ONET1151P: ONET1151P/L 10G SFP+ Reference Design Question

Daniel Drake

Part Number: ONET1151P

Hello everyone,

I am looking at the reference design for building a SFP+ model and I noticed something weird.

The design expects a 3.3V source coming into the device via VCCR and VCCT.

This voltage is then fed into a Step-Down Converter, TPS82693SIP which then provides a 2.85V source to the rest of the parts in the system.

Why is this being done?

The chips in the system are all rated to use a 3.3V source as VCC.

It seems strange to do this when it might cause some the parts to brown out.

I'm not an expert in electrical engineering so keep that in mind. lol

Reference design:

0 Nasser Mohammadi over 5 years ago

Hi Daniel,

I agree most of the SFPs use 3.3V supply. ROSA and TOSA used on this reference design was checked using 2.85V instead.

Please below note a reference design using SFP with 3.3V supply:

Regards,, Nasser

0 Daniel Drake over 5 years ago in reply to Nasser Mohammadi

So you are saying that because the ROSA and TOSA were rated for a lower voltage, they decided to use that voltage for the rest of the parts?

They didn't post the part references for the ROSA and TOSA so I can't confirm this. Do you have the references?

The design you referenced as far as I can tell is for integrating a SFP module into a design and not an actual design for an sfp module.

What I'm interested in is the actual SFP module design itself.

0 Nasser Mohammadi over 5 years ago in reply to Daniel Drake

Hi Daniel,

ROSA/TOSA on these module operate from 2.85 to 3.6V. Front end circuitry or interface to the laser was tuned using 2.85V supply.

Regards,,, Nasser

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