directly to a doubly terminated 50Ω cable, while the receiver output, collision detector output and transmitter input are connected to the DTE through isolation transformers. Isolation between the CTI and the DTE is an IEEE 802.3 requirement that can be met on signal lines by using a set of pulse transformers normally available in a standard 16-pin DIP. Power isolation for the CTI is achieved using DC-to-DC conversion through a power transformer (see Figure 1, Connection Diagram). N PACKAGE 1 CD– 2 15 TXO 3 14 VEE 4 13 VEE VEE 5 12 RR– RX– 6 11 RR+ TX+ 7 10 GND TX– 8 RX+ During transmission the jabber timer is initiated to disable the CTI transmitter in the event of a longer than legal length data packet. Receive-mode collision detection circuitry monitors the signals on the coaxial cable to determine the presence of colliding packets and signals the DTE in the event of a collision. At the end of every transmission the heartbeat generator creates a pseudo collision for a short time to ensure that the collision circuitry is functioning correctly. The heartbeat function can be disabled for repeater applications. 16 CDS CD+ 9 RXI HBE 2 1 RXI CDS 3 N/C CD+ 4 TXO RX+ CD– A PACKAGE 28 27 26 V EE 5 V EE 6 V EE 7 V EE 8 V EE 9 V EE 10 V EE 11 24 23 22 21 20 19 RR+ GND HBE • Compatible with Ethernet II IEEE 802.3 10base5 and 10base2, V EE V EE V EE V EE V EE V EE RR– 14 15 16 17 18 GND RX– FEATURES TX+ 12 13 TX– The CTI is normally part of a three chip set that implements a complete Ethernet/ Thin Ethernet network interface for a DTE (see Figure 2, Interface Diagram). The other chips are a Serial Network Interface (SNI) and a Network Interface Controller (NIC). The SNI provides Manchester Encoding and Decoding while the NIC handles the media access protocol and buffer management tasks. 25 SD00283 and ISO 8802/3 interface specifications • 100% drop-in compatible with industry standard 8392 sockets • Integrates all transceiver electronics except signal and power • On-chip precision voltage reference for receive mode collision detection • Squelch circuitry on all signal inputs rejects noise • Full ESD protection • Standard 16-pin DIP and 28-pin PLCC packages • Power-on reset prevents glitches on coaxial cable during power isolation • Only one external resistor required for setting coaxial signaling current • Jabber timer function integrated on chip • Heartbeat generator can be externally disabled for operation as up. IEEE 802.3 compatible repeaters • Also available in advanced low-power BiCMOS technology. (See selection chart and data sheets for the NE83C92, NE83Q92 or NE83Q93 for appropriate optimal usages) ORDERING INFORMATION TEMPERATURE RANGE ORDER CODE DWG # 16-Pin Plastic Dual In-Line Package (DIP) DESCRIPTION 0 to +70°C NE8392CN SOT28-4 28-Pin Plastic Lead Chip Carrier (PLCC) 0 to +70°C NE8392CA SOT261-3 1995 May 1 1 853-1693 15180 Philips Semiconductors Product specification Coaxial transceiver interface for Ethernet/Thin Ethernet NE8392C PIN DESCRIPTIONS PIN NO. N PKG PIN NO. PLCC SYMBOL 1 2 2 3 CD+ CD– Collision Outputs. Balanced differential line driver outputs which send a 10MHz oscillation signal to the DTE in the event of a collision, jabber interrupt or heartbeat test. 3 6 4 12 RX+ RX– Receiver Outputs. Balanced differential line driver outputs which send the received signal to the DTE. 7 8 13 14 TX+ TX– Transmitter Inputs. Balanced differential line receiver inputs which accept the transmission signal from the DTE and apply it to the coaxial cable at TXO once it meets Tx squelch threshold. 9 15 HBE Heartbeat Enable. The heartbeat function is disabled when this pin is connected to VEE and enabled when connected to GND or left floating. 11 12 18 19 RR+ RR– External Resistor. A 1kΩ (1%) resistor connected between these pins establishes the signaling current at TXO. RR– is internally connected to VEE. 14 26 RXI Receiver Input. This pin is connected directly to the coaxial cable. Received signals are equalized, amplified, and sent to the DTE through the RX+ pins once it meets Rx squelch threshold. 