TLK110 Datasheet, PDF (35/104 Pages) Texas Instruments – Industrial Temp, Single Port 10/100Mbs Ethernet Physical Layer

TLK110
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SLLS901A – DECEMBER 2011 – REVISED FEBRUARY 2012
5.5.1 Operation
Auto negotiation uses the 10B-T link pulses. It encapsulates the transmitted data in sequence of pulses,
also referred to as a Fast Link Pulses (FLP) burst. The FLP Burst consists of a series of closely spaced
10B-T link integrity test pulses that form an alternating clock/data sequence. Extraction of the data bits
from the FLP Burst yields a Link Code Word that identifies the operational modes supported by the remote
device, as well as some information used for the auto negotiation function’s handshake mechanism.
The information exchanged between the devices during the auto-negotiation process consists of the
devices' abilities such as duplex support and speed. It allows higher levels of the network (MAC) to send
to the other link partner vendor-specific data (via the Next Page mechanism, see below), and provides the
mechanism for both parties to agree on the highest performance mode of operation.
When auto negotiation has started, the TLK110 transmits FLP on one twisted pair and listens on the other,
thus trying to find out whether the other link partner supports the auto negotiation function as well. The
decision on what pair to transmit/listen depends on the MDI/MDI-X state. If the other link partner activates
auto negotiation, then the two parties begin to exchange their information. If the other link partner is a
legacy PHY or does not activate the auto negotiation, then the TLK110 uses the parallel detection
function, as described in IEEE802.3 chapters 40 and 28, to determine 10B-T or 100B-TX operation
modes.
5.5.2 Initialization and Restart
The TLK110 initiates the auto negotiation function if it is enabled through the configuration jumper options
AN_EN, AN_1 and AN_0 (pins 34,35,36) and one of the following events has happened:
1. Hardware reset de-assertion.
2. Software reset (via register).
3. Auto negotiation restart (via register BMCR (0x0000h) bit 9).
4. Power-up sequence (via register BMCR (0x0000h) bit 11 ).
The auto-negotiation function is also initiated when the auto-negotiation enable bit is set in register BMCR
(0x0000h) bit 12 and one of the following events has happened:
1. Software restart.
2. Transitioning to link_fail state, as described in IEEE802.3.
To disable the auto-negotiation function during operation, clear register BMCR (0x0000h) bit 12. During
operation, setting/resetting this register does not affect the TLK110 operation. For the changes to take
place, issue a restart command through register BMCR (0x0000h) bit 9.
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Architecture
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