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Voltage Translator Bandwidth and Data Rate Problem

Soner Isiksal
Prodigy 55 points
Other Parts Discussed in Thread: SN74AVCB164245-EP

Hi,

Frequency vs. gain curve are given for some of your voltage translator products and it is easy to see the -3dB cut-off frequency from the graph. Then I can decide the maximum data rate by dividing 2,3,5 or whichever harmonics I need. 

However, in most of your products this graph is not given. BW can also be acquired from rise/fall times by 0.35/tr (for 10%-90%) but this data is also not provided. Though propogation delay for both high to low and low to high states are always given, BW should not be a function of tpd. 

When I list all the products in the main product search page, a column giving info about data rates appears but how can I trust this data? I think those are not empirical as datasheets may not include them. 

Short Question: How can I estimate data rate without knowing neiter -3dB cutoff frequency nor rise/fall time.

Regards,

  • 0
    TI__Expert 6430 points

    Hi Soner,

    Thanks for your feedback.  There are missing data rate parameter in some device datasheet.

    In general, SN74AVC/LVC XX serials parts can support more than 100Mbps data rate , TXB serial can support less than 100Mbps data rate and TXS can support less than 25Mbps. 

    However, for tranlation device, the data rate will depend on input driver and output load. If input driver is weak  or output load is larger, the date rate will decrease.

    If you want to use TI device in your system and device parametersare not clear, please post the detail applcation information, we will give the feedback on time.

    Thanks

     

  • 0 in reply to Wei Lang
    Prodigy 55 points

    Thank you for your reply, 

    Generalisations about families are okay, but >100Mbps or <25 is not sufficient. How much big or small? Moreover, there are TXB-family products claiming >100Mbps data rate for instance. Generalisations may fail. Tthere are other families as well.

    I just need to know how to calculate it. 

    I'm reducing my question to a single case:

    How can I estimate the maximum data rate per channel for the following product by just checking the datasheet (with arbitrary Va,Vb or Cl etc.): http://www.ti.com/lit/ds/symlink/sn74avcb164245-ep.pdf

    What I need is not just a value like 300M, I am just trying to find out the method. There must be an explicit way.

    I would be greatful if you can help me,  

    Thanks,