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| FINAL AM7996 IEEE 802.3/Ethernet/Cheapernet Transceiver DISTINCTIVE CHARACTERISTICS s Compatible with Ethernet Version 2 and IEEE 802.3 10BASE-5 and10BASE-2 specifications s Pin-selectable SQE Test (heartbeat) option s Internal jabber controller prevents excessive transmission time s Noise rejection filter ensures that only valid data is transmitted onto the network s Collision detection on both transmit and receive data s Collision detect threshold levels adjustable for other networking applications GENERAL DESCRIPTION The AM7996 IEEE 802.3/Ethernet/Cheapernet Transceiver suppor ts Ethernet Version 2, IEEE 802.3 10BASE-5 and IEEE 802.3 10BASE-2--Cheapernet) transceiver applications. Transmit, receive, and collision detect functions at the coaxial media interface to the data terminal equipment (DTE) are all performed by this single device. In an IEEE 802.3 (10BASE-5)/Ethernet application, the AM7996 interfaces the coaxial (0.4 diameter) media to the DTE through an isolating pulse transformer and the 78 attachment unit interface (AUI) cable. In IEEE 802.3 10BASE-2--Cheapernet applications, the AM7996 typically resides inside the DTE with its signals to the DTE isolated and the coaxial (0.2 diameter) media directly connected to the DTE. Transceiver power and ground in both applications are isolated from that of the DTE. The AM7996's tap driver provides controlled skew and current drive for data signaling onto the media. The jabber controller prevents the node from transmitting excessively. While transmitting, collisions on the media are detected if one or more additional stations are transmitting. The AM7996 features an optional SQE Test function that provides a signal on the Cl pair at the end of every transmission. The SQE Test indicates the operational status of the Cl pair to the DTE. It can also serve as an acknowledgment to the node that packet transmission onto the coax was completed. BLOCK DIAGRAM Carrier Detect Circuit DI+ DI- Line Driver Control Logic Receive Data Amplifier Collision Detect Circuit Line Driver Control Logic Jabber Timer SQE Test Generator Input Buffer RXT Coaxial Media Interface AUI Interface CI+ CI- Transmit Squelch DO+ DO- SQE TEST Publication# 07506 Rev: E Amendment/0 Issue Date: May 1994 Input Buffer Transmit Data Amplifier Tap Driver TXT 07506E-1 1 AMD RELATED PRODUCTS Part No. Am79C98 Am79C100 Am79C981 Am79C987 Am79C940 Am79C90 Am79C900 Am79C960 Am79C961 Am79C965 Am79C970 Am79C974 Description Twisted Pair Ethernet Transceiver (TPEX) Twisted Pair Ethernet Transceiver Plus (TPEX+) Integrated Multiport Repeater PlusTM (IMR+TM) Hardware Implemented Management Information BaseTM (HIMIBTM) Media Access Controller for Ethernet (MACETM) CMOS Local Area Network Controller for Ethernet (C-LANCE) Integrated Local Area Communications ControllerTM (ILACCTM) PCnet-ISA Single-Chip Ethernet Controller (for ISA bus) PCnet-ISA+ Single-Chip Ethernet Controller (with Microsoft(R) Plug n' Play(R) Support) PCnet-32 Single-Chip 32-Bit Ethernet Controller (for 386DX, 486 and VL buses) PCnet-PCI Single-Chip Ethernet Controller (for PCI bus) PCnet-SCSI Combination Ethernet and SCSI Controller for PCI Systems CONNECTION DIAGRAMS DIP VCC1 CI+ CI- DI+ DI- VCREF SQE^TEST DO+ DO- VEE 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 VCC2 COLL OSC VCOL NC RXT NC TAP SHIELD VTX- TXT VTX+ DI+ DI- VCREF SQE^TEST DO+ 4 5 6 7 8 CI+ VCC1 VCC2 CI- PLCC COLL OSC VCOL NC RXT NC TAP SHIELD 3 2 1 20 19 18 17 16 15 