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TS3A27518E: Input Voltage and VCC voltage

Jerry%20Leung
Intellectual 905 points
Part Number: TS3A27518E
Other Parts Discussed in Thread: TMUX1072, SN74CB3Q3257

Hi Team,

Just want to quickly verify for a customer, if we have VCC of 3.0V and one of the input is having a voltage of 3.3V, will the device clamp the signal to 3.0V ?

Thanks and best,

Jerry

  • 0
    TI__Mastermind 45340 points

    Jerry,

    Operating the TS3A27518E device with Vcc = 3.0V and having a signal of 3.3 V on the I/O signal path will violate the recommended operating conditions in the datasheet.

    This abs max table shows that there is not a protection diode path from I/O signal path to Vcc.  The spec would read Vcc +0.5 V if there was a clamp diode present.   This means the TS3A27518E signal path will not clamp the voltage when the voltage on the I/O path is greater than Vcc.  There is risk of reliability and damage to the device operating outside of the recommended operating conditions.

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    TI__Intellectual 905 points

    Hi Adam,

    Thanks and appreciate the clarification here. So in this case, would a device such as the TMUX1072 work? I see that it doesn't specify operating to VCC in the recommended operating conditions. If so, would you know of any with higher channel count?

    Thanks for the help!

    Best,

    Jerry

  • 0 in reply to Jerry%20Leung
    TI__Mastermind 45340 points
    Jerry,

    Yes, devices like the TMUX1072 that don't specify Vcc as the max I/O voltage can have signals exceed the supply voltage.

    What do you think about the SN74CB3Q3257?

    What are you connecting to the switch that needs voltages that exceed the supply rail?

    Adam
  • 0 in reply to Adam Torma
    TI__Intellectual 905 points

    Hi Adam,

    I see thanks for the confirmation,  looks like the customer wants to level shift the signal, I will look into some bidirectional voltage translators to recommend. 

    Just a quick sanity check question back on the TS3A27518E, if the analog input voltage exceeds to 3.3V when the switch is NOT enabled but with VCC=3.0V, would it still be fine and the reliability won't be affected right? 

    Thanks and best,

    Jerry

  • 0 in reply to Jerry%20Leung
    TI__Mastermind 45340 points
    Jerry,

    The TS3A27518E recommended operating condition for analog input voltage is 0 to Vcc. In a system where Vcc = 3.0V and any analog input > 3.0V will be outside the recommended operating conditions. This specification is valid for both enabled and not enabled cases.

    Thank you,
    Adam