November 1998 ML4658 10BASE-T Transceiver GENERAL DESCRIPTION FEATURES The ML4658 10BASE-T Transceiver is a single chip cable line driver/receiver that provides all of the functionality required to implement both an internal and external IEEE 802.3 10BASE-T MAU. This part offers a standard IEEE 802.3 AU interface that allows it to directly connect to industry standard manchester encoder/decoder chips or to an AUI cable. ■ The ML4658 requires a minimal number of external components, and is compliant to the IEEE 802.3 10BASE-T standard. The differential current driven transmitter offers superior performance because of its highly symetrical switching. This results in low RFI noise and low jitter. ■ ■ ■ ■ ■ ■ ■ The Transceiver easily interfaces to 100Ω unshielded twisted pair cable, 150Ω shielded twisted pair cable, or a range of other characteristic impedances by simply changing one external resistor. Jabber, Link Test, and SQE Test are fully integrated onto the chip with enable/disable options. A polarity detection status pin, which can drive an LED, is provided for receive data, and the ML4658 offers automatic polarity correction. ■ ■ Complete implementation of IEEE 802.3 10BASE-T Medium Attachment Unit (MAU) Incorporates an AU interface for use in an external MAU or internal MAU Single 5V supply ±10% No crystal or clock input Current Driven Output for low RFI noise and low jitter Capable of driving 100Ω unshielded twisted pair cable or 150Ω shielded twisted pair cable Polarity detect status pin capable of driving an LED Automatic Polarity Correction On-chip Jabber logic, Link Test, and SQE test with enable/disable option Provides six network status LED ouput pins BLOCK DIAGRAM 5V RTSET SQEN/LTD/JABD Tx+ Tx– LINK PULSE AUI RECEIVER TxTP+ PRE-EQUALIZED TRANSMIT DRIVER TRANSMIT SQUELCH TxTP– TxCAP0 TxCAP1 JABBER SQE RECEIVE SQUELCH COL+ COL– AUI DRIVER Rx+ Rx– AUI DRIVER RxTP+ 10MHz GATED OSCILLATOR LOOPBACK MUX LINE RECEIVER RxTP– Tx Rx LINK TEST RECEIVE LOGIC AUTOMATIC POLARITY CORRECTION BIAS LED DRIVERS GND VCC (5V) CLSN JAB RCV XMT LTF POLRD RRSET 5V 1 ML4658 PIN CONFIGURATION COL+ CLSN JAB BIAS 4 3 2 1 28 27 26 RxTP+ COL– ML4658 28-Pin PCC SQEN/LTD/JABD ML4658 24-Pin DIP 24 JAB COL+ 2 23 BIAS COL– 3 22 RxTP+ SQEN/LTD/JABD 4 21 RxTP– NC 5 25 RxTP– Rx+ 5 20 LTF Rx+ 6 24 LTF Rx– 7 23 NC VCC 8 22 TxCAP0 VCC 9 21 TxCAP1 Tx+ 10 20 GND Tx– 11 19 GND 18 TxCAP1 Tx+ 8 17 GND Tx– 9 16 TxTP+ RTSET 10 15 TxTP– RRSET 11 14 RCV POLRD 12 13 XMT 12 13 14 15 16 17 18 TOP VIEW TxTP+ 7 RCV VCC XMT TxCAP0 POLRD 19 RRSET 6 Rx– TxTP– 1 RTSET CLSN TOP VIEW PIN DESCRIPTION (DIP) PIN# NAME FUNCTION 1 CLSN Indicates that a collision is taking place. Active low LED driver, open collector. Event is extended 100ms for visibility. 2 3 COL+ COL– Gated 10MHz signal used to indicate a collision, SQE test, or jabber. Balanced differential line driver outputs that meet AU interface specifications. AC or DC coupled. 4 SQEN/LTD/ SQE Test Enable, Link Test Disabled, Jabber Disabled. This input uses four voltage levels to JABD configure the chip as shown in Table 1. Table 1. SQEN/LTD/JABD Pin Configuration Pin 0V (GND) 1.2V BIAS 5V (VCC) SQE Test Disabled Disabled Enabled Enabled Link Test Enabled Disabled Disabled Enabled Jabber Enabled Disabled Enabled Enabled When link test is disabled, no link pulses are transmitted, and the transmitter and receiver will not be disabled as a result of a loss of receive link pulses. When Jabber is disabled the transmitter can transmit continuously without interruption, and the collision oscillator will not be activated. 5 6 Rx+ Rx– Manchester encoded receive data output to the local device. Balanced differential line driver outputs that meet AU interface specifications. AC or DC coupled. 7 VCC 5 Volt power input. 8 9 Tx+ Tx– Balanced differential line receiver inputs that meet AU interface specifications. These inputs may be AC or DC coupled. When AC coupled, the BIAS pin is used to set the common mode voltage. Signals meeting the transmitter squelch input requirements are pre-equalized and output on TxTP+ and TxTP–. 