DS125DF1610: Need AC coupling Caps?

Go Bravos

Part Number: DS125DF1610

Hi team,

I will be interfacing a DS125DF1610FB with a standard SFP+ 10Gbps optical module. Can you advise whether or not to add AC coupling caps to the Tx line? I have seen some designs that have the caps but, since the caps are internal on the SFP module, I’d rather leave them off my board for better signal integrity.

Thank you.

over 8 years ago

0 Go Bravos over 8 years ago

TI__Expert 6090 points

Hi team,
In addition to my question above, I have an I2C bus pulled to 3.3V connecting directly to the SDA and SCL pins of the DS125. Are these pins partial power-up friendly? Since they will come up before the 2.5V rail, will they cause any powerup problems?

Thank you.

0 Casey Morrison over 8 years ago

TI__Intellectual 1985 points

Hello,

AC coupling capacitors are not required between the DS125DF1610 and the SFP+ connector's TX pins. As you pointed out, these capacitors are included inside the SFP+ module.

Best regards,
Casey

0 Casey Morrison over 8 years ago in reply to Go Bravos

TI__Intellectual 1985 points

Hello,

There is no issue with the implementation you described. Pulling the SCL and SDA pins up to 3.3 V, even if the DS125DF1610 is not powered on, is okay.

Regards,
Casey

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DS125DF1610: Need AC coupling Caps?