DP83822I: RMII Master mode 50-MHz Reference Clock Accuracy and Rise/Fall Time value requirement

Rohidas Sawant76

Part Number: DP83822I

Hello,

We are using DP83822I PHY in RMII master mode in our design.

We have required DP83822I PHY Output 50-MHz Reference Clock Accuracy values and Clock Rise/Fall Timing values for design calculations.

Please convey the same.

Regards,

Rohidas

over 4 years ago

0 Vikram Sharma over 4 years ago

TI__Genius 16030 points

Hello Rohidas,

50 MHz clock will have the same accuracy as the 25MHz reference clock. If 25MHz is +/50ppm then 50MHz will also be +/50ppm.

Rise/fall time depends upon the load cap. Approximate number is < 1ns for 5pF of cap.

Regards,

Vikram

0 Rohidas Sawant76 over 4 years ago

Intellectual 370 points

Hello Sir,

Thanks for feedback.

Is there any reference document of PHY in which rise/fall time is mentioned

Regards,

Rohidas

0 Vikram Sharma over 4 years ago in reply to Rohidas Sawant76

TI__Genius 16030 points

Hello Rohidas,

As mentioned, rise/fall time depends upon the load on the pin. If accurate rise/fall times ar required then you may simulate the IBIS model with the required load.

https://www.ti.com/lit/zip/snlm205

Regards,

Vikram

0 Ramdas Tibile over 3 years ago in reply to Vikram Sharma

Prodigy 70 points

Hello TI Team,

I am using same PHY IC and RMII Mode 50MHz Reference clock.

In my design MCU MAC have input pin load capacitance is 8pF. So, what will be the rise/fall time?

Thanks and Regards,

Ramdas

0 Vikram Sharma over 3 years ago in reply to Ramdas Tibile

TI__Genius 16030 points

Hello Ramdas,

It will be better/more accurate to simulate your board + load cap with ibis model. https://www.ti.com/lit/zip/snlm205

Regards,

Vikram

0 Ramdas Tibile over 3 years ago in reply to Vikram Sharma

Prodigy 70 points

Hello Vikram San,

We don't have facility to simulate ibis model.

Can you please suggest rise/fall time with 8pF load capacitance?

0 Vikram Sharma over 3 years ago in reply to Ramdas Tibile

TI__Genius 16030 points

Hello Ramdas,

Without any extracted load of traces I can approximate it to be ~2ns. But we can't guarantee and if critical do refer to board level simulations.

Regards,

Vikram

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DP83822I: RMII Master mode 50-MHz Reference Clock Accuracy and Rise/Fall Time value requirement