14 9 10 11 12 13 DO- VEE VTX+ TXT VTX- 07506E-2 07506E-3 Notes: Pin 1 is marked for orientation. NC = No Connection 2 AM7996 ORDERING INFORMATION Standard Products AMD standard products are available in several packages and operating ranges. The order number (valid combination) is formed by a combination of the elements below. AM7996 D C B OPTIONAL PROCESSING Blank = Standard Processing B = Burn-In TR = Tape and Reel Packaging OPERATING CONDITIONS C = Commercial (0C to +70C) PACKAGE TYPE P = 20-Pin Plastic DIP (PD 020) D = 20-Pin Ceramic DIP (CD 020) J = 20-Pin Plastic Leaded Chip Carrier (PL 020) SPEED Not Applicable DEVICE NUMBER/DESCRIPTION AM7996 IEEE 802.3/Ethernet/Cheapernet Transceiver Valid Combinations AM7996 PC, PCB, DC, DCB, JC, JCTR Valid Combinations Valid combinations list configurations planned to be supported in volume for this device. Consult the local AMD sales office to confirm availability of specific valid combinations and to check on newly released combinations. AM7996 3 PIN DESCRIPTION Attachment Unit Interface (AUI) Dl+, Dl- Receive Line Output (Differential Outputs) This pair is intended to operate into terminated 78 transmission lines. Signals at RXT meeting bandwidth requirements and carrier sense levels are outputted at Dl . Signaling at Dl meets requirements of IEEE 802.3, Rev. D. Global Signals VCREF Timing Reference Set (Input) VCREF is a compensated voltage reference input with respect to VEE. When a resistor is connected between VCREF and V EE , then internal transmit and receive squelch timing, SQE oscillator frequency, and receive and SQE output drive levels are set. SQE frequency set is also determined by components connected between VCC1 and COLL OSC. Cl+, Cl- Collision Line Output (Differential Outputs) This pair is intended to operate into terminated 78 transmission lines. Signal Quality Error (SQE), detected at DO inputs (excessive transmissions) or RXT input (during a collision), outputs the 10 MHz internal oscillator signal to the AUI interface. For proper component values at COLL OSC, signaling at Cl meets requirements of IEEE 802.3, Rev. D. SQE TEST Signal Quality Error Test Enable (Input) The SQE Test function is enabled by connecting the SQE TEST pin to VEE and disabled by connecting to VCC. VTX+, VTX- Tap Node Driver Current Set (Inputs) A reference input for transmission level and external redundant jabber. Transmit level is set by an external resistor between VTX+ and VTX- (for an 80 mA peak level, R = 9.09 ). VTX- may be operated between VEE and VEE + 1 V. When the voltage at VTX- goes more positive than VEE + 2 V, TXT is disabled and an SQE message is output at the Cl pair. DO+, DO- Transmit Input (Differential Inputs) A pair of internally biased line receivers consisting of a squelch detect receiver with offset and noise filtering and a data receiver with zero offset for data signal processing. Signals meeting squelch requirements are waveshaped and output at TXT. TAP SHIELD Low-Noise Media Cable Return (Input) This input is the return for VCOL reference and the receive signal from the media. External connection is to a positive power supply. Coaxial Media Interface (TAP) RXT Media Signal Receiver Input (Input) RXT connects to the media through a 4:1 attenuator of 100 k total resistance (25 k and 75 k in series). Return for the attenuator is VCOL. RXT is an analog input with internal AC coupling for Manchester data signals and direct coupling for Carrier Detect and SQE average level detection. Signals at RXT