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TXS0108E: if the waveform from portB of TXS0108E is normal?

zhiheng liu
Prodigy 10 points
Part Number: TXS0108E

Hi，Johnny

我们的应用场景如下，

测试到的波形如下：

蓝色为A-PORT输入，黄色为B-PORT输出

理论上黄色波形应为高电平3.3V的方波，但实测高电平为2.5V左右，上升沿有瞬间冲到3.3V左右然后回落2.5V；

请帮忙确认下为何会出现这种情况？这种情况是否正常？谢谢！

 

  • 0
    Guru 243980 points

    Your actual circuit has a load that is not shown in the schematic. The edge accelerators of the TXS work only for a few nanoseconds; after that, the voltage is held high only by the internal 4 kΩ pull-up resistor. So I guess you have a pull-down resistor with about 12.5 kΩ, or a current sink with about 200 µA.

  • 0
    TI__Genius 16270 points

    Hey Zhiheng,

    Welcome to E2E forums! It is strongly recommended to remove the pull down resistors as TXS family devices have internal pull up resistors. Combining these two elements will create a voltage divider and cause a decrease in VOH levels. See this app note for more information.

    Regards,

    Jack