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LM25066: LM25066 SMBus/IIC and level translation

Joe Miller
Prodigy 160 points
Part Number: LM25066
Other Parts Discussed in Thread: TXS0102, LSF0102, ,

Dear Sir/Madam,

For SDA/SCL what level translator is suitable for translation from +1V8 (host) to +3V3 (LM25066)?
On a previous product with +3V3 (host) to +3V3 (LM25066) the SDA/SCL pull-up resistors needed to be no greater than 4K7
for suitable rise time.

Also is SMBAn open drain? Can this pin be connected to a 2K pull-up to +1V8?

Regards Joe

  • 0
    TI__Genius 12621 points

    Hey Joe,

    Welcome to the E2E forums!

    For level translators, you would probably need a bidirectional translator from this page:
    www.ti.com/.../bidirectional-voltage-translation-products.page

    Our team supporting the LM25066 have not tested different I2C translators. Our understanding is that the TXB01x series would not be suitable for I2C/SMBus/PMBus whereas the TXS01x or LSF01x series would be.

    Since the SMBA is already an open drain output, I believe you would only need two channels and so a device like the TXS0102 or LSF0102 may be suitable.
    www.ti.com/.../txs0102.pdf
    www.ti.com/.../lsf0102.pdf

    However, I would encourage you to post an E2E question about the TXS0102 or LSF0102 so the team supporting those devices can assist you.

    FYI - the LM25066 datasheet has most of the updated content whereas LM25066A and LM25066IA datasheets may be missing some additional words.

    The LM25066 specifies the SMBA is an open drain output on its pin descriptions table on page 4:
    www.ti.com/.../lm25066.pdf

    Thanks!
    Alex

    Edit: FYI - I grabbed the LSX0102 part number based on this voltage level translator selection guide:

    http://www.ti.com/lit/ml/scyb018h/scyb018h.pdf