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SN74GTL2003: SN74GTL2003 between LVCMOS18(1.8V) and LVTTL 3.3V

Young Geun You
Prodigy 20 points
Part Number: SN74GTL2003
Other Parts Discussed in Thread: SN74AXC8T245

I have some questions about sn74gtl2003.

1. I want to translate from LVCMOS18(1.8V, Source of SN74GTL2003) ports to 3.3 LVTTL(3.3V, Drain of SN74GTL2003).

   Is this possible? does SN74GTL2003 support LVCMOS18??

2. If I want to set LVCMOS18 ports as unidirectional input(Source of SN74GTL2003), do I have to connect pull-up resistors with 3.3V LVTTL ports(Output, Drain of SN74GTL2003))??

    And also, upside down, If I want to set LVCMOS18 ports as unidirectional output(Source of SN74GTL2003), I do not need pull-up resistors with 3.3V LVTTL ports(Input, Drain of SN74GTL2003))??

    Are these correct connection?

  • 0
    TI__Guru 59760 points
    Hi Young,

    To your specific questions,
    1) Yes, you can do 1.8 to 3.3V
    2) Input push pull to the GTL would not require the pull-up resistor, but you need pull-up resistors for the output.
    3) For better signal integrity, the 1.8V output would require pull-up resistors as well. Even if you do not have, the output will clamp to 1.8V, but can drop when the output is loaded. The input would not require pull-up resistors.

    Would you consider using DIR controlled devices like the SN74AXC8T245 which has 1.8 to 3.3V bidirectional translation support. You do not need external pull-up resistors for the DIR controlled devices.