10 RTSET When using 100Ω unshielded twisted pair, a 220Ω resistor is tied between this pin and VCC. When using 150Ω shielded twisted pair, a 330Ω resistor is tied between this pin and VCC. 11 RRSET A 1% 61.9KΩ resistor tied from this pin to VCC is used for internal biasing. 2 ML4658 PIN DESCRIPTION (DIP) PIN# NAME (Continued) FUNCTION 12 POLRD Receive Polarity status. Active low LED Driver, open collector output. Indicates the polarity of the receive twisted pair regardless of auto polarity correction. When this pin is high, the receive polarity is correct, and when this pin is low the receive polarity is reversed. 13 XMT Indicates that transmission is taking place on the TxTP+, TxTP– pair. Active low LED driver, open collector. It is extended 100ms for visibility. 14 RCV Indicates that the transceiver has unsquelched and is receiving data from the twisted pair. Active low LED driver, open collector. It is extended 100ms for visibility. 15 TxTP– 16 TxTP+ Pre-equalized differential balanced current driven output. These ouputs are connected to a balanced transmit output filter which drives the twisted pair cable through pulse transformers. The output current is set with an external resistor connected to RTSET allowing the chip to drive 100Ω unshielded twisted pair, 150Ω shielded twisted pair cables or a range of other characteristic impedances. 17 GND Ground reference. 18 TxCAP1 19 TxCAP0 An external capacitor of 330pF is tied between these two pins to set the pulse width for the preequalization on the transmitter. If these two pins are shorted together, no pre-equalization occurs. 20 LTF Link Test Fail. Active high. Normally this pin is low, indicating that the link is operational. If the link goes down resulting from the absence of link pulses or frames being received, the chip will go into the Link Test Fail state and bring LTF high. In the Link Test Fail state, both the transmitter and receiver are disabled, however link pulses are still sent. A station that only has access to the AUI can detect a Link Test Fail by the absence of loopback. This pin is low when the Link Test is disabled. Open collector LED output. 21 RxTP– Twisted Pair receive data input. When this signal exceeds the receive squelch requirements the receive data is buffered and sent to the Rx± outputs. 22 RxTP+ 23 BIAS Bias voltage, output. Used to bias the receive twisted pair inputs as well as the Tx± inputs when they are AC coupled. 24 JAB Open collector TTL output capable of driving an LED. When in the Jabber state, this pin will be low and the transmitter will be disabled. In the Jabber “OK” state this pin will be high. 3 ML4658 ABSOLUTE MAXIMUM RATINGS (Note 1) Power Supply Voltage Range VCC ............................................................................... –0.3 to 6V Input Voltage Range Digital Inputs (SQEN, LTD) ........................ –0.3 to V CC Tx+, Tx–, RxTP+, RxTP– ............................ –0.3 to VCC Input Current RRSET, RTSET, JAB, CLSN, XMT, RCV, LTF .......... 60mA Output Current TxTP+, TxTP– ...................................................... 80mA Storage Temperature ................................ –65°C to 150°C Lead Temperature (Soldering 10 sec.) ..................... 260°C OPERATING CONDITIONS Supply Voltage (VCC) ......................................... 5V ±10% LED on Current ....................................................... 10mA RRSET ......................................................... 61.9KΩ ±1% RTSET ............................................................ 220Ω ±1% TxCAP .................................................................... 