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SN74LVC1G3157: Absolute maximum rating parameter definition

Part Number: SN74LVC1G3157
Other Parts Discussed in Thread: TMUX1072, TMUX154E

Hi,

I would like to double check the definition of VIN and VI/O, please help to confirm, thanks!

Thus, the VI/O is 5V and VCC is 3.3V, suppose this is over stress for SN74LVC1G3157.

Thanks and Best regards,

Tiger

  • Hi,

    It looks diagrams are not well uploaded, I attached again.

  • Hi Tiger,

    VCC is the supply voltage - this is the power supply for the IC. 

    Vin is the control voltage for the IC - this is where a digital signal will control the switch.

    V I/O  is the voltage at the I/O (a and b pins) w.r.t. ground. These pins have ESD protection diodes integrated into the IC. This is why you will see -0.5V min and a VCC + 0.5V max because neglecting these rating can cause the device to be damaged.

    As for your final question - yes if VI/O = 5V and VCC = 3.3V you are overstressing the device. We do have other 2:1 switches however that can support input voltages beyond the supply voltage - the caveat is that they are multi-channeled instead of single channel like this device. 

    Parts such as the TMUX1072 or TMUX154E can support 5V signaling when the VCC = 3.3V - these are two channel devices so one channel would be unused and can be left floating. There are also some other 4 channel solutions that may work as well and you can find the full list here

    If you have any other questions please let me know!

    Best,

    Parker Dodson

  • Hi Dodson,

    Thanks reply.

    We have a design miss,so if the VI/O=5V and VCC is 3.3V will overs-tress the device made the device quickly damage or maybe a few time(3 or  4 month or longer).

    BTW, we will correct the voltage level on DVT sample.

  • Hi Dylan.

    Yeah when the I/O voltage is > than VCC + 0.5 the ESD protection diodes starts conducting and that can cause a host of possible problems such as having current come out of the VCC pin, voltage overstress on the ESD protection diodes or current overstress from the overvoltage.

    However there is a work around. 

    If you add a current limiting resistor on the I/0 lines of the mux, when an overvoltage event occurs the current needs to be limited to < |50mA|. This can help prevent damage, but you won't pass higher than VCC. If you need to pass the entire voltage range up to 5V the VCC needs to be 5V - the parts I mentioned above can help if this is required for the application.

    If you have any other questions please let me know!

    Best,

    Parker Dodson