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TXS0108E: the high signal is pulled down .

user503335153
Intellectual 810 points

Part Number: TXS0108E

TXS0108E ，port  A is 1.8V,port B is 3.3V,  as Voltage Converter for  IIC and  SPI ,the test wave is IIC BUS ,blue and green line is 3.3V  out put ,pink and yellow line is 1.8V  input.The problem is the input of 1.8V, when the two signal lines are high or low, the high level will be pulled down.  the  10k or 2k  pull-up  resistor is used on PORT A and  PORT B.

  • 0
    TI__Guru 64010 points
    Hi,

    It seems that the translation is happening as required from 1.8 to 3.3V on the lines. The input yellow signal seems abnormal to me.
    AS i see, the waveform is not reaching all the way to 1.8V on most cycle and few time cycle reaches high up to 1.8V. why is that? Is this a different configuration on the I2C interface?
    I would not advise having strong pullup resistors. It will increase the Vol voltage level with increased current flowing into the driver device. Please refer to the app note on effects of pullup resistors on TXS.
    www.ti.com/.../scea054a.pdf