330pF ELECTRICAL CHARACTERISTICS Unless otherwise specified, TA = 0°C to 70°C (Note 3), VCC = 5V ±10% (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS Power Supply Current ICC (Note 4) VCC = 5V 140 mA LED Drivers: VOL RL = 510Ω (Note 5) 0.8 V Transmit Peak Output Current RTSET = 220Ω Transmit Squelch Voltage Level (Tx+, Tx–) Differential Input Voltage (RxTP+, RxTP–) ±0.300 Receiver Input Resistance 10 SQEN/LTD/JABD Input Resistance 300 Differential Output Voltage (Rx±, COL±) ±550 Common Mode Output Voltage (Rx±, COL±) 4 mV ±3.1 450 kΩ 585 mV-p ±1200 mV V ±40 3.2 SQE TEST disabled All disabled Link Test Disabled All Enabled 1.1 BIAS – 0.15 VCC – 0.05V V kΩ 2 BIAS Voltage Note 2: Note 3: Note 4: Note 5: Note 6: –170 4.0 Differential Output Voltage Imbalance (Rx±, COL±) Note 1: mA 12 Receive Squelch Voltage Level (RxTP+, RxTP–) SQEN/LTD/JABD 42 (Note 6) mV V 0.3 1.4 BIAS + 0.15 V Absolute maximum ratings are limits beyond which the life of the integrated circuit may be impaired. All voltages unless otherwise specified are measured with respect to ground. Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions. Low Duty cycle pulse testing is performed at TA. This does not include the current from the AUI pull down resistors, the transmit pins TxTP+ and TxTP– or the LED output pins. LED drivers can sink up to 20mA, but VOL will be higher. This current will result in a 2.5V peak output voltage on unshielded twisted pair cable when connected through an external filter and transformer as shown in Figure 12. ML4658 ELECTRICAL CHARACTERISTICS (Continued) AC ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER MIN TYP MAX UNITS Transmit t TXNPW Transmit Turn-On Pulse Width 20 ns tTXFPW Transmit Turn-Off Pulse Width 180 ns tTXLP Transmit Loopback Startup Delay 200 ns tTXODY Tranmitter Turn-On Delay 200 ns tTXSDY Transmit Steady State Prop. Delay 15 100 ns tTXJ Transmitter Jitter ±2 ±3.5 ns tRXODY Receive Turn-On Delay if Transmit is Idle 420 500 ns tRXTDY Receive Turn-On Delay if Tranmit is Active 650 800 ns tRXFX Last Bit Received to Start Slow Decay Output tRXSDY Receive Steady State Prop. Delay tRXJ Receiver Jitter tAR Differential Output Rise Time 20% to 80% (Rx±, COL±) 3 ns tAF Differential Output Fall Time 20% to 80% (Rx±, COL±) 3 ns Receive 230 800 ns 15 100 ns ±0.7 ±1.5 ns Collision tCPSQE Collision Present to SQE Assert 0 900 ns tTXRX Time for Loopback to swtich from Tx to RxTP during a collision 0 900 ns Time for SQE to deactivate given that RxTP goes idle and TxTP continues 0 900 ns Time for SQE to deactivate given that TxTP goes idle and RxTP continues 0 900 ns tSQEXR tSQEXT tCLF Collision Frequency 8.5 10 11.5 MHz t CLPDC Collision Pulse Duty Cycle 40 50 60 % tSQEDY SQE Test Delay (Tx Inactive to SQE) 0.6 1.1 1.6 µs tSQETD SQE Test Duration 0.5 1.0 1.5 µs Jabber, Link Test and LED Timing tJAD Jabber Activation Delay 20 70 150 ms tJRT Jabber Reset Unjab Time 250 450 750 ms tJSQE Delay from Outputs Disabled to Collision Oscillator On tLLT Link Loss Time 50 95 150 ms tLTN Link Test Pulse Receive Minimum Time 2 4.2 7 ms tLTX Link Test Pulse Receive Maximum Time 25 70 150 ms tTLP Link Test Pulse Repetition Rate 8 16 24 ms t LTPW Link Test Pulse Width 85 100 200 ns tLEDT XMT, RCV, CLSN On Time 30 100 300 ms 100 ns 5 ML4658 TIMING DIAGRAMS tTXNPW Tx+ VALID Tx– DATA tTXODY tTXSDY tTXFPW TxTP+ VALID TxTP– DATA tTXLP Rx+ VALID Rx– DATA Figure 1. Transmit and Loopback Timing RxTP+ VALID RxTP– tRXODY DATA tRXSDY tRXTDY tRXFX tAR tAF Rx+ Rx– VALID DATA Figure 2. Receive Timing 6 ML4658 TIMING DIAGRAMS (Continued) TxTP+ VALID TxTP– DATA RxTP+ VALID RxTP– DATA tCPSQE COL+ CS0 COL– tTXRX Rx+ Tx Tx Tx RxTP RxTP RxTP Rx– RxTP+ VALID DATA VALID DATA RxTP– TxTP+ TxTP– tCPSQE COL+ CS0 COL– Figure 3. Collision Timing RxTP+ RxTP– TxTP+ VALID TxTP– DATA tSQEXR COL+ CS0 COL– Rx+ Rx– RxTP RxTP Tx Tx Tx Tx Figure 4. Collision Timing 7 ML4658 TIMING DIAGRAMS (Continued) TxTP+ TxTP– RxTP+ VALID RxTP– DATA tSQEXT COL+ CS0 COL– Rx+ Rx– RxTP RxTP RxTP RxTP RxTP 1 tCLF COL+ COL– Figure 5. Collision Timing TxTP+ VALID DATA TxTP– tSQEDY tSQETD COL+ CS0 COL– Figure 6. SQE Timing Tx+ VALID DATA Tx – tJAD TxTP+ TxTP– tJRT VALID DATA tJSQE COL+ CS0 COL– Figure 7. Jabber Timing 8 ML4658 TIMING DIAGRAMS (Continued) RECEIVER FRAME RxTP+ RxTP– LINK PULSE RxTP+ RxTP– tLLT TRANSMIT, RECEIVER LOOPBACK DISABLE LTF tLTN, tLTX RxTP+ RxTP– tTLP TxTP+ TxTP– tLTPW Figure 