TLK100_11 Datasheet, PDF (31/88 Pages) Texas Instruments – Industrial Temp, Single Port 10/100 Mb/s Ethernet Physical Layer Transceiver

TLK100
www.ti.com
SLLS931B – AUGUST 2009 – REVISED DECEMBER 2009
5.3.3 Jabber Function
Jabber is a condition in which a station transmits for a period of time longer than the maximum permissible
packet length, usually due to a fault condition. The jabber function monitors the TLK100 output and
disables the transmitter if it attempts to transmit a packet of longer than legal size. A jabber timer monitors
the transmitter and disables the transmission if the transmitter is active for approximately 100ms.
When disabled by the Jabber function, the transmitter stays disabled for the entire time that the ENDEC
module's internal transmit enable is asserted. This signal must be de-asserted for approximately 500ms
(the unjab time) before the Jabber function re-enables the transmit outputs.
The Jabber function is only available and active in 10BASE-T mode.
5.3.4 Automatic Link Polarity Detection and Correction
Swapping the wires within the twisted pair causes polarity errors. Wrong polarity affects the 10B-T PHYs.
The 100B-TX is invulnerable to polarity problems because it uses MLT3 encoding. The 10B-T
automatically detects reversed polarity according to the received link pulses or data.
5.3.5 10Base-T Transmit and Receive Filtering
External 10BASE-T filters are not required when using the TLK100, as the required signal conditioning is
integrated into the device. Only isolation transformers and impedance matching resistors are required for
the 10BASE-T transmit and receive interface. The internal transmit filtering ensures that all the harmonics
in the transmit signal are attenuated by at least 30dB.
5.3.6 10Base-T Operational Modes
The TLK100 has two basic 10BASE-T operational modes:
• Half Duplex mode – In Half Duplex mode the TLK100 functions as a standard IEEE 802.3 10BASE-T
transceiver supporting the CSMA/CD protocol.
• Full Duplex mode – In Full Duplex mode the TLK100 is capable of simultaneously transmitting and
receiving without asserting the collision signal. The TLK100 10 Mb/s ENDEC is designed to encode
and decode simultaneously.
5.4 Auto MDI/MDI-X Crossover
The auto MDI/MDI-X crossover function detects wire crossover (also referred to as MDI/MDI-X). It
automatically performs the pair swaps such that each transmitter is connected to its link partner receiver
and vice versa, without using an external crossed cable. The auto MDI/MDI-X crossover function is
capable of establishing a link with PHYs that do not implement a cross over mechanism.
Table 5-2. MDI/MDI-X Pair Swaps Combinations
PIN
TD± (pin 8,9)
RD± (pin 5,6)
MDI
10B-T
100B-TX
TD
TD
RD
RD
MDI-X
10B-T
100B-TX
RD
RD
TD
TD
Detecting link pulses or energy on one or more of the MDI pins determines the crossover state and
whether there is a need to perform a swap. If both link partners implement the MDI/MDI-X crossover, then
a random algorithm, compliant with one described in IEEE 802.3 section 40.4.4 is used. If the other link
partner is a legacy 10B-T PHY then the same algorithm is used. If the other link partner is a legacy
100B-TX PHY, then the crossover state is determined according to the signal detection function.
As described, the link partners’ configuration and abilities, whether they use the auto negotiation and/or
activate a crossover mechanism, greatly influence the method picked by the crossover function to
Copyright © 2009, Texas Instruments Incorporated
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