meeting carrier squelch enable data to the Dl outputs. Data signals are AC coupled to Dl with a 150 ns time constant, high-pass filter. Signals meeting SQE levels enable COLL OSC frequency to Cl outputs. VCOL SQE Reference Voltage (Bias Supply) SQE sense voltage and RXT input amplifier reference. An internally set analog reference for SQE level and data signal set at -1.600 V nominal with a source resistance of 150 nominal. This reference should be filtered with respect to TAP SHIELD (see Applications section for adjusting threshold levels for other applications). COLL OSC SQE Timing Set (Input) Timing input for SQE oscillator. For a properly set input at VCREF, SQE oscillator period is set at 2.1RC. For a 10 MHz SQE oscillator frequency, R should be 1 k and C 47 pF, including interconnect and device capacitance. TXT Tap Node Driver (Input/Output) A controlled bandwidth current source and sense amplifier. This l/O port is to be connected to the media through an isolation network and a low-pass filter. Signals meeting DO squelch and jabber timing requirements are output at TXT as a controlled rise and fall time current pulse. When operated into a double terminated 50 transmission line, signaling meets IEEE 802.3, Rev. D recommendations for amplitude, pulse-width distortion, rise and fall times, and harmonic content. The sense amplifier monitors TXT faults and inhibits transmission. VCC1 Positive Logic Supply VCC2 SQE Timing Reference (Positive Supply Voltage) Timing reference return for SQE oscillator and analog signal ground. VEE Negative Logic Supply and IC Substrate 4 AM7996 FUNCTIONAL DESCRIPTION The AM7996 IEEE 802.3/Ethernet/Cheapernet Transceiver consists of four sections: 1) Transmit--receives signals from DTE and sends it to the coaxial medium; 2) Receive--obtains data from media and sends it to DTE; 3) Collision Detect--indicates to DTE any collision on the media; and 4) Jabber--guards medium from node transmissions that are excessive in length. data to the differential line driver within five bit times from the start of the packet. Received data is transmitted from the Dl pair through an isolation transformer to the AUI cable (Ethernet/ lEEE 802.3--10BASE-5). In IEEE 802.3 10BASE-2-- Cheapernet, the AUI cable is optional. Following the last transition of the packet, the Dl pair is held HIGH for two bit times and then decreases to idle level within twenty bit times. Transmit The AM7996 receives differential signals from the DTE (in the case of Am7990 family applications, from the Am7992 --serial interface adapter--SIA). For IEEE (10BASE-5)/Ethernet applications, this signal is received through the AUI cable and isolation transformer. In IEEE 802.3 10BASE-2--Cheapernet applications, the AUI cable is optional. Data is received through a noise rejection filter that rejects signals with pulse widths less than 7 ns (negative going), or with levels less than 175 mV peak. Only signals greater than -275 mV peak from the DTE are enabled. This minimizes false starts due to noise and ensures that no valid packets are missed. The AM7996's tap driver provides the driving capability to ensure adequate signal level at the end of the maximum length network segment (500 meters) under the worst-case number of connections (100 nodes). Required rise and fall times of data transmitted on the network are maintained by the AM7996 Tap Driver. The tap driver's output is connected to the media through external isolating diodes. To safeguard network integrity, the driver is