8. Link Pulse Timing TxTP+ TxTP– tLEDT XMT RxTP+ RxTP– tLEDT RCV Figure 9. LED Timing 9 ML4658 SYSTEM DESCRIPTION Figure 10 shows a typical block diagram of an external 10BASE-T transceiver interface. On one side of the transceiver is the AU interface and the other is the twisted pair. The AU interface is AC coupled when used in an external transceiver or can be AC or DC coupled when used in an internal transceiver. The AU interface for an external transceiver includes isolation transformers, some biasing resistors, and a voltage converter for power. The twisted pair side of the transceiver requires external transmit and receive filters, isolation transformers, and terminating resistors. These components can be obtained in a single hybrid package from suppliers listed in Figure 12. The transmitter sends pre-equalized data through the transmit filters onto the twisted pair. The pre-equalized data uses a standard two step output waveform that lowers the amplitude of the 5MHz component so that at the receiving end both the 5MHz and 10MHz components have the same amplitude. The external transmit filter smooths the edges of the signal before passing it onto the twisted pair. The receive pair side of the transceiver accepts the data after it passes through the isolation transformer and the receive low pass filter. Since this is an AC coupled input, the Bias pin is used to set the proper common mode voltage for the receive inputs. A pair of 50Ω resistors correctly terminate the receive pair and provide a common mode for the Bias voltage connection point. AU INTERFACE The AU interface consists of 3 pairs of signals, DO, CI and DI, as shown in Figure 10. The DO pair contains transmit data from the DTE which is received by the transceiver and sent out onto the twisted pair. The DI pair contains valid data that has been either received from the twisted pair or looped back from the DO and output through the Dl pair to the DTE. The CI pair indicates whether a transmit based collision has occurred. It is an output that oscillates at 10MHz. CI pair is also used for Jabber and SQE Test. The transceiver may be AC or DC coupled depending on the application. For the AC coupled interface, the DO input must be DC biased (shifted up in voltage) for the proper common mode input voltage. The BIAS pin serves this purpose. When DC coupled, the manchester encoder/ decoder transmit output pair provides this common mode voltage and the Bias pin is not connected. The two 39Ω 1% resistors tied to the Tx+ and Tx– pins serve two purposes. They provide a point to connect the common mode bias voltage, and they provide the proper matching termination for the AUI cable. The CI and DI pair, which are output drivers from the transceiver to the AUI cable, require 360Ω pull down resistors when terminated with a 78Ω load. However on a DTE card, CI and DI do not need 78Ω terminating resistors. This also means that the pull down resistors on CI and DI can be 1kΩ or greater depending upon the particular manchester encoder/decoder chip used. +5V TxIN+ VCC D0 TxIN– 39Ω TxTP+ FILTER 39Ω TxTP– COL+ C1 COL– RxTP+ 360Ω 360Ω 50Ω BIAS RxOUT+ D1 360Ω FILTER 50Ω RxTP– 360Ω RxOUT– GND Figure 10. System Block Diagram 10 ML4658 SYSTEM DESCRIPTION (Continued) At the start of a packet transmission, no more than 2 bits are received from the DO circuit and not transmitted onto the twisted pair. The difference between start-up delays (bit loss plus steady-state propagation delay) for any two packets that are separated by 9.6µs or less will not exceed 200ns. The AUI drivers are capable of driving the full 50 meters of cable length and have a rise and fall time of typically 3ns. The rise and fall times match to within 1ns. In the idle state, the outputs go to the same voltage to prevent DC standing current in the isolation transformers. TRANSMISSION The output stage of the transmitter is a current mode switch which develops the output voltage by driving current through the terminating resistor and the output filter. The transmitter employs