TXB0108: About TXS0108 output oscillation problem

Gabriel Wang1

Part Number: TXB0108
Other Parts Discussed in Thread: DS110DF410, TXS0108E, TCA9803

1. The connection topology of TXS0108 is as follows: When the number of DS110DF410 mounted to the IIC bus is 8, the OUTPUT of SCL and SDA is normal.However, when the number of DS110DF410 exceeds 12, SCL and SDA output oscillations with the following waveform.

The waveform of SDC measured at the pin of TXS0108

The waveform of SDA measured at the pin of TXS0108

2. Two questions in total: First, why does it oscillate?What are the conditions that cause oscillations?Second, what is the solution?

over 4 years ago

0 Clemens Ladisch over 4 years ago

Guru 316150 points

The TXS0108E has edge accelerators, which try to detect the beginning of a rising or falling edge, and amplify it. If your signals have so much capacitance or inducance that there is ringing, the TXS might detect false edges, which results in oscillations.

(The TXS has internal pull-up resistors; you should not need the external ones.)

The TXS is designed for small boards with high-speed signals. For long I²C traces, a buffered I²C translator like the TCA9803 would be much more robust.

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TXB0108: About TXS0108 output oscillation problem