15 28 TXO Transmitter Output. This pin is connected directly (Thin Ethernet) or through an external isolating diode (Ethernet) to the coaxial cable. 16 1 CDS Collision Detect Sense. Ground sense connection for the collision detection circuitry. This pin should be directly connected to the coaxial cable shield to prevent ground drops affecting the collision threshold voltage. 10 16 17 GND Positive Supply Pin. 4 5 13 5 to 11 20 to 25 VEE Negative supply pins. These pins also serve as a low thermal resistance path for extracting heat from the die. They should, therefore, be connected to a large metal area on the PC board. DESCRIPTION NOTE: 1. The IEEE 802.3 name for CD is CI; for RX is DI; for TX is DO. ABSOLUTE MAXIMUM RATINGS SYMBOL VEE VIN PARAMETER Supply voltage1 Voltage at any input1 TSTG Storage temperature range TSOLD Lead soldering temperature (10sec.) temperature2 TJ Recommended max junction θJA Thermal impedance (N and A packages) RATING UNIT –12 V 0 to –12 V –65 to +150 °C +300 °C +130 °C 60 °C/W NOTE: 1. 100% measured in production. 2. The junction temperature is calculated from the following expression: TJ = TA + θJA [VEE (0.08 + n x 0.05/100) + 8(VEE –2) / R] where TA = Ambient temperature in °C. θJA = Thermal resistance of package. VEE = Normal operating supply voltage in volts. n = Percentage transmitter duty cycle. R = Pull down resistors on the RX and CD pins in Ω. The N package is specially designed to have a low θJA by directly connecting the four center Pins 4, 5, 12, and 13 to the die attachment area. These four pins then provide a conductive heat flow path from the die to the PCB where they should be soldered to a large area VEE track. For the A package, Pins 5 to 11 and 19 to 25 should similarly be soldered to a large area VEE and rack. 1995 May 1 2 Philips Semiconductors Product specification Coaxial transceiver interface for Ethernet/Thin Ethernet NE8392C BLOCK DIAGRAM DTE INTERFACE COAX CABLE RXI BUFFER LINE DRIVER RECEIVE PAIR (RX+, RX–) RECEIVER EQUALIZER 4–POLE BESSEL LOW PASS FILTER TXO RECEIVER AC–DC SQUELCH TRANSMIT PAIR (TX+, TX–) TRANSMITTER CDS SENSE BUFFER TRANSMITTER SQUELCH HEARTBEAT ENABLE COLLISION COMPARATOR & HEARTBEAT GENERATOR COLLISION PAIR (CD+, CD–) 10MHz OSC JABBER TIMER LINE DRIVER SD00274 1995 May 1 3 Philips Semiconductors Product specification Coaxial transceiver interface for Ethernet/Thin Ethernet ELECTRICAL CHARACTERISTICS VEE = –9V +5%; TA = 0°C to +70°C unless otherwise specified1,2. NE8392C No external isolation LIMITS SYMBOL VPOR IEE PARAMETER TEST CONDITIONS MIN TYP MAX Power–on reset voltage. Transmitter disabled for |VEE| < |VPOR| –6.5 Supply current non–transmitting –80 –130 Supply current transmitting –125 –180 IRXI Receive input bias current VRXI = 0V ICDS Cable sense input bias current VCDS = 0V VIH HBE input HIGH voltage VIL HBE input LOW voltage IIH HBE input HIGH current VHBE = 0V IIL HBE input LOW current VHBE = VEE –2 +2 UNIT V mA +25 µA +6 µA VEE +1.4 V VEE +0.4 V 250 500 µA –500 –1000 µA ITDC Transmit output DC current level3 –37 –45 mA ITAC Transmit output AC current level3 ±28 ±ITDC mA ITX10 Transmit current –250 +250 µA –3.7 V –1580 mV ±1200 mV +40 mV VTCOM Transmitter output voltage VTXO = –10V –41 compliance4 VCD Collision threshold5 VOD Differential output voltage – non idle at RX+ and CD+6 VOB Differential output voltage imbalance – idle at RX+ and CD+7 VOC Output common mode voltage at RX± and CD± VRS Receiver squelch threshold Measured by applying DC voltage at RXI –1450 –1530 ±600 –1.5 –2 –2.5 V VRXI average DC –130 –250 –370 mV (VTX+ – VTX–) peak –175 –225 –300 mV VTS Transmitter squelch threshold RRXI Shunt resistance at RXI non–transmitting CRXI Input capacitance at RXI 2 pF RTXO Shunt resistance at TXO transmitting 10 kΩ 100 kΩ NOTES: 1. Currents flowing into device pins are positive. All voltages are referenced to ground unless otherwise specified. For ease of interpretation, the parameter limit that appears in the MAX column is the largest value of the parameter, irrespective of sign. Similarly, the value in the MIN column is the smallest value of the parameter, irrespective of sign. 2. All typicals are for VEE = –9V and TA = 27°C. 3. ITDC is measured as (VMAX + VMIN)/(2 x 25) where VMAX and VMIN are the max and min voltages at TXO with a 25Ω load between TXO and GND. ITAC is measured as (VMAX – VMIN)/(2 x 25). 