DP83TC811-Q1: 100 BASE-T1 Transmitter Output Droop

Kung Poyuan

Part Number: DP83TC811-Q1
Other Parts Discussed in Thread: DP83TC811

I configured the DP83TC811 to Test Mode 1 according to document snla276, but the output speed should be 10BASE-T1. Can you provide the REG settings for 100BASE-T1?

2 months ago

0 Avtar Dhaliwal 2 months ago

TI__Expert 4010 points

Hello Kung,

Our DP83TC811 PHY is only a 100BASE-T1 PHY, it is a single speed PHY with no 10BASE-T1 capability.

Regards,
Avtar

0 Kung Poyuan 2 months ago in reply to Avtar Dhaliwal

Prodigy 30 points

DUT Output is MSI_TM1(R2)

R1 and R3 is standard signal

0 Avtar Dhaliwal 2 months ago in reply to Kung Poyuan

TI__Expert 4010 points

Hello Kung,

I have run test mode 1 on our EVM board, and saw a period of 1.740 us. When looking at our PMA compliance report for Test mode 1 the period is roughly 1.740 us and that test passed compliance. Are you seeing issues passing compliance or are you asking about the period of the waveform?

Regards,

Avtar

0 Kung Poyuan 1 month ago in reply to Avtar Dhaliwal

Prodigy 30 points

About period , because Tektronix standard 100Bast-T1 period is 1.2us

0 Avtar Dhaliwal 1 month ago in reply to Kung Poyuan

TI__Expert 4010 points

Hello Kung,

I see that you have passed for test mode 1, are you maybe referring to the comments where it says signal validation?

Regards,

Avtar

0 Kung Poyuan 1 month ago in reply to Avtar Dhaliwal

Prodigy 30 points

Yes, I compared the standard signal of Tektronix and found the problem shown in the picture above

0 Avtar Dhaliwal 1 month ago in reply to Kung Poyuan

TI__Expert 4010 points

Hello Kung,

I am having trouble finding where Tektronix standard shows 100BASE-T1 period has to be 1.2 ns, I see 100BASE T1 standard says droop has to be atleast 500ns.

Also where is 10BASE-T1 standard saying 1.740 us?

Regards,
Avtar

0 Kung Poyuan 1 month ago in reply to Avtar Dhaliwal

Prodigy 30 points

According to the specifications of 100BASE-T1 (IEEE802.3bw) and the test standards, the definition of Test Mode 1 is as follows in the specification screenshot: Therefore, the period of Test Mode 1 => 34+1/34-1 symbols ~ 40+1/40-1 symbols, and the symbol rate of 100BASE-T1 is 66.66 MHz = 15 ns. The correct period for Test Mode 1 is (34*2)15 ns = 1.02 µs ~ (402)*15 ns = 1.2 µs, which falls within the Tektronix software's check range.

0 Avtar Dhaliwal 1 month ago in reply to Kung Poyuan

TI__Expert 4010 points

Hello Kung,

Thank you for sharing the screenshots, I see however that the minimum value of N shall be 34 symbols in order to achieve a symbol period greater than 500 ns. This is the only hard requirement seen in this document and that is why with a period of 1.740 ns our PHY passes this Test mode 1 compliance.

Regards,

Avtar