WISMO228 Ring Indicator Pin Drive

Hi guys,

I have been using TXB0104 as a voltage translator between the WISMO228’s ring indicator pin and a microcontroller input pin. It works correctly when an incoming SMS arrived (a low pulse is present).

But, after some longer period of usage, the RI pin seems to stay down instead of going high and not responding to any new SMS arrival anymore.

Is this an issue related to the TXB0104PWR being driven by the RI pin?

Forgot to mention that I have an external pull-up of 10K to 2V8 of the WISMO228 before the TXB0104 translator.
It has been working with this pull-up all the while.
I also know that there’s an internal pull-up of 10K on the RI line.
So, the overall pull-up is 5K.

But, I just got it working again if I remove the external 10K pull-up and replace it with a either a 1K or 5K1 resistor which brings the total pull-up resistance to 0.9K and 3.37K (not very far from the default 5K case?).
So, I can only assume that the RI drive capability is very low?