DP83849IF: DP8349IF

Hi Andrey,

This depends on the signaling implemented by the SFP module. Typically 100base-fx SFPs use LVPECL, and the DP83849IF is a CML driver.

This app note discusses interfacing a wide range of logic types: www.ti.com/.../scaa059c.pdf

The SFP datasheet usually has a recommendation for connections to a PHY. Do you have a datasheet for the target SFP?

Best Regards,

Hi, Rob!

The DP83849IF has a PECL driver on the receive and transmit lines. This is described in clauses 7.3.1, 7.3.2 of the technical specification for the DP83849IF chip.
The analysis of the optical transceiver connection schemes in the documents snlr004.pdf, snlr002.pdf, as well as documents INF-8074.pdf, OSP155-312xxR_DS.pdf, LSB2-A3S-Px-N5-MM-V1.2.pdf, LM38-A3S- Tx-N-V1.1.pdf I come to the conclusion that the connection scheme of DP83849IF and optical transceiver SFP should be as shown below.

According to INF-8074.pdf, the separation capacitors (0.1 microfarad) can not be installed, since they are already installed in the SFP module.

Correct me if I'm wrong.

LM38-A3S-Tx-N-V1.1.pdf

LSB2-A3S-Px-N5-MM-V1.2.pdf

OSP155-312xxR_DS.pdf

snlr002.pdf

INF-8074.pdf

snlr004.pdf

Hi Andrey,

From the SFP definition, INF-8074, you would not need the 0.1uF caps to AC couple the SFP to the DP83849IF, however not all SFPs may completely follow this spec. For example, the LM38-A3S you linked is AC coupled on both TX and RX diff pairs.

Though it is always a good idea to have a place holder, if possible, with 0 ohm resistors.

Best Regards,

Hi, Rob!

According to the diagram of the connection of DP83849 and SFP module there are comments? Is the termination correct? The translation of the LOS signal is correct?

BR

Andrey

According to the diagram of the connection of DP83849 and SFP module there are comments? Is the termination correct? The translation of the LOS signal is correct?

Hi, Rob!

Any news on my questions?

BR

Andrey