FINAL Am7996 IEEE 802.3/Ethernet/Cheapernet Transceiver DISTINCTIVE CHARACTERISTICS ■ Compatible with Ethernet Version 2 and IEEE 802.3 10BASE-5 and10BASE-2 specifications ■ Pin-selectable SQE Test (heartbeat) option ■ Internal jabber controller prevents excessive transmission time ■ Noise rejection filter ensures that only valid data is transmitted onto the network ■ Collision detection on both transmit and receive data ■ 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 Ω 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+ Line Driver Control Logic CI+ Input Buffer RXT Collision Detect Circuit Line Driver Control Logic CI– Coaxial Media Interface AUI Interface DI– Receive Data Amplifier Jabber Timer SQE Test Generator 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. Description Am79C98 Twisted Pair Ethernet Transceiver (TPEX) Am79C100 Twisted Pair Ethernet Transceiver Plus (TPEX+) Am79C981 Integrated Multiport Repeater Plus (IMR+) Am79C987 Hardware Implemented Management Information Base (HIMIB) Am79C940 Media Access Controller for Ethernet (MACE) Am79C90 CMOS Local Area Network Controller for Ethernet (C-LANCE) Am79C900 Integrated Local Area Communications Controller (ILACC) Am79C960 PCnet-ISA Single-Chip Ethernet Controller (for ISA bus) Am79C961 PCnet-ISA+ Single-Chip Ethernet Controller (with Microsoft Plug n’ Play Support) Am79C965 PCnet-32 Single-Chip 32-Bit Ethernet Controller (for 386DX, 486 and VL buses) Am79C970 PCnet-PCI Single-Chip Ethernet Controller (for PCI bus) Am79C974 PCnet-SCSI Combination Ethernet and SCSI Controller for PCI Systems CONNECTION DIAGRAMS 20 VCC2 CI+ 2 19 COLL OSC CI– 3 18 VCOL DI+ 4 17 NC DI– 5 16 RXT VCREF 6 15 NC SQE^TEST 7 14 TAP SHIELD DO+ 8 13 VTX– DO– 9 12 TXT 10 11 VTX+ SQE^TEST DO+ 07506E-2 3 2 1 20 19 18 17 16 15 14 9 10 11 12 13 VCOL NC RXT NC TAP SHIELD 07506E-3 Notes: Pin 1 is marked for orientation. NC = No Connection 2 4 5 6 7 8 DO– VEE VTX+ VEE DI+ DI– VCREF TXT VTX– 1 CI– VCC1 COLL OSC PLCC CI+ VCC1 VCC2 DIP 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 (0°C to +70°C) 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 Valid Combinations AM7996 PC, PCB, DC, DCB, JC, JCTR 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– Global Signals VCREF Receive Line Output (Differential Outputs) This pair is intended to operate into terminated 78 Ω 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. Cl+, Cl– Collision Line Output (Differential Outputs) This pair is intended to operate into terminated 78 Ω 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. 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. Coaxial Media Interface (TAP) RXT Media Signal Receiver Input (Input) RXT connects to the media through a 4:1 attenuator of 100 kΩ total resistance (25 kΩ and 75 kΩ 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. 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 Ω 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. 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. 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 Ω). 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. 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. 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 Ω 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 kΩ and C 47 pF, including interconnect and device capacitance. 