4. The TXO pin shall continue to sink at least ITDC min when the idle (no signal) voltage on this pin is –3.7V. 5. Collision threshold for an AC signal is within 10% of VCD. 6. Measured on secondary side of isolation transformer (see Connection Diagram, Figure 1). The transformer has a 1:1 turns ratio with an inductance between 30 and 100µH at 5MHz. 7. Measured as the voltage difference between the RX pins or the CD pins with the transformer removed. 1995 May 1 4 Philips Semiconductors Product specification Coaxial transceiver interface for Ethernet/Thin Ethernet NE8392C TIMING CHARACTERISTICS VEE = –9V +5%; TA = 0 to 70°C, unless otherwise specified1. No external isolation diode on TXO. SYMBOL PARAMETER TEST CONDITIONS tRON Receiver start up delay RXI to RX± (Figure 3) First received bit on RX± VRXI = –2V peak LIMITS MIN TYP MAX 5 First validly timed bit on RX± UNIT bits tRON +2 tRD Receiver prop. delay RXI to RX± tRR Differential output rise time on RX± and CD±2,3 VRXI = –2V peak 5 ns tRF Differential output fall time on RX± and CD±2,3 5 ns tOS Differential output settling time on RX± and CD± to VOB = 40mV2 (see Figure 4) 1 µs tRJ Receiver and cable total jitter ±3 ns tRHI Receiver high to idle time tRM Rise and fall time matching on RX± and CD± Measured to +210mV 150 tRF – tRR Transmitter start–up delay TX± to TXO (Figure 5) tTST 35 50 850 0.4 1 First validly timed bit ns ns VTX± = –1V peak First transmitted bit on TXO ns 2 bits tTST + 2 tTD Transmitter prop delay TX± to TXO (see Figure 5) tTR Transmitter rise time 10% to 90% (see Figure 5) 25 ns tTF Transmitter fall time 10% to 90% (see Figure 5) 25 ns tTM tTF – tTR mismatch ±2 ns tTS Transmitter added skew4 ±2 VTX± = 1V peak 35 tTON Transmitter turn on pulse width (see Figure 5) VTX± = 1V peak 10 tTOFF Transmitter turn off pulse width (see Figure 5) VTX± = 1V peak 150 tCON Collision turn on delay (see Figure 6) tCOFF 50 ns 40 250 ns ns 340 ns 0V to –2V step at RXI 13 bits Collision turn off delay (see Figure 6) –2V to 0V step at RXI 16 bits tCHI Collision high to idle time (see Figure 6) Measured to +210mV fCD Collision frequency (see Figure 6) tCP 150 8.0 10 850 ns 12.5 MHz Collision signal pulse width (see Figure 6) 35 70 ns tHON Heartbeat turn on delay (see Figure 7) 0.6 1.6 µs tHW Heartbeat test duration (see Figure 7) 0.5 1.5 µs tJA Jabber activation delay measured from TX± to CD± (see Figure 8) 20 60 ms tJR Jabber reset delay measured from TX± to CD± (see Figure 8) 250 750 ms NOTES: 1. All typicals are for VEE = –9V and TA = 27°C. 2. Measured on secondary side of isolation transformer (see Figure 1, Connection Diagram). The transformer has a 1:1 turn ratio with an inductance between 30 and 100µH at 5MHz. 3. The rise and fall times are measured as the time required for the differential voltage to change from –225mV to +225mV, or +225mV to –225mV, respectively. 4. Difference in propagation delay between rising and falling edges at TXO. for collision circuitry functionality at the end of every transmission. FUNCTIONAL DESCRIPTION The NE8392C contains four main functional blocks (see Block Diagram). These are: d. The jabber timer which disables the transmitter in the event of a longer than legal length data packet. a. The receiver which takes data from the coaxial cable and sends it to the DTE. Receiver Functions b. The transmitter which receives data from the DTE and sends it onto the coaxial cable. The receiver consists of an input buffer, a cable equalizer, a 4-pole Bessel low pass filter, a squelch circuit and a differential line driver. c. The collision detection and heartbeat generation circuitry which indicates to the DTE any collision on the coaxial cable and tests The buffer provides high input resistance and low input capacitance to minimize loading and reflections on the coaxial cable. 