DS90UB948-Q1: Unused input pin

Hi Fadi,

Thank you for your reply.

I understand that the LVDS output of the DS90UB948-Q1 is not connected, but is it also correct to leave the LVDS output of the DS90UB947-Q1 open?

Best Regards,
Ishiwata

Hi Fadi,

Thank you for your answer.

I will make the LVDS input terminals that I do not use floating.

Do LVDS input terminals have a Fail Safe function?

Best Regards,
Ishiwata

Hi Ishiwata,

Open‑LDI/LVDS is straightforward simply add the required 100 Ω differential termination resistor across the LVDS pins. This external termination sets the proper common‑mode voltage, prevents the inputs from floating, and provides a reliable logic level at the receiver. In effect, it serves as a fail safe mechanism, ensuring the input remains in a known state even when no signal is present.

Regards,
Fadi A.

Hi Fadi,

Let me confirm something.
Does the unused LVDS input terminal function as a fail-safe mechanism with a 100Ω external termination resistor?

Or does it function as a fail-safe mechanism even without the 100Ω external termination resistor?

Best Regards,
Ishiwata

Hi Ishiwata,

There is no fail-safe mech within the device itself from LVDS stand-point but adding termination will make it more of "safe" state since it's not floating.

- Fadi A.

Hi Fadi,

Thank you for your answer.
I understand that to ensure a more "safe" state, it's best to install a 100Ω termination resistor on unused LVDS input terminals. Is that correct?

Best Regards,
Ishiwata