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SN74LVC2G66: Reverse Current when VCC=0

Saminah C
Genius 9132 points
Part Number: SN74LVC2G66
Other Parts Discussed in Thread: TS5A23166

Hi,

Will there be reverse current when the VCC is 0V in SN74LVC2G66?

My test result from the lab shows that some times side B will short and some times doesn’t.

May I confirm with you if this will happens if there are no VCC?

 

 

 We are unable to know if there will be issues when 3.3V is at side B and there is no VCC.

  • 0
    TI__Expert 5660 points

    Hello,

    It sounds like you are asking about powered-off protection. Here is a great E2E post that describes powered-off protection.  A TI switch with powered-off protection will maintain a high impedance state on the I/O and digital pins (no reverse current) when the switch's supply is not powered (VCC = 0 V).

    SN74LVC2G66 does not have powered-off protection, so the internal ESD diodes will be forward biased when VI/O exceeds VCC.

    TI has many switches with powered-off protection. You can use the online product search tool to select a switch based on configuration, channels, and features, such as powered-off protection. I found TS5A23166, a 2-channel, 2:1 switch, which will be able to maintain the high impedance state when VCC = 0V, protecting your signal path and system. I recommend replacing SN74LVC2G66 with TS5A23166 if you expect a signal to be present at the I/O when VCC = 0V.

    Best regards,

    Kate