disabled whenever power falls below the minimum operation voltage. During transmission, the AM7996 Jabber Controller monitors the duration that the transmit tap driver is active and disables the driver if the jabber time is exceeded. This prevents network tie-up due to a "babbling" transceiver. Once disabled, the driver is not reset until 400 ms after the DO pair is idle and there is no fault on TXT. During the disable time, an SQE signal is sent on the Cl pair to the DTE. When SQE TEST is tied to VEE, the AM7996 generates an SQE message at the end of every transmission. This signal is a self-test indication to the DTE that the media attachment unit (MAU) collision pair is operational. Collision Detect The AM7996 detects collisions on transmit if one or more additional stations are transmitting on the network. Received signals are compared against the collision threshold reference. If the level is more negative than the reference, an enable signal is generated to the Cl pair. The collision threshold can be modified by external components. The collision oscillator is a 10 MHz oscillator that drives the differential Cl pair to the DTE through an isolation transformer. This signal is gated to the Cl pair whenever there is a collision, the SQE Test is in progress, or the jabber controller is activated. The oscillator is also utilized in counting time for the jabber timer and SQE Test. The Cl output meets the drive requirements for the AUI interface. The output stays HIGH for two bit times at the end of the packet, decreasing to the idle level within twenty bit times. Jabber Function The AM7996 Jabber Timer monitors the activity on the DO pair and senses TXT faults. It inhibits transmission if the tap driver is active for longer than the jabber time (26 ms). An SQE message (10 MHz collision signal), is enabled on the Cl pair for the fault duration. After the fault is removed, the jabber timer counts the unjab time of 400 ms before it enables the driver. If desired, a redundant jabber function can be implemented externally, and the output driver disabled by removing the driver supply at VTX-.The AM7996 senses this condition and forces an SQE message on the Cl pair during the disable time. SQE Test An SQE Test will occur at the end of every transmission if the SQE TEST pin is tied to VEE. The SQE Test signal is a gated 10 MHz signal to the Cl pair. The SQE Test ensures that the twisted-pair assigned for collision notification to the DTE is intact and operational. The SQE Test starts eight bit times after the last transition of the transmitted signal and lasts for a duration of eight bit times. The SQE Test can be disabled by connecting the SQE TEST pin to VCC. Receive and Carrier Detect Signal is acquired from the tap through a highimpedance (100 k) resistive divider. A high inputimpedance (low capacitance, high bandwidth, low noise) DC-coupled input amplifier in the AM7996 receives the signal. The received signal passes through a high-pass filter to minimize inter-symbol distortion, and then through a data slicer. The AM7996 Carrier Detect compares received signals to a reference. Signals meeting carrier squelch requirements enable AM7996 5 AMD APPLICATIONS The AM7996 is compatible with Ethernet Version 2 and IEEE 802.3 10BASE5 and 10BASE2 applications. (See Figure 1). MAU Ethernet Local CPU Local Memory Am7990 LANCE DTE AUI Cable AM7996 Transceiver Tap Am7992B SIA Local Bus AUI - Attachment Unit Interface DTE - Data Terminal Equipment MAU - Media Access Unit Cheapernet