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

user5112991
Prodigy 30 points
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

cheaper....

Any pointers/insights would be highly appreciated!

  • 0
    TI__Mastermind 45410 points
    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,
    Adam
  • 0 in reply to Adam Torma
    Prodigy 30 points

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

  • 0 in reply to Adam Torma
    Prodigy 30 points

    Dear Adam,

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

    SCDA006

    hxxp://www.ti.com/lit/an/scda006/scda006.pdf

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

    Thanks,

    Frank

  • 0 in reply to user5112991
    TI__Mastermind 45410 points

    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,

    Adam