• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 15 subscribers
  • Views 369 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TMUX1309: Confirm if the design is reliable for continuous operation

Jonathan Geronga
Expert 7930 points
Part Number: TMUX1309
Other Parts Discussed in Thread: TMUX1308

Hi Team,

I would like to get your help in confirming the customer design below for TMUX1309.


The customer has 8 voltages to measure using TMUX1309. They are around 30V.
All 30 V sources are with respect to Gnd which has the same potential with Vssa
In order not to repeat the same resistive voltage divider circuit. They have an idea to place the lower resistor to the output of TMUX and using only high side resistors at the inputs

Is this solution reliable for continuous operation?

The customer needs 10 samples per second
The ADC is one of TMS32F280049 ADC channels

Please let me know if you have any questions to confirm the customer design.

Thanks,

Jonathan

  • 0
    TI__Intellectual 2694 points

    Hi Jonathan,

    Thank you for reaching out. 

    The functional use of the 8:1 Mux to sample the 8 input signals one at a time looks good as it will save lot of component space/cost. They need to account for the switch RON/RDSon resistance in the calculation which is very small factor but definitely exists and get's added to the high side resistor.

    Couple of concerns to highlight in the schematic.

    - The TMUX1309 is not a 8:1 Mux. It is a 2ch, 4:1 Mux. TMUX1308 is 8:1 Mux. See datasheet here https://www.ti.com/lit/ds/symlink/tmux1309.pdf.

    - The TMUX1308/9 is a low voltage device and supports 1.62V to 5.5V supply operation. Since this is a rail to rail device, the signal allowed on Sx or D pins are between 0V to VDD.

    - Since the customer wants to sample 30V, I would recommend one of our mid-voltage 8:1 Mux device - TMUX6208PWR as this device supports 4.5V to 36V Single supply operation and the signal allowed is 0V to VDD in Single supply mode or (+/-4.5V to +/-18V supply, VSS to VDD in Dual supply mode). Datasheet - https://www.ti.com/lit/ds/symlink/tmux6208.pdf

    - if they need small footprint now, another option is MUX36S08IRUMR. This device supports 10V to 36V single rail supply operation ( 0V to VDD signal). Datasheet - https://www.ti.com/lit/ds/symlink/mux36s08.pdf 

     

    Question:

    - What is the available VDDA rail voltage? 

    - Please confirm that they are sampling 30V signals.

    - Where is A0/A1/A2 and EN coming from as these signal control the channel selection and chip enable/disable.

    Thank you,

    Sandesh

    .

  • 0
    TI__Intellectual 2694 points

    HI Jonathan,

    Please let us know if any help needed on this topic.

    Regards,
    Sandesh

  • 0 in reply to Sandesh Rawool
    TI__Expert 7930 points

    Hi Sandesh,

    I did not anymore receive a response to this inquiry.
    We can now close this thread.

    Thank you for your kind support.

    Regards,

    Jonathan