Power Supply DTE Ethernet Coax Local CPU Local Memory Am7990 LANCE Am7992B SIA AM7996 Transceiver RG58 BNC "T" Local Bus Power Supply 07506E-4 Figure 1. Typical Ethernet Node Table 1. Transmit Mode Collision Detect Function Table Number of Transmitters <2 =2 >2 No No Yes May Yes Yes Table 3. Receive Mode Collision Detect Function Table Number of Transmitters <2 No No =2 Yes Yes >2 Yes Yes MAU Mode of Operation Transmitting Not Transmitting MAU Mode of Operation Transmitting Not Transmitting Table 2. IEEE 802.3 Recommended Transmit Mode Collision Detect Thresholds Threshold Voltage Level Table 4. IEEE 802.3 Recommended Receive Mode Collision Detect Thresholds Threshold Voltage Level IEEE 802.3 10BASE5, Ethernet 10BASE2, Cheapernet No Detect -1.492 V -1.404 V Must Detect - -1.782 V IEEE 802.3 10BASE5, Ethernet 10BASE2, Cheapernet No Detect -1.492 V -1.404 V Must Detect -1.629 V -1.581 V 6 AM7996 AMD Figure 2 is an external component diagram showing how to implement the transmit mode collision detect levels recommended by IEEE 802.3. Figure 3 on the following page shows how to implement the receive mode collision detect levels recommended by IEEE 802.3. Receive mode collision detect threshold levels of the AM7996 are implemented by adding R9, R10 and C4. For the values of the components shown in Figure 3, a nominal receive mode collision detect threshold of -1.5 V, for a -1.404 V to -1.581 V window, is achieved. PE64102/PE64107 (or equivalent) (75 H) R4 1.1 k C1 39 pF (Note 6) 2 CI+ 3 CI- 1:1 RCV 4 DI+ AM7996 R3 174 1:1 R1 40.2 1% R2 40.2 1% 1% 5 DI- 6 VCREF RXT 16 1% NC 15 (Note 5) 180 pF C3 1N4001 D3 R7 9 DO- 10 VEE TXT 12 R8 VTX+ 11 9.09 1% 9.09 1% CC (Note 1) (Note 2) D2 D1 COLL OSC 19 VCOL 18 NC 17 CL (Note 1) R6 24.9 k 1% R5 75 k C2 0.1 F Coax Connector 1:1 COLL 1 VCC1 VCC2 20 1% Tap 14 7 SQE^TEST Shield (Note 3) 8 DO+ VTX- 13 XMT 1N4150 -9 V Power (DTE) GND MAU Power Supply (Note 4) 07506E-5 Notes: 1. 2. 3. 4. CL is the effective load capacitance across R6; CC is the compensation capacitance (CC = 1/3 CL). D2 can be eliminated in Cheapernet (IEEE 802.3, 10BASE2) applications. Shown with SQE Test disabled. Discrete Power Supply or Hybrid-Hybrid DC-DC Converter Manufacturers include: Ethernet (IEEE 802.3, 10BASE5) Reliability: 2E12R9 Valor Electronics: PM1001 Cheapernet (IEEE 802.3, 10BASE2) Reliability Inc: 2VP5U9 Valor Electronics: PM7102 The capacitance of C3, AM7996 package, D3 and the printed circuit board should add up to 180 pF 20%. The capacitance of C1, AM7996 package and the printed circuit board should add up to 39 pF. Figure 2 used for production testing of all parameters that are tested. 5. 6. 7. Figure 2. AM7996 External Component Diagram for Transmit Mode Collision Detect AM7996 7 AMD PE64102/PE64107 (or equivalent) (75 H) R4 1.1 k C1 39 pF (Note 6) 2 CI+ 3 CI- 1:1 RCV 4 DI+ R3 174 1:1 R1 40.2 1% R2 40.2 1% 1% 5 DI- 6 COLL OSC 19 VCOL 18 R9 NC 17 499 AM7996 1% RXT 16 NC 15 (Note 7) CL (Note 1) R6 24.9 k 1% R5 75 k 1% C4 0.1 F C2 0.1 F Coax Connector 1:1 COLL 1 VCC1 VCC2 20 1% VCREF Tap 14 7 SQE^TEST Shield (Note 3) VTX- 13 8 DO+ 9 DO- 10 VEE TXT 12 VTX+ 11 R10 150 k 1% 180 pF C3 (Note 5) 1N4001 D3 R7 9.09 1% CC (Note 1) (Note 2) D2 D1 XMT 1N4150 9.09 1% -9 V Power (DTE) GND MAU Power Supply (Note 4) 07506E-6 Notes: 1. 2. 3. 