DP83867IS PHY analog voltage VDDA1P8 is not coming

Hi Singamareddy,

Yes, during 2 supply operation, you should measure 1.8V on the VDDA1P8 pins if this voltage is being properly generated by the on-chip LDO.

I assume your PHY is not operational when you do not see the 1.8V, is this correct?

Best Regards,

Hi Rob Rodrigues,

Yes you are right PHY is not operational when 1.8V on VDDA1V8 is not coming.

One more query:

1)Is any power sequence need to be followed with 2 supply scheme?

From datasheet we get to know it's not required. If it is true can you please validate this power sequence is ok or not :  VDD1P0(1V)----->VDDIO(1.8V)-------->VDDA2P5(2.5V).

Hi Singamareddy,

No power sequence is needed but all power supplies should be up before 1.8V is available.  Your sequence is OK.  Do you have a reference clock as well?  Have you looked at the voltage on the RBIAS pin?  Is your RBIAS resistor present and 11k 1% tolerance?

Is your DAP on the bottom of the device soldered to the PCB giving a ground return for the device?

Best Regards,

Hi Robert,

Referece clock on the board is generating,it is coming from the crstal of 25MHZ.Yes RBIAS resistor is there and it is of 11K with 1% tolerance.

As you said above, Before 1.8V(VDDIO) comes all voltages has to come.But in my power sequence mentioned above 2.5V(VDDA2P5) is coming after VDDIO.Than is this power sequence is ok?

In your query "Is your DAP on the bottom of the device soldered to the PCB giving a ground return for the device?" I didn't understood term DAP what it is?

Hi Rob Rodrigues,
I do want to know if the above power mentioned power sequence is ok how VDDA1V8 internally generates ?My understanding VDDA1V8 is generating from VDDA2V5 supplied externally.So power sequence will be VDD1P0--->VDDIO(1.8)---->VDDA2P5------>VDDA1V8.Is this ok?

Hi Singamareddy,

The DAP is the large pad located beneath the device that must be connected to the system ground. See the following picture: www.ti.com/.../QFN.png

Your power sequence is OK. You are correct that the 1.8V is derived from the externally supplied 2.5V

Regards,

Hi Rob Rodrigues,
Thank you for your support,

IC was not proper So we replaced the IC with new DP83867IS,IC got detected and we are able to access the PHY IC registers through MDIO interface.
We do facing some new issue after detection of PHY of IC Can you please resolve this issue.
Issue is:
When we connect Laptop and PHY IC thorough RJ45 on EVM, Link between PHY IC and Laptop is not happening which is a basic thing has to happen with any code.

Can you please suggest what could be the issue?

Hi Singamareddy,

I am glad to hear your IC is working now.

For basic troubleshooting steps, please use the following app note: www.ti.com/.../snla246a.pdf

Regards,