1995 May 1 5 Philips Semiconductors Product specification Coaxial transceiver interface for Ethernet/Thin Ethernet signals. This is the only detection scheme allowed by the IEEE 802.3 standard for both repeater and non-repeater nodes. The equalizer is a high pass filter that compensates for the low pass effect of the coaxial cable and results in a flatband response over all signal frequencies to minimize signal distortion. The collision circuitry consists of the 4-pole Bessel low pass filter, a comparator, a precision voltage reference that sets up the collision threshold, a heartbeat generator, a 10MHz oscillator, and a differential line driver. The 4-pole Bessel low pass filter extracts the average DC voltage level on the coaxial cable for use by the receiver squelch and collision detection circuits. The collision comparator monitors the DC level at the output of the low pass filter and enables the line driver if it is more negative than the collision threshold. A collision condition is indicated to the DTE by a 10MHz oscillation signal at the CD outputs and typically occurs within 700ns of the onset of the collision. The collision signal begins with a negative-going pulse and ends with a continuous high-to-idle state longer than 170ns. Figure 6 illustrates collision timing. The receiver squelch circuit prevents noise on the coaxial cable from falsely triggering the receiver in the absence of a true signal. At the beginning of a packet, the receiver turns on when the DC level from the low pass filter is lower than the DC squelch threshold. For normal signal levels this will take less than 500ns, or 5 bits. However, at the end of a packet, a fast receiver turn off is needed to reject both dribble bits on the coaxial cable and spurious responses due to settling of the on-chip bandpass filter. This is accomplished by an AC timing circuit that disables the receiver if the signal level on the coaxial cable remains high for typically 250ns and only enables the receiver again after approximately 1µs. Figures 3 and 4 illustrate receiver timing. At the end of every transmission, the heartbeat generator creates a pseudo collision to ensure that the collision circuitry is properly functioning. This pseudo collision consists of a 1µs burst of 10MHz oscillation at the line driver outputs approximately 1µs after the end of the transmission. The heartbeat function can be disabled externally by connecting the HBE (heartbeat enable) to VEE. This allows the CTI to be used in repeater applications. Figure 7 illustrates heartbeat timing. The differential line driver provides typically ±900mV signals to the DTE with less than 7ns rise and fall times. When in idle state (no received signal) its outputs provide <20mV differential voltage offset to minimize DC standing current in the isolation transformer. The line driver outputs are emitter followers and, for Ethernet applications where they drive a 78Ω transmission line, require a 500Ω pull-down resistor to VEE. For Thin Ethernet applications where the AUI cable is not used, the pull-down resistor can be increased to 1.5kΩ to save power consumption. As with the receiver outputs, the collision outputs also require a pull down resistor to VEE and maintain <20mV differential voltage offset in the idle state to minimize DC standing current in the isolation transformers. Jabber Functions The jabber timer monitors the transmitter and inhibits transmission if it is active for longer than typically 30ms. The jabber circuit then enables the collision outputs for the remainder of the data packet and for typically 450ns (unjab time) after it has ended. At this point the transmitter becomes uninhibited. Figure 8 illustrates jabber timing. Transmitter Functions The transmitter has differential inputs and an open collector current driver output. The differential input common mode voltage is established by the CTI and should not be altered by external circuitry. Controlled rise and fall times of 25ns (+5ns) minimize higher harmonic components in the transmitted spectrum, while matching of these rise and fall times to typically 2ns minimizes signal jitter. The drive current levels of the CTI are set by an on-chip bandgap voltage reference and an external 1% resistor. An on-chip isolation diode is