4. CL is the effective load capacitance across R6; CC is the compensation capacitance (CC = 1/3 CL). D2 can be eliminated in Cheapernet (IEEE 802.3, 10BASE2) applications. Shown with SQE Test disabled. Discrete Power Supply or Hybrid-Hybrid DC-DC Converter Manufacturers include: Ethernet (IEEE 802.3, 10BASE5) Reliability: 2E12R9 Valor Electronics: PM1001 Cheapernet (IEEE 802.3, 10BASE2) Reliability Inc: 2VP5U9 Valor Electronics: PM7102 The capacitance of C3, AM7996 package, D3 and the printed circuit board should add up to 180 pF 20%. The capacitance of C1, AM7996 package and the printed circuit board should add up to 39 pF. R9, R10 and C4 are for Receive Mode Collision detection only. 5. 6. 7. Figure 3. AM7996 External Component Diagram with Collision Threshold Modified for Receive Mode Collision Detect 8 AM7996 AMD LAYOUT CONSIDERATIONS To protect the transceiver from the environment and to achieve optimum performance, the AM7996 is designed to be used with two sets of external components: the transmitter circuit consisting of components D1, D2, D3, R7, R8, and C3, and the receiver circuit consisting of components R5, R6, CL, and CC, (CL is a parasitic capacitance rather than a discrete component). These two circuits are shown in both Figure 2 and in Figure 3 respectively. The resistor tolerances for these circuits are specified as 1% for temperature stability. The only layout restriction for the transmitter circuit is that the longest current path from the TXT pin (Pin 12) to the coaxial cable's center conductor must be no longer than 4 inches. The layout of the receiver circuit, however, is critical. To minimize parasitic capacitance that can degrade the received signal, the external receiver circuit should be isolated from power and ground planes. There must be no power or ground plane under the area of the PC board that includes pins 15 through 20, R5, R6, and the connector for the coaxial cable. If a power or ground plane extends under this area, the receiver will not function properly due to excessive crosstalk and under- or overcompensation of the R5, R6 attenuator. Also, the RXT pin (Pin 16) should be as close to the coaxial cable connector as possible. Since there are no severe layout restrictions on the transmitter circuit, the layout can be simplified by omitting power and ground planes from the whole area on the right side of the AM7996 as shown in Figure 4-1. If the above layout rules are followed, the parasitic capacitance in parallel with R6 will be about 6 pF. This parasitic capacitance is shown in the schematics as CL (Note that CL is a parasitic capacitance. Do not add a discrete capacitor in parallel with R6). The capacitor labeled CC in the schematics is the total capacitance in parallel with R5 including parasitic capacitance. The parasitic component of CC will be about 1 pF. For optimum performance, the ratio of CL to CC should be the same as the ration of R5 to R6, which is 3 to 1. This means that an additional 1 pF of capacitance must be added in parallel with R5. This additional capacitance can easily be added by building a parallel-plate capacitor for PC traces right under resistor R5. This capacitor can consist of a 0.200 in. by 0.200 in. square of conductor on each side of the board as shown in Figure 4-2 (These dimensions assume that the PC board is made from 0.060 in. thick G-10 material). The top plate of the capacitor should be connected to one lead of R5, and the bottom plate should be connected to the other lead. Figure 4-3 shows an example of this suggested layout for a four layer printed circuit board. Note that the component labeling used in Figure 4-3 is not intended to correspond with the component labeling used in Figure 2 and Figure 3. R5 Component Side Circuit Side 0.200 in x 0.200 in two planes 07506E-8 20 RXT AM7996 TXT 11 Area with no power or ground plane 07506E-7 R5, R6, R4 C1, C2 D1, D2, D3 R7, R8 C3 Coax Connector Figure 4-2. Figure 4-1. AM7996 9 AMD ABSOLUTE MAXIMUM RATINGS Storage Temperature . . . . . . . . . . . -65C to +150C Ambient Temperature Under Bias . . . . . . . . . . . . . . . . . . . . . . 