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TXB0304: Real maximum frequency

Juan Abelaira76
Prodigy 60 points
Part Number: TXB0304
Other Parts Discussed in Thread: TXB0302, TXB0106, LSF0108

I'm thinking of using TXB0304 plus TXB0302 to translate QSPI signals (clock plus DQ0...DQ3) from 1V5 (host, an FPGA) to 3V3 (could be 2V5 or 1V8 if that helps)

Datasheet mentions some maximum data rates but I think that's for individual signals. Synchronous data are affected by the delay difference that happens to be significant and I suppose it adds up to each signal degradation. On top of that I will be using more than one device as I have 5 signals and I'm concerned about the device to device variation as well.

How reliable is it to use those devices for QSPI? Ideally I'd be running them at >100 MHz but it can be acceptable at 50, even 40 MHz

  • 0
    TI__Guru 56070 points
    Juan,

    As you have noted, the max data rates given on the datasheet cannot support 100Mhz data. The data rates also consider single channel at a time and not all channels switching.
    I have come across the QSPI interface and I usually suggest using the TXB0106 ( 6 channel auto bidirectional) device for it. however, the TXB0106 doesn't support high datarate as per your requirement.
    The lower the cap loading, the possibility of higher data rate to acheive higher data rate.
    The datasheet mentions the channel to channel skew, but we do not guarantee the process skew or the device to device tpd variation.
    The other device which you could consider is the LSF0108( 8 channel auto BD translator). This uses external pullup resistors which can be selected as per the design requirements ( external cap loads, host drive stregth etc). The restriction on this device is that the Vccb must be atleast 0.8V higher than Vcca; which may not work for the 1.5 to 1.8V translation.
    you can watch the videos on LSF operation here:
    training.ti.com/tlm-lsf-basics
    or the FAQ here:
    e2e.ti.com/.../742100