Teledyne-lecroy QPHY-ENET Manuel d'utilisateur télécharger pdf (Page 28)

QPHY-ENET Operator’s Manual Rev G

10Base-T TP_IDL Mask Test

This test measures the wave shape of the TP_IDL signal at the output of the MAU. This signal is sent over the

interface to indicate that the Device Under Test is ready to receive data. In this configuration, the TP_IDL signal is

an end-of-packet indicator. The TP_IDL begins with a positive transition and must remain at a positive voltage

level for between 2.5 and 4.5 bit times before going negative. Once the signal goes negative (below -50 mV) it

may not exceed +50 mV. The signal may not exceed +/- 50 mV after 45 bit periods. These requirements are built

into the masks in the measurement software.

The masks are broken into two parts: head and tail. The head mask includes the limits from the first transition out

to 20 bit intervals. The tail mask contains the requirements beyond 20 bit intervals. The mask test must pass for

two different test loads (LOAD1 and LOAD2) and is performed with and without the Twisted Pair Model. The

configuration provided in QualiPHY also test with 100 Ω load, although this is not required by the standard, it may

help debug faulty devices.

Figure 18. Fixture setup for TP_IDL test

1. Connect DUT to J13 and oscilloscope to the section A of TF-ENET-B as shown in

Figure 18

2. Install jumpers in this section to test for Twisted Pair Model (TPM) LOAD1. Refer to Table 2 (previous).

3. Set the DUT to transmit Pseudo Random data.

Note: The method for setting the Device Under Test into transmit mode is device specific. Contact your PHY chip vendor for information on

how to do this.

4. Touch the 10Base-T button under “Select Standard.”

5. Select TP_IDL Head Mask in the “Select Test” field. You should check the Average Result checkbox so

that the test is performed on an averaged waveform. Averaging reduces the noise in the trace.

6. Touch the Set Up and Start Test button to begin testing. The software will search for the TP_IDL pulse

and center it within the mask automatically.

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Teledyne-lecroy QPHY-ENET Manuel d'utilisateur Page 28