0C to +70C Supply Voltages (VEE, VTX-) . . . . . -12.0 V to +0.5 V DC Input Voltage (D0+, D0-) . . . . -12.0 V to +0.5 V DC Input Voltage (RXT) . . . . . . . . . . . -6 V to +0.5 V Stresses above those listed under Absolute Maximum Ratings may cause permanent device failure. Functionality at or above these limits is not implied Exposure to absolute maximum ratings for extended periods may affect device reliability. OPERATING RANGES Commercial (C) Devices Ambient Temperature (TA) . . . . . . . 0C to +70C Supply Voltage (VEE) . . . . . . . . . . -8.1 V to -9.9 V Operating ranges define those limits between which the functionality of the device is guaranteed AM7996 11 AMD DC CHARACTERISTICS over operating ranges unless otherwise specified Parameter Symbol VTXTH VTXTL VTXT VICM VIDC ITXTL IILD IIHD RIDF RICM VOD VCMT VODI VOD OFF VCAT VCOT IRXT IOD OFF Global Supply Current-Non-Transmitting IEE Supply Current-Transmitting RLX = 25 (Note 4) -88 -128 -105 -155 mA Input Current (DO+, DO-) VEE = Max Parameter Description Transmit Output HIGH Voltage (Note 1) Transmit Output LOW Voltage (Note 1) Transmit Average DC Voltage with 50% Duty-Cycle into DO+, DO- (Note 1) DO+, DO- Common Mode Bias Voltage Differential Input Squelch Threshold (DO+, DO-) (Note 9) Transmit Current (Note 9) VTXT = -5.5 V VIN = VEE Max VIN = 0 VIN = 0 to VEE 6 1.5 +550 -550 -1.0 8 2 +670 -670 -2.0 5 -20 -400 0 -500 +850 -850 -3.0 20 +20 -600 -1700 +0.5 +0.5 Test Conditions (Note 10) RLX = 25 RLX = 25 RLX = 25 IIN = 0 Commercial Min Typ Max 0 -1.625 -0.925 VEE + 1.2 -175 -65 -0.05 -2.0 -1.0 VEE + 1.5 -225 -0.425 -2.2 -1.1 VEE + 1.8 -275 -88 -2.0 2.5 mA k k Unit V V V Transmit Signals V mV mA Differential Input Resistance (DO+, DO-) Common-Mode Input Resistance (DO+, DO-) VIN = 0 to VEE Differential Output Voltage (DI+, DI-; CI+, CI-) Common-Mode Output (DI+, DI-; CI+, CI-) Differential Output Voltage Imbalance (DI+, DI-; CI+, CI-) ||VOD| - |VOD|| (Note 6) Differential Output Idle Voltage (DI+, DI-; CI+, CI-) Carrier Sense Threshold Collision Sense Threshold (Note 5) RXT Input Bias Current Differential Output Idle Current (DI+, DI-; CI+, CI-) VIN = 1 V to -2.5 V; VEE = Max RL = 0 VOD+ VOD- RL = 78 RL = 78 RL = 78 , VEE = Max VIN = 5 MHz Preamble Receive/Collision Signals RL = 78 mV V mV mV mV mV A mA -1515 -1600 -0.5 -0.5 0 0 CAPACITANCE* (TA = 25C; VEE = 0; Pins 15, 17--No Connections) Parameter Symbol CRXT Parameter Description RXT Input Capacitance Test Conditions Ceramic DIP Plastic DIP/PLCC Min Typ 1.7 1.1 Max Unit pF Notes: See notes following Switching Characteristics section. *Parameters are not "Tested." 