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I am using the SPI interface to communicate with the MEMS sensor (ASM330LHH). My plan is to operate it at a 10 MHz speed.

The PCB is split into two parts, connected by cables. The distance between the processor board (TMS5703137CGWTQEP) and the sensor board is 2 inches.

Now, I have a question: How do I calculate the proper size resistor and capacitor for a snubber circuit for the clock and MOSI lines after the cable?”

Andy aka
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Priya
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  • Are you concerned about signal reflections on such a set-up? – Andy aka Mar 20 '24 at 14:01
  • @Colin it says on page 1 of the DS this: SPI & I²C host serial interface – Andy aka Mar 20 '24 at 14:04
  • The sensor has SPI interface. I will be using cable between sensor and processor board. Cables have high capacitance and may have additional impairments from the connectors. A snubber termination will probably be needed after the cable. – Priya Mar 20 '24 at 14:24
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    Over 2 inches? I don't think so. – Dave Tweed Mar 20 '24 at 14:31
  • @Colin It does have SPI. And many chips simply tell users to connect to a bus. They don't explicitly say users to connect to a bus which has been damped with snubber if it was ringing. – Justme Mar 20 '24 at 14:54
  • Please have a look at this link from TI forum where they had mentioned to have snubber circuit for spi lines (https://e2e.ti.com/support/processors-group/processors/f/processors-forum/332251/spi-clock-and-data-lines-routing-distribution-to-multiple-slaves) – Priya Mar 20 '24 at 15:28
  • @Priya That TI discussion is over an exotic application with over 50 distributed SPI nodes that require a complex fan out. You have 1 device 2 inches away. – MOSFET Mar 20 '24 at 21:13

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