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TMUX1309: Input tolerant, Sx = 3.3V at Vdd=0V

Yusuke Mukuno
Expert 7395 points
Part Number: TMUX1309

Hi expert,

My customer is considering TMUX1309. however their system has the condition that is supplied 3.3V to Sx at Vdd=0V. 

ABS max for Sx pins is Vdd+0.5V.

Will TMUX1309 have any damage with this condition?

I found the diode between Sx pin and Vdd pin in Figure 8-14. I believe the ABS max value come from Vf of this diode.

Customer can accept Sx pin series resistor for limiting current.

If we can provide the acceptable current for diode, can the customer use this device with this condition?

Thanks

Muk

  • 0
    TI__Mastermind 46687 points

    Hi Muk,

    Figure 8-14 is showing how typical CMOS switches are constructed - the TMUX13xx family does not have a diode from I/O to VDD. 

    The Abs. Max Ratings seem to have an error - as this part can handle the exact scenario you are talking about - when the proper precautions are taken.

    See below for the application use case you have described:

    Essentially there are no back-powering diodes - which are usually the issue with overvolting inputs like this. All that needs to be done is add a current limiting resistor in front of the input that will be overvolted. As the injection current control will shunt the I/O to GND when it is overvolted. The part can handle 50mA of injection current into any 1 pin but it can only take a combination of 100mA at any one time. For best results if the current can be <1mA the better the part will perform, so if the application allows a 3K resistor or larger will give the best results. There will be voltage coupling the output but it should remain < 400mV. 

    Please let me know if you have any other questions. 

    Best,

    Parker Dodson