TNETE2101

10BASE-T/100BASE-TX/100BASE-FX

LOW-POWER PHYSICAL-LAYER INTERFACE

SPWS032D – JANUARY 1997 – REVISED MARCH 1999

11

POST OFFICE BOX 655303

link-integrity test and reverse-polarity and correction

When autonegotiation is disabled and the TNETE2101 is configured for 10BASE-T only, the transmitter sends

a normal link pulse through the data-out (DO) circuit every 16 ms.

The receiver looks for valid link pulses on the input pair. If a link pulse is not received within a given time interval,

the device enters a link-fail state. In this state, link pulses continue to be generated, and the receiver

continuously looks for the link pulse pattern. The device remains in this state until a valid receive packet or

multiple legal-link test pulses are received.

Link pulses of the opposite polarity (received and qualified in the same manner as normal link pulses) are an

indication that the receive-pair connections are reversed and that an automatic internal reconfiguration has

occurred to correct this problem. Reverse-polarity correction is not required in 100BASE-TX mode, where the

data is MLT-3-encoded.

autonegotiation

The TNETE2101 fully supports IEEE Std 802.3 autonegotiation, including next-page transfer. When enabled,

this feature allows the TNETE2101 to negotiate with any other autonegotiation-capable PHYs on its link

segment to establish their highest common protocol. Until a PHY has completed its negotiation, it cannot assert

LINK.

More information on the link partner abilities can be obtained by reading the TNETE2101 registers.

loopback test mode

By asserting the CLOOPBK terminal on the device or by setting the LOOPBK bit in the GEN_ctl register, the

transmit circuit of the PHY is looped back to the corresponding receive circuit located closest to the twisted-pair

I/O terminals.

In 10BASE-T mode and loopback mode, all receive activities (other than link test pulses) are ignored. However,

squelch information is still processed, allowing the link status to be maintained under momentary loopback

self-test.

LED status indication

The TNETE2101 has four terminals that drive LEDs, indicating activity, duplex/collision, link, and speed. The

circuitry contains an open-drain N-channel MOS (NMOS) device for the LED driver, and the LEDs should be

connected to digital 3.3 V through a current-limiting resistor. The value of the resistor depends on the LED type.

In 10BASE-T mode, the link LED illuminates when the PHY has established a valid link. In 100BASE-TX mode,

the link LED indicates that the descrambler has locked onto the data and the TNETE2101 is in a state to transmit

and receive data. The link LED flashes during the autonegotiation process to indicate link activity to the user,

since autonegotiation can take several seconds. During loopback test, the LED is not illuminated.

The activity LED illuminates when the PHY is transmitting or receiving data; it remains illuminated for a minimum

of 20 ms for each activity. Its operation is the same in both speed modes. The activity LED illuminates on any

attempt to transmit data, including those made in loopback mode and in link-fail state.

The duplex/collision LED illuminates continuously when the PHY is in full-duplex mode and for a minimum of

20 ms when collisions occur in half-duplex mode. If continuous or frequent collisions occur, it flashes at 10 Hz.

test access port (TAP)

To be compliant with IEEE Std 1149.1 and for boundary-scan testing, the TAP includes five terminals that are

used to interface serially with the device and the board on which it is installed.