TXB0104: Logic Level Triggered Issue

Part Number: TXB0104

Hello TI Team,

I am using TXB0104RGYR for bidirectional logic level translation.

Setup Connection:

• VCCA = 1.8V

• VCCB = 3.3V

• A channel and B channel are connected with controller GPIOs

• Both GPIO pins remain floating during idle condition

• A1 channel monitored using DSO probe

Problem Statement:

1. When B1 is connected to logic HIGH (3.3V), A1 correctly transitions from LOW to HIGH (~1.8V).

2. HIGH transition detection works properly.

3. However, when B1 is disconnected (floating condition), A1 remains stuck at HIGH level and does not return LOW.

4. Additionally, when the DSO probe is disconnected and again check at A1 then shows LOW logic level correctly

5. It appears the logic state is being retained/stuck during floating condition

Questions:

1. Is this behavior expected with TXB0104 during floating input conditions?

2. Does TXB0104 have issues with floating GPIO connections?

3. Can DSO probe capacitance affect TXB0104 logic state retention?

4. Is the internal edge accelerator or weak driver causing the output to remain HIGH?

5. What is the recommended method to avoid stuck logic condition during floating/disconnect state?

6. Are external pull-down resistors mandatory for stable operation in this use case?

For reference, I will attach the schematic of my application.

Please suggest the recommended hardware implementation for reliable HIGH/LOW logic detection.

Thank you.