ADIN1110BCPZ-R7 datasheet(24/107 Pages) AD

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Data Sheet

ADIN1110

ON-CHIP DIAGNOSTICS

analog.com

Rev. B | 24 of 107

TEST MODES

The ADIN1110 provides several test modes that allow testing of

the transmitter waveform, distortion, jitter, and droop. These test

modes change only the data symbols provided to the transmitter

circuitry and do not alter the electrical and jitter characteristics of

the transmitter and receiver from the normal operation.

The following test modes included in theADIN1110 are defined in

Subclause 146.5.2 from the IEEE 802.3cg:

►

Test Mode 1. This is a transmitter output voltage and timing jitter

test mode. When this mode is selected, the ADIN1110 repeatedly

transmits the data symbol sequence (+1, –1).

►

Test Mode 2. This is a transmitter output droop test mode. In this

mode, the ADIN1110 transmits ten +1 symbols followed by ten

−1 symbols. This sequence repeats indefinitely.

►

Test Mode 3. Normal operation in idle mode test mode. When

this test mode is selected, the ADIN1110 transmits as in non test

operation and in the master data mode with data set to normal

interframe idle signals.

In addition to these test modes, the ADIN1110 provides the trans-

mit disable mode defined in Subclause 45.2.1.186a.2. This mode

maintains both the receive and transmit path active as in normal

operation, but only transmits 0 symbols. This mode can be used to

measure the MDI return loss specified in Subclause 146.8.3.

Accessing Test Mode 1 to Test Mode 3

To set the ADIN1110 into Test Mode 1, Test Mode 2, or Test

Mode 3, the device must be in software power-down mode

(CRSM_SFT_PD). The power-down status of the ADIN1110

can be checked reading the software power-down status bit

(CRSM_SFT_PD_RDY).

When the ADIN1110 is in software power-down mode, disable

autonegotiation by clearing the autonegotiation enable bit (AN_EN).

With autonegotiation disabled, force the autonegotiation con-

figuration by writing to the autonegotiation forced mode bit

(AN_FRC_MODE_EN).

The desired test mode can now be selected by writing the ap-

propriate value to the 10BASE-T1L test mode control register

(B10L_TEST_MODE_CNTRL) and exiting the device from power-

down by clearing the software power-down bit (CRSM_SFT_PD).

Accessing Transmit Disable Test Mode

To configure the ADIN1110 in the transmit disable test mode, the

device must be in software power-down mode (CRSM_SFT_PD).

The power-down status of the ADIN1110 can be checked reading

the software power-down status bit (CRSM_SFT_PD_RDY).

When the ADIN1110 is in software power-down mode, disable

autonegotiation by clearing the autonegotiation enable bit (AN_EN).

With autonegotiation disabled, force the autonegotiation con-

figuration by writing to the autonegotiation forced mode bit

(AN_FRC_MODE_EN).

The transmit disable test mode can now be enabled by setting the

B10L_TX_DIS_MODE_EN bits to 1. To exit from the test mode,

write 0 to CRSM_SFT_PD.

TIME DOMAIN REFLECTOMETRY (TDR)

Given that the 10BASE-T1L compliant PHY enables communication

over long cables, debugging a faulty cable can become costly and

difficult without the right tools. To help with this, Analog Devices

10BASE-T1L products provide a TDR engine that enables cable

fault detection, distance to fault, and cable length estimation.

The diagnostics solution is the combination of a highly accurate

on-chip TDR engine and a set of algorithms that run on a host

microcontroller, allowing maximum flexibility for a wide variety of

cables and more advanced cable diagnostic capabilities.

Figure 13. ADIN1110 TDR Engine

Fault Detection with the TDR Engine

The Analog Devices algorithm has a time resolution of 8.3 ns,

which translates to a length resolution of less than 1 m and a

maximum of 1600 m, with an accuracy of 2%.

This fault detector algorithm is capable of finding open and short

fault conditions even when the ADIN1110 is physically connected

to another PHY through their MDI, which implies that the link

partner PHY is potentially transmitting DME pages. Traditional TDR

methods struggle to find faults if other signal sources or noise is

also present in the same link. This is not the case of the Analog

Devices solution, which makes it suitable for debugging when there

is no control over the remote end.

The fault detector algorithm is provided as a C-code library con-

taining the high-level functions required for diagnostics. These func-

tions have been optimized to not utilize any advanced processing

so that they can be executed by any low-power microcontroller.

A single function call is sufficient to execute the fault detector. The

function returns the type of fault and the distance to the fault in

meters from the MDI connector.

TDR Offset Calibration

The library includes a function to calibrate the offset of the TDR

measurement. This particular function in the library is useful given

that different MDI circuits may introduce variable delays in the

signal path, which can contribute to the offset of the length meas-

urement. For instance, an isolation transformer on the MDI is highly

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