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TXB0304: OE pin and output pulse issue

David Zhao
Intellectual 1820 points
Part Number: TXB0304

Hi Supporter

My customer is adopting TXB0304. VCCA is 1.8V output and VCCB is 3.3V input. OE is connected to VCCA. Below CH3 is VCCB, CH1 is VCCA and CH2 is output. VCCA is power up first and then VCCB power up. When VCCB power up, a pulse comes up. If connected OE to VCCB, there is no such pulse. Please help with below two questions. Thanks a lot!

1.For this scenario, what the threshold of VCCB that will bring the output pulse?

2.Datasheet says OE need to connect to VCCA. Is it ok to connect OE to VCCB to remove this pulse?

Regards

David

  • 0
    TI__Guru 62200 points
    Hi David,

    sorry to hear this happen. I want to know what are the signal level at the IO pins at while this happens.
    Also, the OE pin is overvoltage tolerant which means that it can tolerate 3.3V while the Vcca is 1.8V and hence you can connect OE pin to Vccb without issue.
  • 0 in reply to ShreyasRao
    TI__Intellectual 1820 points
    Hi Shreyas

    Thanks for your response! While this pulse happens, input B IO is connected to GND, so the signal level is 0. Seems this pules is brought by VCCB power up. Please help analyze why this happens.

    Regards
    David
  • 0 in reply to David Zhao
    TI__Guru 62200 points
    David,

    Is there a possibility to ramp both the supplies simultaneously and see the response?
    What are the other 4 inputs at?
    This is something which is probably happening internal to the device and I could only think of mitigating this while I inform the team. I have also never come across this glitch situation before from any other customer ( as per the tracking system which started not too long ago).