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TS3A5018: About absolutely maximum rating, i can't find the requirement about Analog voltage compare to the power supply.

user1441377
Prodigy 60 points
Part Number: TS3A5018
Other Parts Discussed in Thread: TMUX1574

Hello,

In my application of TS3A5018, because the power supply and analog voltage are drived by different power railed, so is there any requirement between Analog voltage compare to the power supply.

When I power off my PCBA, because the damp rate are different, one NC pin(below pink trace)  will higher than power supply(below orange trace) about 0.5V, with  5ms time. Will this damage the chip?

I am afraid of  the latch up risky.

Thank you!

  • 0
    TI__Genius 9132 points

    Hi,

    You can find this information in the recommended operating conditions.

    The TS3A5018 can support input voltage up to the supply and the supply range is from 1.65V to 3.6V.

    The TS3A5018  datasheet states you can place a voltage from 0 to 3.6 V on the Vcom pin while V+ = 0V.  This device isolation capability in this condition is a leakage up to 2 uA.  


    I would recommend the TMUX1574 in similar configuration to the TS3A5018. The TMUX1574 supports input voltage beyond supply, offers a higher bandwidth, lower Ron, powered-off protection (provides isolation when the supply voltage is removed (VDD = 0 V), and 1.8V logic compatible control pins. The device comparison table is shown below:

    Regards,

    Saminah

  • 0
    Prodigy 60 points

    Hello, thanks for your kindly responds.

    But my question is still not resolved.

    I know the absolutely maximum rating for analog input and power supply in the datasheet. But what I need is whether there is additional requirement for the voltage difference between them?

    Please help to review my oscilloscope trace, I am worried about it will cause latch up and damage the chip.

  • 0 in reply to user1441377
    Guru 269710 points

    All voltages in the datasheet are measured relative to GND. So if the voltage difference between an analog input and GND is larger than the voltage difference between V+ and GND, then you are outside the recommended operating conditions.

    The TS3A5018 datasheet says that the absolute maximum rating for the analog pins is 4.6 V, so going 0.5 V above V+ will not damage the device.

  • 0 in reply to Clemens Ladisch
    Prodigy 60 points

    Hi Clemens,

    Thanks for your reply, I agree your comment.

    Since my failed is related to field damage, my customer still need I got the official replay from TI.

  • 0 in reply to Saminah C
    Prodigy 60 points

    Hi Saminah,

    Since my failed is related to field damage, my customer still need I got the official reply from TI.

    Could you please help to conform: whether the osciloscope trace I paste have risk?

    One NC pin(below pink trace)  will higher than power supply(below orange trace) about 0.5V, with  5ms time. Will this damage the chip?

  • 0 in reply to user1441377
    TI__Genius 9132 points

    Hi,

    Looking at the waveform, this should not cause issue since you are seeing it for a short duration. Can you also measure the current and make sure it is not exceeding 50mA?

    See the note below the Absolute Maximum ratings table "The input and output voltage ratings may be exceeded if the input and output clamp-current ratings are observed".

    Thanks

    Saminah

  • 0 in reply to Saminah C
    Prodigy 60 points

    Hi Saminah,

    Thanks for your kindly reply, I test the current as below figures.

    I test the current in power off period, it is not beyond +/-10 mA.

    Do you think my test is sufficient to believe my application would not damage the chip in this power off period? Thank you!

    Test point is below:

    Below is the normal operation trace, the current peak is within +/-30mA.

    Below is the test record when power off the PCBA. The peak current IS NOT beyond +/-10mA,may be it is only test noise.

  • 0 in reply to user1441377
    TI__Genius 9132 points

    Hi,

    You should be ok.

    We would recommend keeping maximum current below 30mA just to have a little bit of buffer and I see that's what you are measuring under normal operation.

    You can also add  series resistance to help protect inputs from over-voltage events. 

    Thanks

    Saminah