a center tap 2:1 transformer where the center tap is tied to VCC (5V). While one pin of the transmit pair (TxTP+, TxTP–) is pulled low, the other pin floats. The output pins to the twisted pair wires, TxTP+ and TxTP–, can drive a 100Ω, 150Ωload, or a variety of impedances that are characteristic of the twisted pair wire. RTSET selects the current into the TxTP+, TxTP– pins. This current along with the characteristic impedance of the cable determines the output voltage. The transmit function consists of detecting the presence of data from the AUI DO input (Tx+, Tx–) and driving that data onto the transmit twisted pair (TxTP+, TxTP–). A positive signal on the Tx+ lead relative to the Tx– lead of the DO circuit will result in a positive signal on the TxTP+ lead of the chip with respect to the TxTP– lead. Before data will be transmitted onto the twisted pair from the AU interface, it must exceed the squelch requirements for the DO pair. The Tx squelch circuit serves the function of preventing any noise from being transmitted onto the twisted pair. This circuit rejects signals with pulse widths less than typically 20ns and voltage levels more positive than –175mV. Once the Tx squelch circuit has unsquelched, it looks for the start of idle signal to turn on the squelch circuit again. The transmitter turns on the squelch again when it receives an input signal at Tx± that is more positive than –175mV for more than approximately 180ns. Once the characteristic impedance of the twisted pair is determined, one must select the appropriate RTSET resistor as well as match the terminating impedances of the transmit and receive filter. The RTSET resistor can be selected as follows: RTSET = (RL / 100) × 220Ω where RL is the characteristic impedance of the twisted pair cable. BINARY 0 1 1 1 0 0 1 1 0 TxTP+ TxTP– OUTPUT AFTER TRANSMIT FILTER INPUT INTO RECEIVER Figure 11. Transmit Pre-Equalization Waveform 11 ML4658 SYSTEM DESCRIPTION (Continued) The transmitter incorporates a pre-equalization circuit for driving the twisted pair line. Pre-equalization compensates for the amplitude and phase distortion introduced by the twisted pair cable. The twisted pair line will attenuate the 10MHz signal more than the 5MHz signal. Therefore pre-equalization insures that both the 5 and 10MHz components will be roughly the same amplitude at the far end receiver. The pre-equalization circuit reduces the current output when a 5MHz bit is being transmitted. After 50ns of a 5MHz bit, the current level is reduced to approximately 2/3 of its peak for the remaining 50ns. Figure 11 illustrates the pre-equalization. An on-chip one-shot determines the pulse width of the pre-equalized transmit signal. This requires an external capacitor connected to pins TxCAP0 and TxCAP1. The proper value for this one-shot is 330pF. Pre-equalization can be disabled by shorting TxCAP0 and TxCAP1 together. The transmitter enters the idle state when it detects start of idle on Tx+ and Tx– input pins. The transmitter maintains a minimum differential output voltage of at least 450mV for 250ns after the last low to high transition. The driver differential output voltage will then be within 50mV of 0V within 45 bit times. RECEPTION The twisted pair receive data is transformer coupled and low pass filtered before it is fed into the input pins RxTP±. The input is differential with the common mode voltage set by the chip’s Bias pin. At the start of packet reception from the twisted pair link, no more than 5 bits are received from the twisted pair cable and not transmitted onto the DI circuit. The first bit sent on the DI circuit may contain phase violations or invalid data, but all subsequent bits are valid. The receive squelch will reject the following signals on the RxTP+ and RxTP– inputs: 1. All signals that produce a peak magnitude less than 300mV. 2. All continuous sinusoidal signals of amplitude less than 6.2VP–P and frequency less than 2MHz. 3. All single sinusoidal cycles of amplitude less than 6.2VP–P and either polarity, where the frequency is between 2MHz and 15MHz. For a period of 4 BT before and after this single cycle, the signal will conform to (1) above. 