DP83822I: Compliance test Fail : differential Output Voltage

downey KIM

Part Number: DP83822I

Hello, TI team.

The customer failed the Ethernet compliance test (output voltage). please refer to the picture below.

1. According to the data sheet, register settings (0x0403) can control the output voltage. and the data sheet has the output voltage maximum of 2.1V. Compliance test results are +Vout 1.2V, -Vout 1.2V. Higher than the maximum voltage you can set. What's the cause?

2. attach the schematic. please review what is wrong. what should we try to pass the compliance test?

3. What is the role of pin 16 (RBIAS)?

4. What changes do make when change to another value other than 4.87kohm?

I'll wait for an answer. help me solve the problem.

Thanks & Regards.

over 7 years ago

0 Hung Nguyen92 over 7 years ago

TI__Expert 5670 points

Hello,

A 4.87-kΩ ±1% resistor must be connected from pin 16 (RBIAS) to GND, to provide reference current to the internal circuits.

Can you also provide the schematic and part number of magnetic the customer use?

Regards,

Hung Nguyen

0 downey KIM over 7 years ago in reply to Hung Nguyen92

Intellectual 600 points

Hi Hung,

Is the 'magnetic part' talking about R.no L3004 & L3005?

part number is DLW21SN900SQ2L(murata).

I think it is not a problem of choke coil because it is used in many models.

Thanks & Regards

Downey.kim

0 Hung Nguyen92 over 6 years ago in reply to downey KIM

TI__Expert 5670 points

Hi Downey,

That is common mode choke coil. Do you have a transformer in your design?

Regards,

Hung Nguyen

0 Hung Nguyen92 over 6 years ago in reply to Hung Nguyen92

TI__Expert 5670 points

Hi Downey,

I haven’t heard back from you, I’m assuming you were able to resolve your issue.

I will go ahead and close this thread. If you need further support, kindly open new thread.

Regards,

Hung Nguyen

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DP83822I: Compliance test Fail : differential Output Voltage