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SN74LVC16T245: SN74LVC16T245 16-BIT DUAL-SUPPLY BUS TRANSCEIVER

Max Pom
Intellectual 330 points
Part Number: SN74LVC16T245
Other Parts Discussed in Thread: SN65LBC175, SN74LVC162244A, SN74LVCH162244A, SN74LVC16244A, SN74LVCH16244A, SN65LBC175A, SN74LVC244A

Hello,

Another question about SN74LVC16T245:

If VccA=3.3V, and the input is from a 5V device (VOH of this device is between 2.7 and 4.8V, that's why I didn't choose VccA=5V. If to be specific: SN65LBC175),

Is it tolerant to the 4.8V case?

(The absolute maximum rating says it's allowed to apply VccA + 0.5V to the OUTPUT, it means only if it used as an output?)

Thanks!

  • 0
    Guru 281470 points

    See the specifications for VI/O in the recommended operating conditions. (Which are not very clear; for an input, does "VCCO" mean the voltager of the other port?)

    Where do you get the 2.7 V from? The SN65LBC175 guarantees 3.5 V, and it has CMOS outputs, so when driving high-impedance CMOS inputs, the voltages will actually be at the rails (see figures 5 and 6 of the datasheet).

    Anyway, if the only purpose of the SN74LVC16T245 is to convert from a higher voltage to 3.3 V, then you can use any single-supply LVC buffer instead, because LVC has overvoltage-tolerant inputs. The SN74LVC16244A would be cheaper than the SN74LVC16T245, and the SN74LVC162244A has integrated series resistors. (And SN74LVCH16244A and SN74LVCH162244A have bus-hold inputs.)

  • 0 in reply to Clemens Ladisch
    Intellectual 330 points
    Yes, the only purpose is to convert the 5V output to 3.3V, and I meant the SN65LBC175A (with "A").
    So I undersand that if the VccA=3.3V, the device is not 5V-Tolerant, right?
    The SN74LVC244A is good for this purpose, right?
    Thanks!
  • 0 in reply to Max Pom
    Guru 281470 points
    The LBC175A outputs have the same CMOS structure, so they will be 5 V when driving CMOS inputs.

    LVC inputs are 5 V tolerant, LVC outputs are not. The LVC16T245 datasheet does not actually state whether the I/O pins behave the same when configured as inputs.

    In any case, the SN74LVC244A definitely works, and is simpler and cheaper.