TCA9617B: I2C SDA NACK

Part Number: TCA9617B


HI TI team:

In my application, TCA9617 is used as the I2C level converter(3.3V->1.8V), and the circuit diagram is as follows:

B side: Controller

A side: Target

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During debugging, it was found that I2C communication is unstable. Use a logic analyzer to capture the waveform as follows:

  1. When the probe is connected to the B side, NACK occurs in I2C communication, and the retry may return to normal. 
  2. When the probe is connected to the A side, I2C communication becomes stable (even without retry).  

Why does connecting logic analyzer/oscilloscope probes on I2C bus improve communication stability? How can I fix this issue?

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