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SN74AHC125: SN74AHC125 used for extend SPI communication distance

Betty Guo
Expert 7300 points
Part Number: SN74AHC125

Hi

Can we use SN74AHC125 do  extend SPI communicating distance?

They use SPI to drive 8 cascades LED driver, the SLCK is 4MHz. Since the distance from MCU to the last LED driver is about 1.5 metre, the signals of SPI would be very poor, so, they want to add one SN74AHC125 before each LED driver. is this feasible? or do you have other good suggestions?

thanks,

  • 0
    Guru 243680 points
    Having a buffer every 20 cm should work fine. There will be a delay for each buffer, but it's not large enough to matter, and I guess there is no slave-to-master signal.

    Other methods to increase signal quality over long distances would be to use a single bus with higher voltage or differential signalling, but that would require driver and receiver chips at the master and at each slave, so no improvement over the AHC buffers.