4. All sinusoidal cycles gated by a 100ns pulse gate of amplitude less than 6.2VP–P and either polarity, where the sinusoidal frequency is between 2MHz and 30MHz. The off time of the pulse gate on the sinusoidal signal shall be at least 400ns. 12 The first three receive squelch criteria are required to conform to the 10BASE-T standard. The fourth receive squelch criteria exceeds the 10BASE-T requirements and enhances the performance of the receiver. The fourth squelch criteria prevents a false unsquelch caused by cross talk or noise typically found coupling from the phone lines onto the receive twisted pair. When the receive squelch is on during idle, the input voltage must exceed approximately ±450mV peak several times before unsquelch occurs. If the transmitter is inactive, the receiver has up to 5 bit times to unsquelch and output the receive data on the Rx+, Rx– pair. If the transmitter is active, the receive squelch extends the time it takes to determine whether to unsquelch. If the receiver unsquelches while the transmitter is active, a collision will result. Therefore the receive squelch uses the additional time to insure that a collision will not be reported as a result of a false receive squelch. After the receiver is unsquelched, the detection threshold is lowered to 275mV. Upon passing the receive squelch requirements the receive data propagates into the multiplexer and eventually passes to the Rx+ and Rx– outputs of the AU interface. The addition of jitter through the receive section is no more than ±1.5ns. While in the unsquelch state, the receive squelch circuit looks for the start of idle signal at the end of the packet. When start of idle is detected, receive squelch is turned on again. The proper start of idle occurs when the input signal remains above 300mV for 160ns. Nevertheless, if no transitions occur for 160ns, receive squelch is still turned on. COLLISION Whenever the receiver and the transmitter are active at the same time the chip will activate the collision output. The collision output is a differential square wave matching the AUI specifications and capable of driving a 78Ωload. The frequency of the square wave is 10MHz ±15% with a 60/40 to 40/60 duty cycle. The collision oscillation turns on no more than 9 bit times after the collision condition begins, and turns off no more than 9 bit times after the collision condition is removed. The collision oscillator also is activated during SQE Test and Jabber. LOOPBACK The loopback function emulates a coax Ethernet transceiver where the transmit data sent by the DTE is looped back over the AUI receive pair. Many LAN controllers report the status of the carrier sense for each packet transmitted. The software can use this loopback information to determine whether a MAU is connected to the DTE by checking the status of carrier sense after each packet transmission. ML4658 SYSTEM DESCRIPTION (Continued) When data is received by the chip while transmitting, a collision condition exits. This will cause the collision oscillator to turn on within 9 bit times. The data on the DI AUI pair (Rx+, Rx–) changes from Tx+, Tx– to RxTP+, RxTP–, when entering the collision state. During a collision, if the receive data (RxTP+, RxTP–) drops out before the transmit data (Tx+, Tx–), Rx+, Rx– will switch back to Tx+, Tx–. SQE TEST FUNCTION (SIGNAL QUALITY ERROR) The SQE test function allows the DTE to determine whether the collision detect circuitry is functional. After each transmission, during the inter-packet gap time, the collision oscillator will be activated for typically 1µs. The SQE test will not be activated if the chip is in the link fail state, or the Jabber state. For SQE to operate, the SQEN pin must be tied to VCC or BIAS. The SQE test can be disabled by tying the SQEN pin to 1.2V or ground. This allows the chip to be interfaced to a repeater. JABBER FUNCTION The Jabber function