DP83848I PFBOUT voltage regulation

Yoko Sumiyoshi

Prodigy 40 points

Dear Sirs,

To decide voltage absolute maximum rating of 10uF TANTALUM capacitor, I want to know PFBOUT pin output voltage range.

Question 1)

If I am not wrong, It should be 1.73Vdc minimun, 1.8Vdc maximum. Is this guaranteed value?

I just consider about guaranteed maximum voltage includes ripple noise.

Question 2)

If we use not 10uF, 22uF or more, what will be happened?

Thank you for your support.

-Yoko-

over 11 years ago

0 John Griffith over 11 years ago

TI__Mastermind 21501 points

Hi,

To help with better supporting questions in Ethernet, there is now an Ethernet forum for Ethernet PHYs, Ethernet MACs and Ethernet SerDes. Please post any new Ethernet related questions into this forum.

Thanks!

John

0 Patrick OFarrell over 11 years ago in reply to John Griffith

TI__Mastermind 31600 points

Yoko,

The nominal value for the PFBOUT pin should be 1.8V, but some device to device variation of this voltage is expected. A value of 1.73V is within expected variation.

The Tantalum capacitor is the load for an internal regulator which generates a 1.8V supply for the device. Changing the value of the capacitor from 10uF could affect the functionality of the internal regulator. Using a 10uF capacitor is recommended.

Patrick

0 Yoko Sumiyoshi over 11 years ago in reply to John Griffith

Prodigy 40 points

Hi John,

Thank you for your notice and moving the thread to Ethernet forum.

From next time, I will post my question about PHY on Ethernet forum not on industrial interface forum.

Thank you again.

Yoko

0 Yoko Sumiyoshi over 11 years ago in reply to Patrick OFarrell

Prodigy 40 points

Hi Patrick

Thank you for your reply.

I have additional question.

(1) Our circuit PFBOUT and PFBIN1,PFBIN2 are 1.72V. Is this also expected value?

(2) You said, 1.8V is nominal. So, what is maxim voltage? I want to know both of minimum and maximum value of PFBOUT when VDD=3.3V+/-5%

Thank you so much for your support.

Yoko

0 Patrick OFarrell over 11 years ago in reply to Yoko Sumiyoshi

TI__Mastermind 31600 points

Yoko,

For variation over normal environmental conditions (process, voltage, and temperature), the PFBOUT value can vary +/- 10%. Therefore, 1.72V is within the range of normal operation.

Patrick

0 Yoko Sumiyoshi over 11 years ago in reply to Patrick OFarrell

Prodigy 40 points

Thank you Patrick!

I am clear.

I will choose Tantalum capacitor rated voltage to follow PFBOUT voltage = 1.62V min, 1.8V typ, 1.98V max.

Thanks a lot.

Yoko

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DP83848I PFBOUT voltage regulation