About the VDDD voltage of iMX28

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About the VDDD voltage of iMX28

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yuuki
Contributor V

Would you teach about the voltage of VDDD?

According to the schematic of MX28EVK, the DCDC_VDDD output of i.MX28 is directly inputted into VDDD0-6 of i.MX28.

And, according to a datasheet, when the CPU frequency is set as 454 MHz, Recommended Operating Conditions of VDDD is 1.55V.


The VDDD Supply voltage spec. is the following.
- Digital Core Supply Voltage(VDDD) is Max 1.55V
- Output Voltage Accuracy of VDDD is from -3%  to +3%.

However, Digital Core Supply Voltage of Absolute Maximum Rating is Max 1.55V.

In this case, 1.55V +3% is 1.5965V.

I think that spec. has inconsistency.

When operating CPU at 454 MHz, may we use VDDD=1.55V(+3%: 1.5965V)?


I am referring to the following parts of a datasheet.

http://cache.freescale.com/files/32bit/doc/data_sheet/IMX28CEC.pdf
- Table 6. DC Absolute Maximum Ratings (P.12)
- Table 8. Recommended Power Supply Operating Conditions (P.13)
- Table 13. Power Supply Characteristics (P.15)
- Table 15. Recommended Operating Conditions—CPU Clock (clk_p) (P.16)

Best Regards,

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Yuri
NXP TechSupport
NXP TechSupport

Yuuki-san,

   Strictly speaking, You are right - to be fully of safe side - DCDC_VDDD should
not exceed 1.55V taking into account +3 % tolerance (when DCDC_VDDD is
used to power the VDDD).  

Have a great day,
Yuri

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YixingKong
Senior Contributor IV

Yuuki

We are sorry for getting back to you so late. Are you still stuck with the issue? If you have somehow resolved the issue, can we close the discussion? If you still need help, please feel free to reply with an update to this discussion.

Thanks,

Yixing

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yuuki
Contributor V

Dear Yixing-san,

Thank you for your reply.

This problem has not been solved yet.
I am waiting for the reply from FSL.
Please let me know, if it has some information.

Best Regards,
Yuuki

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YixingKong
Senior Contributor IV

Yuuki-san

I will find a Freescale AE to look into this issue.

Thanks,

Yixing

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