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  • TI Thinks Resolved

TXB0104: there is no output on pins B if there are signals of input pins

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Replies: 12

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Part Number: TXB0104

Hi,

I try to make TXB0104PW works with 3.3V SPI from STM32 and 1.8V IMU ICM-20948 but without success. I've re-soldered pins  B1 - B4, provided input signals for A1-A4  (doesn't matter high, low or 50% duty pulses). there are no signals on output pins. 1.8 and 3.3 voltages are connected correct. Please see attached schematic. 

Thanks,
Vasyl

  • Yellow line A2 input, purple   B2 output.

    .

  • In reply to Vasyl Yosypenko:

    Hi,

    Based on the picture you gave, the TXB is connected correctly. But what are the lines connected to? If the output is being held low by another device, TXB does not have the drive strength to pull it up.

    What channel are you showing in the scope shot?

    Can you confirm that OE pin is at 1.8V at the pin?

    Thanks!

    -Karan

  • In reply to Karan Kotadia:

    "But what are the lines connected to? If the output is being held low by another device, TXB does not have the drive strength to pull it up."

    They were connected to  ICM-20948, but it didn't work. So I decided disconnect from this IC and try without it. There is no output signal in any cases.

    "What channel are you showing in the scope shot?"

    Output pins are disconected (left floating), yellow pin 3 (A2) - purple  pin 12 (B2).

    "Can you confirm that OE pin is at 1.8V at the pin?"

    yes

    I've tryed two ICs,but result is the same. Please see connection schematic for B output of level shifter.

  • In reply to Vasyl Yosypenko:

    Hi Vasyl,

    Thanks for confirming with initial questions from Karan.

    I see that the input is fine, and probing at the output without any IC should have shown some response. It is unlikely that 2 ICs you have tried would behave the same way. Please share the top side marking of the device, we can also look internally if there were any issues( unlikely).

    Is this on all the output pins or only on A2/ B2 channels?  Meanwhile, please show the Vcca, Vccb, and OE pins scope shots.

    -Thanks,

    Shreyas

    Watch the Introduction to AXC Family

    Read the app note on Glitch-free Power Sequencing for the AXC family

    Evaluate the AXC8T245 EVM and watch the translation using the EVM

  • In reply to ShreyasRao:

    I am also confused here. You have A2 (and Vcca ) at 1.8V level, but the scopeshot shows 3.3V input? Please confirm.

    and please put the trigger level below 1.8V and on the output channel.

    -Thanks,

    Shreyas

    Watch the Introduction to AXC Family

    Read the app note on Glitch-free Power Sequencing for the AXC family

    Evaluate the AXC8T245 EVM and watch the translation using the EVM

  • In reply to ShreyasRao:

    Hi Shreyas, 


    thank you for fast responce. Tomorrow I'will attached scope shots that you require. And photo of the top of ICs.

    Thanks,

    Vasyl

  • In reply to ShreyasRao:

    "I am also confused here. You have A2 (and Vcca ) at 1.8V level, but the scopeshot shows 3.3V input? Please confirm."

    you are right. scope picture is correct but my description is wrong. Input is B2, and output is A2. 

    Thanks,

    Vasyl

  • In reply to Vasyl Yosypenko:

    "Please share the top side marking of the device, we can also look internally if there were any issues( unlikely)."

    Please see attached picture.

    Is this on all the output pins or only on A2/ B2 channels?  

    The same situation for all pins, no output even there are signals on input pins.

  • In reply to Vasyl Yosypenko:

    "Meanwhile, please show the Vcca, Vccb, "

    yellow VCCA - 1.8, purple VCCB- 3.3V 

    yellow - B2 (input), purple - OE.

  • In reply to Vasyl Yosypenko:

    Vasyl,

    The Vcc pins looks good. In your board photo, what is that paper which seems to be in the within the device pins? 

    I dont see other issues on the schematics or the scopeshots. Anything w.r.t the trigger set to 1.5V on the A channels? 

    Would you happen to have another set of devices(not from the same lot/ reel) which you could try out? 

    -Thanks,

    Shreyas

    Watch the Introduction to AXC Family

    Read the app note on Glitch-free Power Sequencing for the AXC family

    Evaluate the AXC8T245 EVM and watch the translation using the EVM

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