DP83848 Calculating the Minimum Recommended Capacitance

Taichi Noda

Hi,All

Let me ask you a question about an application report"AN-519 DP83848 PHYTER Transformerless Ethernet Operation" of DS83848.

On an application report P11,a sentence"The ANSI standard also specifies a limitation on the phase angle of the load(+/-3°　maximum)" is written.

What does +/-3°　mean?

I am looking forward to your reply.

Best regards.

over 11 years ago

0 Patrick OFarrell over 11 years ago

TI__Mastermind 31600 points

This refers to the clause in the ANSI X3.263-1995 FDDI TPPMD specification on return loss. According to the specification, the impedance should be resistive with a magnitude of phase angle less than 3 degrees over the specified frequency range. The calculations for the capacitor sizes in transformerless operation are intended to make sure that this phase angle meets the ANSI specification.

Patrick

0 Taichi Noda over 11 years ago in reply to Patrick OFarrell

Expert 1350 points

Hello,Mr.Patrick

Thank you for quick reply.

In the case of next usage supposition on following diagram , Equation(1),(3) of AN-1519 come into effect ?

I am looking forward to your reply.

Best regards.

0 Patrick OFarrell over 11 years ago in reply to Taichi Noda

TI__Mastermind 31600 points

The DP83848 cannot support the configuration shown in the "next usage supposition" image. 100Base-T Ethernet supports one to one connections. It cannot support the connection of multiple link partners in a star configuration.

Patrick

0 Taichi Noda over 11 years ago in reply to Patrick OFarrell

Expert 1350 points

Hello,Mr.Patrick

Thank you for quick reply.

I understood that you wrote.

Best regards.

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DP83848 Calculating the Minimum Recommended Capacitance