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. 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. Receive and Carrier Detect Signal is acquired from the tap through a highimpedance (100 kΩ) 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 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. 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. Am7996 5 AMD APPLICATIONS The Am7996 is compatible with Ethernet Version 2 and IEEE 802.3 10BASE5 and 10BASE2 applications. (See Figure 1). MAU Local CPU AUI Cable DTE Ethernet Local Memory Am7990 LANCE Tap Am7996 Transceiver Am7992B SIA Power Supply Local Bus AUI - Attachment Unit Interface DTE - Data Terminal Equipment MAU - Media Access Unit Cheapernet DTE Ethernet Coax Local CPU Local Memory Am7990 LANCE Am7996 Transceiver Am7992B SIA RG58 BNC "T" Power Supply Local Bus 07506E-4 Figure 1. Typical Ethernet Node Table 1. Transmit Mode Collision Detect Function Table MAU Mode of Operation Table 3. Number of Transmitters <2 =2 >2 Receive Mode Collision Detect Function Table MAU Mode of Operation <2 =2 >2 Transmitting No Yes Yes Transmitting No Yes Yes Not Transmitting No May Yes Not Transmitting No Yes Yes Table 2. IEEE 802.3 Recommended Transmit Mode Collision Detect Thresholds Table 4. IEEE 802.3 Recommended Receive Mode Collision Detect Thresholds Threshold Voltage Level IEEE 802.3 No Detect Threshold Voltage Level Must Detect 10BASE5, Ethernet –1.492 V – 10BASE2, Cheapernet –1.404 V –1.782 V 6 Number of Transmitters IEEE 802.3 No Detect Must Detect 10BASE5, Ethernet –1.492 V –1.629 V 10BASE2, Cheapernet –1.404 V –1.581 V Am7996 AMD 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. 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 PE64102/PE64107 (or equivalent) (75 µH) 1:1 1 VCC2 20 VCC1 1% R4 1.1 kΩ C1 39 pF C2 0.1 µF Coax Connector (Note 6) COLL 1:1 2 CI+ COLL OSC 19 3 CI– VCOL 18 4 DI+ NC 17 CL (Note 1) Am7996 RCV R3 174 Ω 1% 1:1 R5 75 kΩ RXT 16 1% 6 NC 15 VCREF (Note 5) Tap 14 7 SQE^TEST Shield (Note 3) 8 DO+ VTX- 13 R1 40.2 Ω 1% R2 40.2 Ω 1% XMT 5 DI– R6 24.9 kΩ 1% 180 pF C3 1N4001 D3 R7 9 DO– TXT 12 10 VEE VTX+ 11 R8 9.09 Ω 1% CC (Note 1) (Note 2) D2 9.09 Ω 1% D1 1N4150 –9 V Power (DTE) GND MAU Power Supply (Note 4) 07506E-5 Notes: 1. CL is the effective load capacitance across R6; CC is the compensation capacitance (CC = 1/3 CL). 2. D2 can be eliminated in Cheapernet (IEEE 802.3, 10BASE2) applications. 3. Shown with SQE Test disabled. 4. 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 5. The capacitance of C3, Am7996 package, D3 and the printed circuit board should add up to 180 pF ± 20%. 6. The capacitance of C1, Am7996 package and the printed circuit board should add up to 39 pF. 7. Figure 2 used for production testing of all parameters that are tested. Figure 2. Am7996 External Component Diagram for Transmit Mode Collision Detect Am7996 7 AMD PE64102/PE64107 (or equivalent) (75 µH) 1:1 1 VCC2 20 VCC1 1% R4 1.1 kΩ C1 39 pF C2 0.1 µF Coax Connector (Note 6) COLL 1:1 COLL OSC 19 3 CI– VCOL 18 4 DI+ RCV R3 174 Ω 1% 1:1 5 DI– 6 C4 0.1 µF R9 NC 17 499 Ω Am7996 1% RXT 16 (Note 7) CL (Note 1) R6 24.9 kΩ 1% 180 pF C3 1N4001 D3 R7 (Note 5) 9 DO– TXT 12 10 VEE VTX+ 11 9.09 Ω 1% R5 75 kΩ 1% R10 150 kΩ 1% NC 15 VCREF Tap 14 7 SQE^TEST Shield (Note 3) VTX– 13 8 DO+ R1 40.2 Ω 1% R2 40.2 Ω 1% XMT 2 CI+ CC (Note 1) (Note 2) D2 9.09 Ω 1% D1 1N4150 –9 V Power (DTE) GND MAU Power Supply (Note 4) 07506E-6 Notes: 1. CL is the effective load capacitance across R6; CC is the compensation capacitance (CC = 1/3 CL). 