12 AM7996 AMD SWITCHING CHARACTERISTICS over operating ranges unless otherwise specified No Parameter Symbol Parameter Description Test Conditions Commercial Min Typ Max Unit Receiver Specification 1 2 3 4 5 7 8 9 10 11 12 13 14 tPWREJ tPWTON tPWSON tPWOFF tTON tTSD tTXTR tTXTF tDRF tSKEW tJCT tJRT tJREC DO Input Pulse Width to Reject (DO VIDC, Max) DO Input Pulse Width to Turn On (DO > VIDC, Max) DO Input Pulse Width to Stay On (DO VIDC, Max) DO Input Pulse Width to Turn Off (DO VIDC, Max) Transmit Driver Turn-On Delay Transmit Static Delay (Zero Crossing to 50% Point to Coax) Transmit Driver Rise Time Transmit Driver Fall Time Difference in Driver Rise and Fall Times |tTXTR-tTXTF| Output Driver Skew--Transmit Data Symmetry Jabber Control Time Jabber Reset Time Jabber Recovery Time (Note 1) (Note 1) (Note 1) (Note 1) (Note 1) (Note 1) (Notes 1, 7) (Notes 1, 7) (Notes 1, 7) (Note 1) (Note 1) (Note 1) (Note 1) -2.0 20 340 26 419 20 20 30 25 25 160 200 50 30 30 1.0 +2.0 35 500 1.0 20 15 15 105 7 ns ns ns ns ns ns ns ns ns ns ms ms s Receive/Collision Specification 15 16 17 tRON tROFF tRSD Receiver Turn-On Delay Receiver Turn-Off Delay Receiver Static Delay Vtap > VCAT Max Vtap < VCAT Min 50% Point at RXT at Zero Crossing at DI Outputs -2 20%-80%, RL = 78 80%-20%, RL = 78 Vtap > VCOT Max Vtap < VCOT Min 35 35 (Note 8) FCI = 10.0 MHz FCI = 10.0 MHz 8.5 600 600 800 50 50 10.0 250 500 1000 ns ns 50 +2 7 7 900 2000 70.5 70.5 11.5 1000 1000 ns % ns ns ns ns ns ns MHz ns ns 18 19 20 21 22 23 24 25 26 27 tRS tRR tRF tCON tCOFF tCL tCH fCI tSTD tSTL Receive Data Symmetry DI and CI Rise Time DI and CI Fall Time CI Turn-On Delay CI Turn-Off Delay CI LOW Time CI HIGH Time Collision Frequency SQE Test Delay Time SQE Test Length AM7996 13 AMD Notes: 1. Parameters are measured at coax tap. In production test, parameters are measured across at 25 load equivalent to the coax tap. 2. For conditions shown as Min or Max, use the appropriate value specified under Operating Range for the applicable device type. 3. Typical values are at VEE = -9.0 V, 25C ambient. 4. VTX- wired to VEE. 5. This threshold can be modified externally (see Figure 3). 6. Parameter not tested. 7. Tested on a 5 Mbps preamble (continuous 1010 pattern) measured between 20% and 80% points, test limits correlated to 10% and 90% data sheet limits shown. 8. Determined by Am7966 External Component Diagrams values for R4 and C1. 9. In production test, input signal applied thru transformer to DO inputs. 10. Figure 2 used for production testing of all parameters. *Notes listed correspond to the respective references made in DC Characteristics and Switching Characteristics tables. 14 AM7996 AMD KEY TO SWITCHING WAVEFORMS WAVEFORM INPUTS Must be Steady May Change from H to L May Change from L to H Don't Care, Any Change Permitted Does Not Apply OUTPUTS Will be Steady Will be Changing from H to L Will be Changing from L to H Changing, State Unknown Center Line is HighImpedance "Off" State KS000010 SWITCHING TEST CIRCUIT + 1/3 PE64102/PE64107 (or equivalent) DUT - 75 H RL 78 07506E-12 A. AUI Transmit (DI+, DI-,; CI+, CI-) RLX = 25 07506E-13 B. Test Load (TXT) AM7996 15 AMD SWITCHING WAVEFORMS DO VIDC 2 90% COAX TAP (Transmit) 10% VTXTL 8 5 7 7 9 0V 50% 0V 07506E-14 Transmit Function NEAR END 0V VCATmax COAX TAP (Receive) 50% VCATmin VOD DI 0V -VOD 15 17 17 17 17 16 07506E-15 Receiver Function 16 AM7996 AMD SWITCHING WAVEFORMS DO 0V 0V COAX TAP (Transmit) VTXTL VOD CI 0V -VOD 26 27 07506E-16 SQE Test* *SQE^TEST pin connected to VEE 50% DO 0V 0V COAX TAP (Transmit) VTXTL 50% CI 0V 12 13 07506E-17 Jabber Function AM7996 17 AMD SWITCHING WAVEFORMS 80% DI CI VOD 0V 20% -VOD 19 20 VOD CI 0V -VOD 23 24 1/fCI 07506E-18 DI/CI Parameters 0V COAX TAP VCOTMAX -2 V VCOTMIN 350 mV CI VOD 0V -VOD 21 22 07506E-19 Collision Detect Timing Note: This signal is used for test purposes. It represents the average value of the signal that might be seen on the coax tap when a collision occurs. 18 AM7996 |
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