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Original question:

Searching footprint compatible LVT Alternative for Little-Logic Device 74LVC2G241DCT (which is in a 8-Pin SM8 DCT Package...

SN74AXCH8T245: Any Solution for Dual Supply Direction Controlled Voltage Translation (Substitution of high current driver 74LVTH245) ?

Karlheinz Kaiser
Prodigy 40 points
Part Number: SN74AXCH8T245
Other Parts Discussed in Thread: SN74LVCH8T245

Hello,

For new FPGA technologies such as Intel ARRIA10, it is recommended to operate FPGA-IOs  in a 3.0 V environment.

Are there solutions for connecting a  medium size parallel bus system to such 3V FPGAs.

Up to now  we use  the 74LVTH245 (which is able to drive low Level currents of 64mA@0.55V ) for interfacing it to an 3.3V FPGA

For a new ARRIA 10 design we  need to rework the Interfaces.

It would be nice to find a Dual Supply / Direction controlled Level Translator like the  74LVTH2240WM  with higher current  driving capabilities  on the market.

There is no Chance to drive a medium size bus system with IOL max 12mA  (from  74LVTH2240WM data sheet) .

Are there any plans from TI  or ideas to match this requirement ?

  • 0
    TI__Mastermind 24485 points

    Hello Karlheinz,

    If I understand correctly, you used a previous device that can drive up to 64mA/channel, but now you need a high current drive solution with level translating as well.

    Does the SN74AXCH8T245 meet the requirements of your system? 

    While the channels are specified to 12mA to provide a particular VOH/VOL voltage, the channels are capable of driving higher currents as long as the VOH/VOL levels are acceptable for your system.
    Additionally, you could parallel output channels to increase current drive to meet your system requirements, is this a possibility?

    How many lines do you need to drive? Are these signals all single direction? Is there a particular interface you are planning on using?

    Another option that may work for you would be the SN74LVCH8T245 device which is specified up to 24mA/channel at 3V. Again in this case, the channels are capable of driving higher currents and channels can be paralleled to increase drive strength.

    Hope this helps! 
    Please let me know what additional questions you might have as well.
    Michael

  • 0 in reply to Michael J Schultis
    Prodigy 40 points
    Hello Michael

    Thanks for your quick reply.

    a)Our uni-directional Outputs (Address, Clock, Board Select and R/W Control ) can be let "as is" with 74LVTH245.
    b)Our uni-directional Inputs (Interrupt lines) need level shifting.
    c)Our bi-directional data bus needs Level shifting and direction control

    Tristate ability on (b) and (c) would be nice for proper power-up sequencing of the ARRIA.

    Therefore we should have a closer look to the SN74LVCH8T245.

    In the past, we had most trouble with ugly reflections on the bus clock line on different bus slots when using one 74LVC2G241 (specified to 24mA @ 0.55V)

    Whilst using three 74LCV2G241 in parallel ( or one 74LVTH245) no bus Errors occurred any more, even in long-time tests.

    So sufficient driveability almost helped for critical bus lines. Best experience we had with the 74LVTH245.