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TXS0108E: TXS0108E oscillation problem

Frank Xiao
Genius 12055 points
Part Number: TXS0108E
Other Parts Discussed in Thread: SN74LV4T125

Hi team,

My customer is using the TXS0108E now. The MCU GPIO control the LED array with TXS0108S to change 3.3v to 5v. There are some high frequency oscillation happen. The frequency is about 40Mhz. I have let the customer remove the TXS0108S, the oscillation disappear. Could you please help check why? Thanks.

We do the test below.

The schematic 

The ouput connect the line like above and float.

the line output is above

MCU output is above

TXS0108S input A2 is above, the resistor between the MCU and the 0108s is 100ohm.

So we remove the C1 D2 C2 outout line, the TXS0108 output become much better.below.

i have let the customer keep the line and remove the 0108s with three 0ohm resistor.

The waveform high frequency oscillation disapper too.

Do you have some ideas about the phenomenon?

Thanks.

BR

Frank

  • 0
    TI__Mastermind 24485 points
    Hello Frank,

    The TXS0108E is not going to be the right device for this application.
    Its likely that the passive output/low drive strength is causing an output oscillation when there is a capacitive load (ribbon cable) and it will likely be even worse when it is actually supposed to drive any current through an LED.

    A much better option for this application would be something like the SN74LV4T125.
    This device is a unidirectional buffer that can up translate from 3.3V to 5V and has significantly more drive strength than the passive translation from the TXS0108E device.

    I would recommned looking at this device:
    www.ti.com/.../sn74lv4t125

    Best,
    Michael