provided to reduce the transmitter’s coaxial cable load capacitance. For Thin Ethernet applications, no further external isolation diode is required, since the NE8392C meets the capacitive loading specifications. For Ethernet applications a further external diode should be added to reduce loading capacitance. Detection of Coaxial Cable Faults In the NE8392C there is no internal loopback path from the TX inputs to the RX outputs. This means that, when the local DTE is transmitting, the signal will only be present at the receiver outputs RX+ and RX– if it appears on the coaxial cable and is larger than the receiver squelch threshold VRS. If a short circuit fault condition occurs at the cable connector to the CTI, then no signal will appear at the receiver outputs. An intelligent DTE can, therefore, detect this fault. If the fault is an open circuit, then a continuous collision signal will be sent to the DTE, provided the average DC voltage at the RXI pin is greater than the typical collision threshold of –1.53V. The transmitter squelch circuit ensures that the transmitter can only be enabled by negative-going differential signals of typically greater than 225mV in magnitude and 15ns in duration. The transmitter will be disabled at the end of a packet if there are no negative going signals of greater than 225mV for more than typically 250ns. Figure 5 illustrates transmitter timing. If a short or open circuit occurs elsewhere on the coaxial cable, the resulting reflections can result in an impedance at the CTI of any value between a short circuit and 50Ω, depending on the distance of the CTI from the fault. The upper limit of 50Ω results from the fact that the coaxial cable is terminated in 50Ω at both ends. Faults on the cable itself are, therefore, not guaranteed to be detected by simply monitoring the RX and CD pins when in the transmit mode, and more sophisticated schemes may be necessary. Collision Functions The collision detection scheme implemented in the NE8392C is receive mode detection, which detects a collision between any two stations on the network with certainty at all times, irrespective of whether or not the local DTE is producing one of the colliding 1995 May 1 NE8392C 6 Philips Semiconductors Product specification Coaxial transceiver interface for Ethernet/Thin Ethernet NE8392C AUI CABLE 12 TO 15V DC + DC TO DC CONVERTER 9V (ISOLATED) – (NOTE 4) 500Ω 16 1 COLLISION PAIR 500Ω 78Ω 500Ω 15 2 DTE 500Ω T1 (NOTE 1) (NOTE 3) COAX 13 4 CD+ RECEIVE PAIR 78Ω 1 16 2 15 CD– 12 5 RX+ 3 VEE1 VEE2 10 7 NE8392C 14 13 4 CTI 8 6 11 7 10 VEE3 1K 1% 8 9 RR+ GND TX– 9 RXI 12 TX+ 78Ω (NOTE 2) TXO RR– 5 RX– TRANSMIT PAIR CDS HBE NOTES: 1. T1 is a 1:1 pulse transformer, with an inductance of 30 to 100µH. 2. IN916 or equivalent for Ethernet, not required for Thin Ethernet. 3. 78Ω resistors not required if AUI cable not present. 4. Resistor value can be higher to reduce current consumption if AUI cable is not used. SD00289 Figure 1. Connection Diagram MAU COAX NE8392C COAX TRANSCEIVER INTERFACE I S O L A T I O N SERIAL NETWORK INTERFACE (OPTIONAL) (AUI CABLE) NETWORK INTERFACE CONTROLLER B U S DTE MAU = Medium Attachment Unit AUI Cable = Attachment Unit Interface Cable (not used in Thin Ethernet applications) SD00284 Figure 2. Interface Diagram for Ethernet/Thin Ethernet Local Area Network 1995 May 1 7 Philips Semiconductors Product specification Coaxial transceiver interface for Ethernet/Thin Ethernet NE8392C RXI 1 2 3 4 PHASE VIOLATION ALLOWED 5 6 VALID TIMING 7 8 9 10 11 tRD 90% RX+ tRF tRR 10% 1 2 3 4 5 6 7 8 9 10 11 tRON+2 tRON SD00277 Figure 3. Receiver Timing RXI tOS tRHI RX+ SD00279 Figure 4. Receiver End–of–Packet Timing tTST+2 100ns tTST tTOFF TX+ 1 2 3 4 5 6 7 tTON tTD 8 9 10 TXO 11 90% tTF 10% tTR 1 2 3 4 5 6 7 8 9 10 11 SD00278 Figure 5. Transmitter Timing RXI 0V –2V tCON tCOFF tCHI CD+ 1/FCD tCP SD00280 Figure 6. Collision Timing 1995 May 1 8 Philips Semiconductors Product specification Coaxial transceiver interface for Ethernet/Thin Ethernet NE8392C TX+ tHON tHW CD+ SD00281 Figure 7. Heartbeat Timing TX+ tJA tJR TXO CD+ SD00282 Figure 8. Jabber Timing 1995 May 1 9