prevents a babbling transmitter from bringing down the network. Within the transceiver is a Jabber timer that starts at the beginning of each transmission and resets at the end of each transmission. If the transmission lasts longer than 20ms the jabber logic disables the transmitter, and turns on the collision oscillator COL+, COL–. When Tx+ and Tx– finally go idle, a second timer measures 0.5 seconds of idle on Tx+ and Tx– before re-enabling the transmitter and turning off the collision oscillator. If transmission starts up again before 0.5 seconds has expired, the timer is reset and measures another 0.5 seconds of idle time. Even though the transmitter is disabled during jabber, Link Pulses are still transmitted if the, Link Test is enabled. Jabber can be disabled by placing 1.2V on the SQEN/ LTD/JABD pin. This is useful for measuring jitter performance on the transmitter. LINK TEST FUNCTION Transmission — Whenever data is not being delivered to the twisted pair link, the idle signal is applied. The idle signal is a sequence of Link Pulses separated by a 16ms period of silence. The idle signal starts with a period of silence after a packet transmission ends. The link test pulse is a single high pulse with the same amplitude requirements as the data signal. Reception — The transceiver monitors the receive twisted pair input for packet and link pulse activity. If neither a packet nor a link test pulse is received for 50 to 150ms, the transceiver enters the Link Test Fail state and inhibits transmission and reception. Link pulses received with the wrong polarity will be ignored and cause the chip to go into link test fail. A DTE can determine that the transceiver is in Link Test Fail one of two ways: it can monitor the LTF pin if the transceiver is internal, or it can monitor loopback. If the MAU is on-board the LTF pin can be sampled to determine that the transceiver is in the link fail state. If the MAU is external the DTE can monitor carrier sense during transmission. A loss of carrier sense is an indication of Link Test Fail State, since in Link Test Fail, loopback is disabled. Note that jabber also disables loopback but with Jabber the collision signal will be on. When a packet, or two consecutive link test pulses is received from the twisted pair input, the transceiver will exit the Link Test Fail state upon transmit and receive data being idle, and re-enable transmission and reception. Link test pulses that do not occur within at most 25 to 150ms of each other are not considered consecutive. In addition, detected pulses that occur within a time between 2 to 7ms of a previous pulse will be considered as noise by the link test circuitry. POLARLITY CIRCUITRY The ML4658 offers automatic polarity correction. The POLRD pin is used to report the status of the receive pair polarity. This pin reflects the true status of the receive polarity regardless of whether the part has autopolarity correction or not. Automatic Polarity Correction — ML4658 — In the link OK state, receive polarity is updated when two consecutive frames are received with the same Start of Idle polarity. In the Link Test Fail state the part will use either the Start of Idle signal or link pulses to correct the receive polarity. In the case where the part is powered up with the receive polarity reversed and no frames are received, the part will go into Link Test Fail. After two link pulses are received with the same polarity, the part will exit Link Test Fail and correct the receive polarity. The POLRD pin will continue to reflect the true polarity of the receive pair. LED DRIVERS The ML4658 has six LED drivers for transmit, receive, collision, Link Test Fail, reverse polarity, and jabber. The LEDs are normally off except for LTF which is normally on and active high. The LEDs are tied to their respective pins through a 510Ω resistor to 5 Volts. The XMT, RCV and CLSN pins have pulse stretchers on them which enables the LEDs to be visible. When transmission or reception occurs, the LED XMT, RCV or CLSN status pins