TLK105 Datasheet, PDF (15/99 Pages) Texas Instruments – Industrial Temp, Single Port 10/100Mbs Ethernet Physical Layer Transceiver

TLK105
TLK106
www.ti.com
SLLSEB8A – AUGUST 2012 – REVISED MARCH 2013
3.10 BIST
The device incorporates an internal PRBS Built-in Self Test (BIST) circuit to accommodate in-circuit
testing or diagnostics. The BIST circuit can be used to test the integrity of the transmit and receive data
paths. The BIST can be performed using both internal loopback (digital or analog) or external loop back
using a cable fixture. The BIST simulates pseudo-random data transfer scenarios in format of real packets
and Inter-Packet Gap (IPG) on the lines. The BIST allows full control of the packet lengths and of the IPG.
The BIST is implemented with independent transmit and receive paths, with the transmit block generating
a continuous stream of a pseudo-random sequence. The device generates a 15-bit pseudo-random
sequence for the BIST. The received data is compared to the generated pseudo-random data by the BIST
Linear Feedback Shift Register (LFSR) to determine the BIST pass/fail status. The number of error bytes
that the PRBS checker received is stored in the BICSR1 register (0x001Bh). The status of whether the
PRBS checker is locked to the incoming receive bit stream, whether the PRBS has lost sync, and whether
the packet generator is busy, can be read from the BISCR register (0x0016h). While the lock and sync
indications are required to identify the beginning of proper data reception, for any link failures or data
corruption, the best indication is the contents of the the error counter in the BICSR1 register (0x001Bh).
The PRBS test can be put in a continuous mode or single mode by using bit 14 of the BISCR register
(0x0016h). In continuous mode, when one of the PRBS counters reaches the maximum value, the counter
starts counting from zero again. In single mode, when the PRBS counter reaches its maximum value, the
PRBS checker stops counting.
The device allows the user to control the length of the PRBS packet. By programming the BICSR2 register
(0x001Ch) one can set the length of the PRBS packet. There is also an option to generate a single-packet
transmission of two types, 64 and 1518 bytes, through register bit 13 of the BISCR register (0x0016h).
The single generated packet is composed of a constant data.
3.11 Cable Diagnostics
With the vast deployment of Ethernet devices, the need for reliable, comprehensive and user-friendly
cable diagnostic tool is more important than ever. The wide variety of cables, topologies, and connectors
deployed results in the need to non-intrusively identify and report cable faults. The TI cable-diagnostic unit
provides extensive information about cable integrity.
The TLK106 offers the following capabilities in its Cable Diagnostic tools kit:
1. Time Domain Reflectometry (TDR)
2. Active Link Cable Diagnostic (ALCD)
3.11.1 TDR
The TLK106 uses Time Domain Reflectometry (TDR) to determine the quality of the cables, connectors,
and terminations in addition to estimating the cable length. Some of the possible problems that can be
diagnosed include opens, shorts, cable impedance mismatch, bad connectors, termination mismatches,
cross faults, cross shorts and any other discontinuities along the cable.
The TLK106 transmits a test pulse of known amplitude (1V or 2.5V) down each of the two pairs of an
attached cable. The transmitted signal continues down the cable and reflects from each cable
imperfection, fault, bad connector, and from the end of the cable itself. After the pulse transmission the
TLK106 measures the return time and amplitude of all these reflected pulses. This technique enables
measuring the distance and magnitude (impedance) of non-terminated cables (open or short),
discontinuities (bad connectors), and improperly-terminated cables with ±1m accuracy.
The TLK106 also uses data averaging to reduce noise and improve accuracy. The TLK106 can record up
to five reflections within the tested pair. If more than 5 reflections are recorded, the TLK106 saves the first
5 of them. If a cross fault is detected, the TDR saves the first location of the cross fault and up to 4
reflections in the tested channel. The TLK106 TDR can measure cables up to 200m in length.
Copyright © 2012–2013, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: TLK105 TLK106
Hardware Configuration
15