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TXB0108: TXB, TXS & LSF family (Part 2)

lee peng kiat
Intellectual 450 points
Part Number: TXB0108
Other Parts Discussed in Thread: TXB0304, SN74AXC4T774

Dear Sir/Madam,

will it cause internal chipset crosstalk problem when difference high speed signals are connected to single voltage level shifter ?

For example the I2S & SPI signals connected to single 8 bit voltage level shifter (TXB, TXS or LSF family),  Is there any possibility for these two signals create internal chipset crosstalk to each other ?

Thanks.

  • 0
    TI__Mastermind 45835 points

    Hey Lee,

    I would say the worst case scenario for cross talk would be random bit streams with different frequencies on each channel so its definitely a possibility. I don't think it should be a huge concern with these types of devices having weaker drivers, and I would  say the LSF family would have the least amount due to not having the edge-rate acceleration circuitry seen in both the TXB and TXS families.

  • 0 in reply to Dylan Hubbard
    Intellectual 450 points

    Hi Dylan Hubbard,

    Thanks for detail explanation.

    Base on datasheet of TXS & TXB family,  both family using the same load ( C= 15pF, R=1M ohm)  to do the measurement for max data rate.

    With the same condition (VCCA =1.8V, VCCB = 3.3V) for both TXS & TXB family,  the result of max data rate is 70Mbps & 60Mbps respectively.

    1)   That means TXS family is more suitable for high speed signal if compare to TXB family ?

    2)    May I know why the max data rate measurement test need to used this load ( C= 15pF, R=1M ohm) ?

    3)    I going to used it for I2S signal which max CLK frequency can reach up to  26MHz, does these two family suitable for this application ?

    Thanks

  • 0 in reply to lee peng kiat
    TI__Mastermind 45835 points

    Hey Lee,

    1) Based on the two values you provided, yes. If you only need 4 channels then I would say the TXB0304 would be the best in this category.

    2) This is to simulate something close to what a designer would have in their system. It basically simulates another CMOS input with its input capacitance + trace capacitance and High impedance. Heavier capacitive loads will results in lower data rates.

    3) Either should work, but I would actually recommend the SN74AXC4T774 device for this.