will activate low for 100ms. If another transmit, receive or collision condition occurs during the first 100ms, the LED timer will reset and begin timing again for 100ms. The LEDs will remain on for consecutive frames. The JAB, POLRD, and LTF LEDs do not have pulse stretchers on them since their conditions occur long enough for the eye to see. 13 ML4658 APPLICATION: EXTERNAL MAU 330pF P1 1 9 2 10 3 TxTP+ T1 3 AUI.CP– AUI.CP+ AUI.TX– AUI.TX+ R1 12 5 COL– TxTP– AUI.RX– AUI.RX+ R3 13 * 15 6 7 15 8 +5V 360Ω 2 COL+ 10 RTSET 9 Tx– 39Ω 1KΩ 3.3KΩ BIAS R21 R22 1 3 5 7 2 4 6 8 AUI.PWR– AUI.PWR+ 50Ω BIAS 50Ω D2 D3 D4 D5 D6 D7 510Ω VCC GND 7 17 +5V 560Ω D8 R13 D1 VR1 IN + C1 3µ C2 0.1µ OUT LM340 GND +5V + C3 3µ C4 0.1µ * Single Chip Solutions are Available from Magnetic Suppliers. Magnetics and Filter Suppliers: Pulse Engineering, Inc. (San Diego) Valor Electronics, Inc. (San Diego) Fil-Mag (San Diego) Figure 12. External MAU 14 RJ 45 1:1 +5V LTF RRSET 12 POLRD R16 11 62KΩ, 1% TRANSMIT FILTER +5V R15 220Ω 20 50pF 200Ω 200Ω RxTP– 21 BIAS 1% BIAS 23 R4 39Ω 8 Tx+ 4 6 Rx– SQEN 360Ω R5 1 CLSN JAB 24 R6 14 360Ω RCV Rx+ 5 XMT 13 14 2:1 16 RxTP+ 22 360Ω R2 11 4 C5 19 18 U1 CAP0 CAP1 CHASSIS.REF RECEIVE FILTER ML4658 APPLICATION: INTERNAL MAU 330pF CAP0 CAP1 * 2:1 TxTP+ CP+ 200Ω COL+ 0.1µF ML4658 1kΩ TRANSMIT FILTER +5V 200Ω MANCHESTER ENCODER/DECODER 1kΩ CP– Tx+ 0.1µF COL– TxTP– RxTP+ 50Ω 0.1µF Tx+ BIAS 39Ω Rx+ 0.1µF RxTP– Tx– RTSET 220Ω Rx+ 0.1µF RECEIVE FILTER 50Ω BIAS 39Ω Tx– RJ 45 1:1 RRSET +5V 62kΩ 1% SQEN 1kΩ 510Ω POLRD 1kΩ Rx– 0.1µF Rx– LTF 510Ω 510Ω XMT RCV 510Ω 510Ω JAB 510Ω CLSN VCC GND +5V Figure 13. Internal MAU 15 ML4658 PHYSICAL DIMENSIONS inches (millimeters) Package: P24 24-Pin PDIP 1.240 - 1.260 (31.49 - 32.01) 24 0.530 - 0.560 0.595 - 0.625 (13.46 - 14.23) (15.11 - 15.88) PIN 1 ID 1 0.070 MIN (1.77 MIN) (4 PLACES) 0.050 - 0.065 (1.27 - 1.65) 0.100 BSC (2.54 BSC) 0.015 MIN (0.38 MIN) 0.190 MAX (4.83 MAX) 0.016 - 0.022 (0.40 - 0.56) 0.125 MIN (3.18 MIN) SEATING PLANE 0.008 - 0.012 (0.20 - 0.31) 0º - 15º Package: Q28 28-Pin PLCC 0.485 - 0.495 (12.32 - 12.57) 0.042 - 0.056 (1.07 - 1.42) 0.450 - 0.456 (11.43 - 11.58) 0.025 - 0.045 (0.63 - 1.14) (RADIUS) 1 0.042 - 0.048 (1.07 - 1.22) PIN 1 ID 8 22 0.300 BSC (7.62 BSC) 0.450 - 0.456 0.485 - 0.495 (11.43 - 11.58) (12.32 - 12.57) 15 0.009 - 0.011 (0.23 - 0.28) 0.050 BSC (1.27 BSC) 0.026 - 0.032 (0.66 - 0.81) 0.013 - 0.021 (0.33 - 0.53) 16 0.165 - 0.180 (4.06 - 4.57) SEATING PLANE 0.148 - 0.156 (3.76 - 3.96) 0.099 - 0.110 (2.51 - 2.79) 0.390 - 0.430 (9.90 - 10.92) ML4658 ORDERING INFORMATION © Micro Linear 1998. ORDERING NUMBER AUTO-POLARITY PACKAGE ML4658CP ML4658CQ Yes Yes 24-Pin PDIP (P24N) 28-Pin PLCC (Q28) is a registered trademark of Micro Linear Corporation. All other trademarks are the property of their respective owners. Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376; 5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167; 5,714,897; 5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174; 5,767,653; 5,777,514; 5,793,168; 5,798,635; 5,804,950; 5,808,455; 5,811,999; 5,818,207; 5,818,669; 5,825,165; 5,825,223. Japan: 2,598,946; 2,619,299; 2,704,176; 2,821,714. Other patents are pending. Micro Linear reserves the right to make changes to any product herein to improve reliability, function or design. Micro Linear does not assume any liability arising out of the application or use of any product described herein, neither does it convey any license under its patent right nor the rights of others. The circuits contained in this data sheet are offered as possible applications only. Micro Linear makes no warranties or representations as to whether the illustrated circuits infringe any intellectual property rights of others, and will accept no responsibility or liability for use of any application herein. The customer is urged to consult with appropriate legal counsel before deciding on a particular application. 2092 Concourse Drive San Jose, CA 95131 Tel: (408) 433-5200 Fax: (408) 432-0295 www.microlinear.com DS4658-01 17