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SN74CB3Q3305: isolated input A and output B during start up, guaranty that the part is completely off no signal at B during Start up and when VCC is disable

Part Number: SN74CB3Q3305
Other Parts Discussed in Thread: SN74LVC2G66,

hi,

my customer would like to make sure that the switch is OFF during start up phase and when the Vcc is not applied.

we are looking on two part but if you think that there is a better part please let us know.

Input is 3.3V

signal A and B are used only for voltage measurement done by the CPU.

Parts that customer look at are the following:

SN74CB3Q3305 and SN74LVC2G66

THANKS..

  • Kamal,

    To ensure that the signal path is Hi-Z when Vcc = 0 V you need to find a switch that has this condition specified in the datasheet.  This spec is called by many different names: Ioff, powered off protection, Ipoweroff, ect but they all characterize the signal path leakage when Vcc = 0 V.

    The SN74CB3Q3305 device has this specification in the datasheet but the SN74LVC2G66 does not.

    You can search for all switches that have this powered off protection feature on our ti.com switch search tool.

    Thank you,

    Adam