2. D2 can be eliminated in Cheapernet (IEEE 802.3, 10BASE2) applications. 3. Shown with SQE Test disabled. 4. 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 5. The capacitance of C3, Am7996 package, D3 and the printed circuit board should add up to 180 pF ± 20%. 6. The capacitance of C1, Am7996 package and the printed circuit board should add up to 39 pF. 7. R9, R10 and C4 are for Receive Mode Collision detection only. 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. 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. 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. R5 Circuit Side Component Side 20 RXT 0.200 in x 0.200 in two planes R5, R6, R4 C1, C2 07506E-8 Am7996 TXT D1, D2, D3 R7, R8 C3 Figure 4-2. Coax Connector 11 Area with no power or ground plane 07506E-7 Figure 4-1. Am7996 9 AMD ABSOLUTE MAXIMUM RATINGS OPERATING RANGES Storage Temperature . . . . . . . . . . . –65°C to +150°C Ambient Temperature Under Bias . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C 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 Commercial (C) Devices Ambient Temperature (TA) . . . . . . . 0°C to +70°C Supply Voltage (VEE) . . . . . . . . . . –8.1 V to –9.9 V Operating ranges define those limits between which the functionality of the device is guaranteed 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. Am7996 11 AMD DC CHARACTERISTICS over operating ranges unless otherwise specified Parameter Symbol Parameter Description Test Conditions (Note 10) Commercial Min Typ Max Unit Transmit Signals VTXTH Transmit Output HIGH Voltage (Note 1) RLX = 25 Ω 0 –0.05 –0.425 V VTXTL Transmit Output LOW Voltage (Note 1) RLX = 25 Ω –1.625 –2.0 –2.2 V VTXT Transmit Average DC Voltage with 50% Duty-Cycle into DO+, DO– (Note 1) RLX = 25 Ω –0.925 –1.0 –1.1 V VICM DO+, DO– Common Mode Bias Voltage IIN = 0 VEE + 1.2 VEE + 1.5 VEE + 1.8 V VIDC Differential Input Squelch Threshold (DO+, DO–) (Note 9) –175 –225 –275 mV ITXTL Transmit Current (Note 9) –88 mA VTXT = –5.5 V IILD IIHD Input Current (DO+, DO–) VEE = Max –65 VIN = VEE Max –2.0 VIN = 0 2.5 RIDF Differential Input Resistance (DO+, DO–) RICM Common-Mode Input Resistance (DO+, DO–) VIN = 0 to VEE VIN = 0 to VEE mA 6 8 kΩ 1.5 2 kΩ VOD+ VOD– +550 –550 +670 –670 +850 –850 mV –1.0 –2.0 –3.0 V 5 20 mV Receive/Collision Signals VOD Differential Output Voltage (DI+, DI–; CI+, CI–) RL = 78 Ω VCMT Common-Mode Output (DI+, DI–; CI+, CI–) RL = 78 Ω VODI Differential Output Voltage Imbalance (DI+, DI–; CI+, CI–) ||VOD| – |VOD|| (Note 6) RL = 78 Ω Differential Output Idle Voltage (DI+, DI–; CI+, CI–) RL = 78 Ω, VEE = Max –20 0 +20 mV VCAT Carrier Sense Threshold VIN = 5 MHz Preamble –400 –500 –600 mV VCOT Collision Sense Threshold (Note 5) –1515 –1600 –1700 mV IRXT RXT Input Bias Current VIN = 1 V to –2.5 V; VEE = Max –0.5 0 +0.5 µA Differential Output Idle Current (DI+, DI–; CI+, CI–) RL = 0 –0.5 0 +0.5 mA –88 –105 –128 –155 Typ Max VOD OFF IOD OFF Global Supply Current–Non-Transmitting IEE Supply Current–Transmitting RLX = 25 Ω (Note 4) mA CAPACITANCE* (TA = 25°C; VEE = 0; Pins 15, 17—No Connections) Parameter Symbol CRXT Parameter Description RXT Input Capacitance Test Conditions 1.7 Plastic DIP/PLCC 1.1 Notes: See notes following Switching Characteristics section. *Parameters are not “Tested.” 