[DP83867IR] RGMII 1.8V connection

Takahiro Ogo

Other Parts Discussed in Thread: DP83867IR

Hi,

My customer wants to connection DP83867IR with AM335x using RGMII interface. Also, they want to use it by 1.8V VDDIO.
I are looking at "Electrical Characteristics" of both device's datasheet to check these connection.

In summary,

AM335x DP83867IR

VOH:1.35V(min) => VIH 1.26V(min)

VOL:0.45V(max) => VIL 0.35V(max) ###"VOL > VIL" NG!!!

VIH:1.17V(min) <= VOH 1.26V(min)

VIL:0.45V(max) <= VOL 0.35V(max)

[VDDIO=1.8V]

So, in case of 1.8V VDDIO, DP83867IR can NOT connect with AM335x.

Is my understanding correct?

Best Regards,

Taka

over 8 years ago

0 Aniruddha Khadye over 8 years ago

TI__Mastermind 18425 points

Hello Taka,

Your intepretation of the numbers is correct but the mismatch will not cause any problem with operation. DP83867IR will work with AM335x at 1.8V.

-Regards,
Aniruddha

0 Takahiro Ogo over 8 years ago in reply to Aniruddha Khadye

Genius 5940 points

Hi Aniruddha,

Thank you for your kind support.

Aniruddha Khadye said:
Hello Taka,

Your intepretation of the numbers is correct but the mismatch will not cause any problem with operation. DP83867IR will work with AM335x at 1.8V.

Sorry, I don't understand that. This mismatch will not cause any problem with operation?
Why is there no problem even if "AM335x VOL > DP83867 VIL" ?

Best Regards,
Taka

0 Ross Pimentel over 8 years ago in reply to Takahiro Ogo

TI__Mastermind 23675 points

Hi Taka,

I am looking into this now.

Kind regards,
Ross
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0 Rob Rodrigues over 8 years ago in reply to Ross Pimentel

TI__Mastermind 19780 points

Hi Takahiro-san,

The mismatch in logic level compatibility with the AM series of processors has to do with the test conditions of the processor outputs, where Iol = 6mA. 6mA is very high and their guaranteed Vol is high as well. The DP83867 follows the JEDEC 8-5A standard for 1.8V CMOS levels which specifies Vil 0.2 * VDD.

The DP83867 can support a Vil of 0.6V, which is compatible with the AM335x family of processors.

Regards,
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0 Takahiro Ogo over 8 years ago in reply to Rob Rodrigues

Genius 5940 points

Hi Rob-san,

Oh! the DP83867 can suppor a Vil of 0.6 even if VDDIO supply voltage is 1.8V.
Thank you for your great support!

Best Regards,
Takahiro Ogo.
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[DP83867IR] RGMII 1.8V connection