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TMUX1072: RUTR

Hussain Y
Prodigy 25 points
Part Number: TMUX1072

Dear Team,

                         I am trying to control the ground of Multiplexer Tmux1072RUTR via transistor BC847B. I found some issue that , after some time the multiplexer goes into hang condition. In hang condition, the MUX IC is passes constant frequency, we are passing 40Mhz frequency from it . When the IC in hang condition , the frequency is was not change.

After reset the ground of MUX and power ON OFF of MUX the IC start work again.

I am attaching the schematic.

Regards,

Hussain

  • 0
    TI__Genius 10552 points

    Hi Hussain,

    Thanks for reaching out here. A few things to check here:

    1. Power Supply: Ensure the power supply to the MUX is stable and within the specified range
    2. Control Signals: Make sure the control signals to the MUX are stable and correct.
    3. Initialization Sequence: Review the initialization and power-up sequence. Incorrect sequence can lead to improper operation.

    If those check out as OK then please look at the transistor control - ensure the BC847B transistor controlling the ground of the MUX is operating correctly. If the transistor is not switching properly, it could affect the operation of the MUX which is likely what's happening here as this isn't typical behavior of the TMUX1072.

    Let me know if you can provide some scope shots as well if these tips don't help drive a resolution. 

    Regards,

    Alex

  • 0 in reply to Alex Vish
    Prodigy 25 points

    Hi Alex ,

                  I done all test. MUX power supply is stable and within the range. and i checked in scope also.

    Check all control signals.

    We are not switching the transistor always. Transistor is always in on condition.

    Also i just want to know, which is better for these purpose. Transistor or Mosfet.

    Regards,

    Hussain

  • 0 in reply to Hussain Y
    TI__Genius 10552 points

    Hi Hussain,

    So controlling the ground is a novel concept to me. I did some research and it looks like the hang up is due to the ESD diodes. There are ESD protection diodes on supply, I/O's and control pins of the device. So, if you disconnect any of the power pins, power will be supplied through the protection diodes which i believe is why you're seeing the hang-up. It's likely a MOSFET is the better solution to control the ground pin here. 

    Regards,

    Alex

  • 0 in reply to Alex Vish
    Prodigy 25 points

    Hi Alex,

       1-   I was also checked without ESD diodes, the MUX is going in hang up condition.

       2-  I haven't cut power supply of MUX ic. IC is automatically goes in hang up condition.

    Another question, which is better option to control power of IC is,Cut VCC path or ground path. 

    Regards,

    Hussain

  • 0 in reply to Hussain Y
    TI__Genius 10552 points

    Hi Hussain,

    Thanks for the feedback here. Typically to control the power of the IC is to control the VCC path. Like mentioned before, I haven't seen controlling ground as an alternative means to controlling the power to the IC before which is why I naturally lean towards the VCC path option here. 

    Regards,

    Alex