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Original question:

TS3A5223: Upper voltage tolerance of NC1, NC2, NO1, NO2, COM1 and COM2

TS3A5223: Damage if NO/NC/COM higher than VCC

Jim Perkins
Expert 3570 points
Part Number: TS3A5223
Other Parts Discussed in Thread: TS5A23159,

For TS3A5223 (and TS5A23159), what happens in NC/NO/COM have voltages applied before VCC is present?  I understand this can cause the internal ESD diodes to conduct but what is the consequence of this?  Is it undetermined behaviour, leakage, permanent damage, destruction etc?

Thanks

Jim

  • +1
    Guru 316690 points

    A current will flow from the I/O pin into VCC, and might partially power up all devices connected to this supply.

    If the current is not limited, it might exceed the absolute maximum rating of 50 mA (it's specified only for the TS5A23159; for the TS3A5223, it might be lower) and damage the device.

  • 0
    TI__Genius 10552 points

    Hi Jim,

    The team is currently on holiday. Please allow until Monday next week for a response here. 

    Regards,

    Alex

  • +1
    TI__Genius 10552 points

    Hi Jim,

    Applying voltages to NC/NO/COM pins before proper VCC levels are present can indeed cause permanent damage or signal integrity issues - as well as powering of downstream devices. The extent of which will vary based on voltage levels applied before VCC is present and the duration of said signal. As Clemens mentioned, damage will occur if current isn't limited. Of course, if the output of the device still works for your application in this fashion, then that's great. TI can't guarantee performance in this instance though, as that is not the recommended implementation of these devices. 

    Let me know if you need anything else here. 

    Thanks!

    Alex