DP83867IR: Electrical Enquiry

Hi Chethana,

May I asked what current level  is the VOL for your SoC?

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Regards,

Hillman Lin

Hi Hillman,

Current level and VOL level for the SoC is shown above.

This is the violation.

Thanks & Regards,

Chethana

Hi Chethana,

We have a driver with a high input impedance on the PHY side, so we do not expect the I(oL) should be this big. The load current should be in the microampere range instead of milliampere range.

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Regards,

Hillman Lin

Hi Hilman,

SoC side IOL can be set to 2mA only.

What can be done to resolve this issue?

Is there any alternative way??

Thanks Hilman

Hi Hilman,

Is there any formula to calculate VIL for the Ethernet PHY(DP83867IRRGZR )?

Regards,

Chethana

Hi Chethana,

I look at your SoC specification, they provide the VoL with 8mA output current. Could you double check with the SoC for a lower output current situation for VoL? Our PHY only have microampere current leakage.

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Regards,

Hillman Lin

Hi Hilman,

If we can set the SoC low level output current (IOL) in micro amps, How you can resolve the above issue?

Is there any formula to calculate the VIL of Ethernet PHY?

Thanks & Regards,

Chethana

Adding to the above enquiry,

What IO standard does the TX and RX line of RGMII interface support for all 1V8,2V5 and 3V3 levels.

Hi Chethana,

I am not sure if I understand your problem correctly. Here are the answers for your questions:

• Decreasing IoL (low level output current) will decrease the Value of VoL in the SoC. Could you please check with the SoC on what is the VoL level with a 2mA IoL. From the table you show me above, it has a IoL of 8mA and our PHY normally provide the Leakage current in 2mA. So I want to make sure does the SoC satisfy the VoL level when the IoL is smaller?
• We don't normally provide the calculation of VIL to customer. 
• Voltage levels for RGMII will depend on the VDDIO levels.

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Regards,

Hillman Lin

Thanks Hilman,

We will check with SoC side and  will get back to you soon.

Thanks & Regards,

Chethana

Hi Chethana,

I just want to modify on what I said earlier. Our PHY normally have a leakage current in Microampere and the IEEE standard are in 2mA for the IoL. That is why I want to know what VoL for the SoC when the IoL is in 2mA.

Please let me know if you have more question.

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Regards,

Hillman Lin

Hi Hilman,

This is what we got from our SOC vendor,

1) Setting IOL to a certain value does not change the VOL ,  With a lower drive strength, signal will take simply take more time to reach the required voltage level. 

2) The IOL = 8mA at the SoC side is the maximum value that you can choose in the tool. You can definitely and should set the current strength as per the end device requirement.

So what we can conclude?

Any suggestion from your end?

Best Regards,

Chethana

Hi Chethana,

If we do not get the confirmation that VOL will get smaller with lower value of IoL (2mA) in the SoC, there will be a mismatch between PHY and SOC specification. We cannot sign off for this one. 

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Sincerely,

Hillman Lin