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SN74LVC4245A: SN74LVC4245A

Alex Boulahia
Prodigy 50 points
Part Number: SN74LVC4245A
Other Parts Discussed in Thread: SN74AXC8T245

I am trying to find a bus transceiver to connect the STM32 ARM processor which operate at 3.3V to some DACs and ADCs that operate at 5V, asynchronous operation SPI bus.

I saw the SN74LVC4245A and thought that looks good, when i read the data sheet and the associated technical document i got even more confused.

issues such as the power up sequence, the need to tie the OE signal high (i wanted to connect it low at all time), and the high Z state (which i don't know why i need, is the high Z state only during power up ?).

i really need someone to explain to me if i am making the right choice or not 

Alex.

  • 0
    TI__Guru 54666 points

    Hi Alex,

    The power up recommendation should be considered mainly if you care about the state of the I/O during power up.

    I.e when OE| is low, the outputs will always be enabled. Hence, when output is enabled with VCC / inputs not fully ramped; the outputs may observe an unknown state until fully ramped up.

    You may also see SN74AXC8T245 with a more robust power sequence, thanks.

    Best Regards,

    Michael.

  • 0 in reply to Michael Ikwuyum
    Prodigy 50 points

    Hi Michael,

    Thank you for the explanation, i am happy to use the SN74LVC4245A, the power up sequence is not important in this application.

    Just another question i looked at the SN74AXC8T245 and it only handles voltages up to 3.6V (designed for 1.8V to 3.6V in the specs), i need to convert 3.3V from the STM32 ARM processor to 5V DACs and ADCs, my question is the SN74LVC8T245 its equivalent for 3.3V to 5V ?.

    Kind regards.

    Alex.

  • +1 in reply to Alex Boulahia
    TI__Guru 54666 points

    Hi Alex,

    Glad it works for you. And apologies for the typo as LXC was the intended recommendation, i.e SN74LXC8T245 (with a more robust power sequence as well) is the SN74LVC8T245 equivalent for 3.3V to 5V, thanks.

    Best Regards,

    Michael.