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SN74LVTH244A: Alternative with slower slew rate

Marvin Gasis Arcangel
Genius 9915 points
Part Number: SN74LVTH244A

Hi Team,

Can you help with the inquiry below?

We previously had FPGA driving input to solid state relay, all in 5V logic. FPGA outputs were slew rate limited. Needing to replace FPGA due to DMS, but now 3.3V logic. Still interfaces with the same solid-state relay so needs 3.3V to 5V level translation. Would like to maintain a similar slew rate limit. Unfortunately, FPGA does not specify slew rate, just total propagation delay for slow slew rate versus fast slew rate (approx. 2 ns difference). We are looking for a part similar to SN74LVTH244.

Thank you in advance.

Regards,

Marvin

  • 0
    TI__Guru* 96681 points

    Hi Marvin,

    Most logic is intended to produce very fast output signals. The AUP logic family has slower transitioning outputs that some of our customers use for EMI reduction, but we don't specify a slew rate or have any specific slew-rate limited logic gates in our portfolio.

    They could try using a logic family with less drive strength - for example, the HC logic family typically has outputs around 30 ohms at 5V, while the SN74LVTH244A has outputs closer to 5 ohms.

    I would recommend just picking up a few pin to pin options and trying them in their system -- all the '244 functions will have the same pinout. I can't directly link to a pre-filtered list of only '244 functions, but you can easily go to the link below and enter "244" in the filter box at the top of the parametrics table.

    https://www.ti.com/logic-voltage-translation/buffers-drivers-transceivers/noninverting/products.html

    They can try sorting by I_OL or I_OH and look for devices with less drive strength to get slower slew rates.