TXB level shifters have strict requirements on the input and output signals; see sections 8.3.2, 8.3.4, and 8.3.5 of the datasheet:

the device driving the data I/Os of the TXB0106-Q1 device must have drive strength of at least ±2 mA

TI recommends careful PCB layout practices with short PCB trace lengths to avoid excessive capacitive loading and to ensure that proper one-shot (O.S.) triggering takes place. […]

The output drivers of the TXB0106-Q1 device have low dc drive strength. If pullup or pulldown resistors are connected externally to the data I/Os, their values must be kept higher than 50 kΩ to ensure that they do not contend with the output drivers of the TXB0106-Q1 device.

It is possible that you circuit does not comply with these requirements. Please show the schematic, especially all components connected to any of the I/Os.

Hi Kelly,

I concur with Clemens on this. Can you also elaborate more on what you mean by not working?

It could be the load issue. SPI is between MCU and sensor. MCU on one board, sensor on another board. SPI interface between them is connected through connector. The total trace length is 50mm while 45mm is trace over flexible PCB which may add trace capacitance mostly since the microstripe over plane distance is only 1mil. 

UART is MCU talk to PC through USB to RS232 adapter. The adapter TTL-232R-3V3-PCB which use FT232R from FTDI chip.  PCB trace is not long, but the off board connector wire is long. 

If TXB0601 does not support this kind of application, do you have recommendations? 

Thanks,

Thank you very much.