12 Min Ceramic DIP Am7996 Unit pF AMD SWITCHING CHARACTERISTICS over operating ranges unless otherwise specified No Parameter Symbol Test Conditions Commercial Min Typ Max Unit DO± Input Pulse Width to Reject (DO± ≥ VIDC, Max) (Note 1) 15 ns DO± Input Pulse Width to Turn On (DO± > VIDC, Max) (Note 1) DO± Input Pulse Width to Stay On (DO± ≥ VIDC, Max) (Note 1) DO± Input Pulse Width to Turn Off (DO± ≥ VIDC, Max) (Note 1) Parameter Description Receiver Specification 1 2 3 4 tPWREJ tPWTON tPWSON tPWOFF 5 tTON Transmit Driver Turn-On Delay (Note 1) 7 tTSD Transmit Static Delay (Zero Crossing to 50% Point to Coax) (Note 1) 20 7 15 ns 105 160 ns ns 200 ns 30 50 ns 8 tTXTR Transmit Driver Rise Time (Notes 1, 7) 20 25 30 ns 9 tTXTF Transmit Driver Fall Time (Notes 1, 7) 20 25 30 ns 10 tDRF Difference in Driver Rise and Fall Times |tTXTR–tTXTF| (Notes 1, 7) 1.0 ns +2.0 ns 11 tSKEW Output Driver Skew—Transmit Data Symmetry (Note 1) –2.0 12 tJCT Jabber Control Time (Note 1) 20 26 35 ms 13 tJRT Jabber Reset Time (Note 1) 340 419 500 ms 14 tJREC Jabber Recovery Time (Note 1) 1.0 µs 500 ns Receive/Collision Specification 15 tRON Receiver Turn-On Delay Vtap > VCAT Max 16 tROFF Receiver Turn-Off Delay Vtap < VCAT Min 1000 ns 17 tRSD Receiver Static Delay 50% Point at RXT at Zero Crossing at DI± Outputs 50 ns +2 % 20%–80%, RL = 78 Ω 7 ns 80%–20%, RL = 78 Ω 7 ns 18 tRS Receive Data Symmetry 19 tRR DI± and CI± Rise Time 20 tRF 250 –2 DI± and CI± Fall Time 21 tCON CI± Turn-On Delay Vtap > VCOT Max 900 ns 22 tCOFF CI± Turn-Off Delay Vtap < VCOT Min 2000 ns 23 tCL CI± LOW Time 35 50 70.5 ns 24 tCH CI± HIGH Time 35 50 70.5 ns 25 fCI Collision Frequency (Note 8) 8.5 10.0 11.5 MHz 26 tSTD SQE Test Delay Time FCI = 10.0 MHz 600 1000 ns 27 tSTL SQE Test Length FCI = 10.0 MHz 600 1000 ns Am7996 800 13 AMD Notes: 1. Parameters are measured at coax tap. In production test, parameters are measured across at 25 Ω 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, 25°C 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 OUTPUTS Must be Steady Will be Steady May Change from H to L Will be Changing from H to L May Change from L to H Will be Changing from L to H Don’t Care, Any Change Permitted Changing, State Unknown Does Not Apply Center Line is HighImpedance “Off” State KS000010 SWITCHING TEST CIRCUIT + 1/3 PE64102/PE64107 (or equivalent) DUT RL – 78 Ω 75 µH 07506E-12 A. AUI Transmit (DI+, DI–,; CI+, CI–) RLX = 25 Ω 07506E-13 B. Test Load (TXT) Am7996 15 AMD SWITCHING WAVEFORMS 0V DO± VIDC 2 90% 0V COAX TAP 50% 10% (Transmit) VTXTL 8 9 5 7 7 07506E-14 Transmit Function NEAR END 0V VCATmax VCATmin 50% COAX TAP (Receive) VOD 0V DI± –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% 0V DO± 0V COAX TAP (Transmit) VTXTL 50% CI± 12 0V 13 07506E-17 Jabber Function Am7996 17 AMD SWITCHING WAVEFORMS VOD 80% DI± CI± 0V 20% –VOD 19 20 VOD CI± 0V –VOD 24 23 1/fCI 07506E-18 DI±/CI± Parameters 0V COAX TAP VCOTMAX VCOTMIN –2 V 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