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SPI in rough environment with transients

F.E. Brand
Prodigy 30 points
Other Parts Discussed in Thread: LM306, UCC27517, TLV1805, SN65LVDT41, AM26LV31

Hi,

we are using a SPI-transmission in a rough environment with random transient fields, which are  sometimes disturb the transmission.

The idea is to shift the levels from 3V3 to 12V (or more) that the induced transients (in a range of 4V)  will not be seen as HIGH-level.

We know (old) circuits like CD40109, but they are not fast enough for SPI.  Existing SPI-Shifters end up at 5V.

Are there other components or ideas ?

regards, E. Brand

  • 0
    Guru 257340 points

    To translate fast signals to higher voltages, you can use gate drivers like the UCC27517. To translate them down, you can use any fast, high-voltage comparator like the TLV1805 or LM306.

    However, using higher voltages gives only limited protection. A much better solution would be differential transmission, with two lines per signals. There are specialized SPI transceivers like the SN65LVDT41/14, but you can also use plain LVDS transmitters/receivers. In very rough environments, you could also use RS-422/RS-485 transceivers like the AM26LV31/32.