ML6692 datasheet(13/21 Pages) MICRO-LINEAR

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ML6692

FUNCTIONAL DESCRIPTION (Continued)

does not detect or correct errors in the polarity of fast or

normal link pulses.

USING THE ML6692 WITH AUTOMATIC LINK

CONFIGURATION

The ML6692 supports automated link protocol negotiation

and configuration. In the ML6692, the auto negotiation

state machine checks the receive signal and detects the

presence of link pulses in bursts or singly. The auto

negotiation state machine then updates the status register

in the management logic, and forces the receiver and

transmitter to perform the appropriate function, depending

on the remote link partner and local port capabilities.

If FLP (fast link pulse) bursts are detected, the auto

negotiation state machine disables all protocol-specific

link detection and drives the transmitter with answering

FLP bursts. The auto negotiation state machine then

enables the highest common denominator protocol

between the local port and the remote link partner.

If the highest common denominator technology is

100BASE-TX, the ML6692 100BASE-TX receiver is

enabled. If the highest common denominator technology

is 10BASE-T, the auto negotiation state machine disables

the ML6692 100BASE-TX receiver and enables 10BASE-T

output from the ML6692’s transmitter. If the highest

common denominator technology is 100BASE-T4, the

ML6692’s transmitter and receiver are disabled and the

external 100BASE-T4 transceiver is enabled.

The ML6692 supports the parallel detection function by

checking simultaneously for normal or fast link pulses,

100BASE-TX signal activity at TPINP/N, or indication of

100BASE-T4 activity from the external 100BASE-T4

transceiver. If one of the locally supported protocols is

detected, that protocol is enabled and all others are

disabled. If the local port lacks 10BASE-T capability and

NLPs are detected, the local auto negotiation state

machine disables transmission of all link pulses to force

the far-end station into link fail, and restarts auto-

negotiation.

The ML6692 takes a number of specific actions depending

on which supported technology is selected. If the

100BASE-TX technology is selected, the ML6692 switches

its clock recovery circuit from tracking the local 125MHz

bit clock to tracking the equalized, decoded receive

signal, descrambles, decodes and finds the packet

boundaries of the signal, asserts RXDV, and presents the

decoded receive data nibbles at RXD<3:0>. The ML6692

will also drive 10BTLNKEN and T4EN high to deactivate

external 10BASE-T and 100BASE-T4 transceivers. If the

100BASE-T4 transceiver detects activity, it will drive the

ML6692’s T4FAIL pin high and the ML6692 will place its

receiver and transmitter in an idle state, and will drive

10BTLNKEN high.

With MII Management register bit 0.12 = 0 (auto

negotiation disabled) the ML6692 can be forced into a

certain mode using bits 0.13 (speed select), bit 0.8

(duplex mode), and pin T4FAIL, as shown in the following

table.

SPEED DUPLEX

T4FAIL

MODE

SELECT MODE

100BASE-TX Full Duplex

100BASE-TX Half Duplex

100BASE-T4

10BASE-T Full Duplex

10BASE-T Half Duplex

ML6692 PHY MANAGEMENT FUNCTIONS

The ML6692 has management functions controlled by the

MII Management registers, with several unused locations.

Unused locations are generally reserved for future use.

write). Register 1 (Table 3) is the basic status register

(read-only). Register 4 (Table 4) is the auto-negotiation

capability advertisement register. Register 5 (Table 5) is

the auto-negotiation link partner ability register (what the

far-end station is capable of; read-only). Register 6 (Table

6) is the auto-negotiation expansion register (indicates

some additional auto-negotiation status information; read-

only). Note that status bits 1.11-1.12 (10BASE-T

capability) and 1.15 (100BASE-T4) depend on the values

programmed through the Initialization Interface. See the

initialization interface section for programming

information. The ML6692 powers on with all management

The ML6692’s auto negotiation status and control register

addresses and functions match those described for the MII

in IEEE 802.3u section 22. IEEE 802.3u specifies the

management data frame structure in section 22.2.4.4.

See the IEEE 802.3u Specification section 28 for auto

negotiation state machine definition, FLP timing, and

overall operation.

See IEEE 802.3u section 22.2.4 for a discussion of MII

management functions and status/control register

definitions.

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