DP83822I: DC and AC overshoot & undershoot values are missing in the datasheet for the I/O lines.

Komal Charan Garlapati

Part Number: DP83822I

Hi,

I want to perform the Signal integrity analysis for the RGMII interface. I need to know the maximum allowed voltages for the RGMII signals. I am using VDDIO as 1.8V. In the Electrical Characteristics, for VDDIO = 1.8V, the VIH min is 1.3V but the max value is not given. What is the allowed DC and AC overshoot ? Similarly for VIL, max is 0.5V but what is the allowed DC and AC undershoot?

over 5 years ago

0 Justin Lazaruk over 5 years ago

TI__Expert 7040 points

Hi Komal,

The maximum DC overshoot for VDDIO set to 1.8V is 1.89V and the minimum DC undershoot is 0V. This is found in the recommended operating conditions section of the datasheet. We do not specify an AC maximum over/under but it would not be recommended to exceed the Absolute Maximum ratings on the pins.

Regards,
Justin

0 Komal Charan Garlapati over 5 years ago in reply to Justin Lazaruk

Prodigy 80 points

Thanks for the info, Justin.

Since the min is mentioned as 1.71V in the Recommended Operating Conditions, I thought it is only speaking about the Power Supply Voltage and not the I/O levels.

0 PRAHLAD Supeda over 5 years ago in reply to Justin Lazaruk

TI__Expert 6150 points

Hi Justin,

Could you please confirm below:

VOH_min = VDDIO_min-0.4 = 1.71-0.4 = 1.67V
VOH_max = 1.89V
VOL_min = 0V
VOL_max = 0.4V

0 Justin Lazaruk over 5 years ago in reply to PRAHLAD Supeda

TI__Expert 7040 points

Hi Prahlad,

The levels you provided are the correct datasheet limits for output voltage of I/O pins at VDDIO = 1.8V.

The VOH min with VDDIO set to 1.8V is the following: VDDIO_MIN (1.71V) - 0.4V = 1.31V.

Regards,
Justin

0 PRAHLAD Supeda over 5 years ago in reply to Justin Lazaruk

TI__Expert 6150 points

Hi Justin,

Forgive me for bad maths. Thanks for confirmation.

Komal, Do you need further details ?

0 Komal Charan Garlapati over 5 years ago in reply to PRAHLAD Supeda

Prodigy 80 points

Thank you very much guys. :)

No further details needed, Justin.

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DP83822I: DC and AC overshoot & undershoot values are missing in the datasheet for the I/O lines.