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SN74CBT3384A: CBT vs. CB3T for translating 5V to 3,3V (bi-directional).

Part Number: SN74CBT3384A
Other Parts Discussed in Thread: SN74AVC16T245

Having read several documents like e.g. "CBT-C, CB3T, and CB3Q Signal-Switch Families"

I'm still unsure whether to use a CB3T or CBT device for translating bi-drectional FPGA signals (3,3V) to a

5Volt system. Right now I'd prefer use a SN74CBT3384A as it is specified for up to 200MHz and seems to be


Any pointers/insights would be highly appreciated!

  • User5112991,

    What is the reason you are wanting to use a switch for level shifting instead of a level shifter like the SN74AVC16T245 device?

    The level shifter solution cost should be lower since you won't have to worry about the board space, BOM, and routing of using a signal switch with 2 pull up resistors on every channel.

    Thank you,
  • As I understand the AVC-family is only 4,6Volt tolerant... I want to use an FPGA in a 5Volt environment.

  • Dear Adam,

    just as an additional note I'd like to point to this TI document:



    So the question remains when to chose CB3T over CBT device for usage in level-switch applications.



  • Frank,

    Both the CBT and CB3T devices can be used for level shifting applications.  The CBT device operates with a 5V supply and CB3T operates with a 3V supply.  This reason to choose the difference between the two families for level shifting applications depends on the voltage domains you have in your system.

    Thank you,