DP83849ID: Reciever input voltage for 100Base-FX

Hello Victoria Ross, 

Thank you for the query.

Please refer to 8.1 DC Specs. page 78.

Regards,

Sreenivasa

Hi Sreenivasa,  thanks for the reply! I did look at that table but all I see is the requirements for 100Base-TX and not 100Base-FX. Where are you seeing the specs for 100Base-FX?

Thank you,

Victoria

Hello Victoria, 

Noted. 

Please see below

4.3 100BASE-FX Operation The DP83849ID provides IEEE 802.3 compliant 100BASEFX operation. Configuration of FX mode is via strap option, or through the register interface.

4.3.1 100BASE-FX Transmit In 100BASE-FX mode, the device Transmit Pins connect to an industry standard Fiber Transceiver with PECL signalling through a capacitively coupled circuit. In FX mode, the device bypasses the Scrambler and the MLT3 encoder. This allows for the transmission of serialized 5B4B encoded NRZI data at 125MHz. The only added functionality from 100BASE-TX is the support for Far-End Fault data generation.

4.3.2 100BASE-FX Receive In 100BASE-FX mode, the device Receive pins connect to an industry standard Fiber Transceiver with PECL signalling through a capacitively coupled circuit. In FX mode, the device bypasses MLT3 Decoder and the Descrambler. This allows for the reception of serialized 5B4B encoded NRZI data at 125MHz. The only added functionality for 100BASE-FX from 100BASE-TX is the support of Far-End Fault detection.

We have customers interfacing to the LVPECL capable fiber optic transceiver as below.

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/533252/dual-phyter-dp83849ifvs-media-converter-mode

I hope this helps.

Thanks

Sreenivasa

I am using CML capable fiber optic with a 600mV to 1600mV differential swing. Will that work with the input of this phy?

Hello Victoria Ross, 

Based on the parametric comparison, i would believe that this should work.

Do you have the part number for the tranceiver ? These are legacy parts and so we may not have tested with those transceivers and would need validation from your side.

Regards,

Sreenivasa

The part number is FTLF1323F2GTR. I've attached the datasheet.

 Finisar_FTLF1323F2GTR.pdf

Thank you,

Victoria