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Original question:

P82B96: Design help and clarification

P82B96: LVDS for transmitting I2C in noisy environment

Neet
Intellectual 281 points
Part Number: P82B96
Other Parts Discussed in Thread: TIDA-060013, P82B715

Dear community,

We are currently working on a condition-monitoring system that involves interfacing multiple I2C and SPI sensors to an MCU in a noisy industrial environment. We have come across the TIDA-060013 reference design, where the designers have successfully connected the B-side of the P82B96 with a CAN transceiver.

We are considering the possibility of replacing the CAN transceiver with LVDS, specifically the DLVDS047, as we are already planning to use the DLVDS047/48 pair for one of our existing SPI lines. Our main concern is whether there are any fundamental issues or potential errors in using the combination of P82B96 and DLVDS047 to achieve better noise immunity in an industrial environment.

Here are the design specifications for our system:

Communication speed: 400kHz
Maximum distance: >5m
Configuration: 1 slave (sensor) to 1 master (MCU)
4 I2C lines, all using the same configuration
P82B96 will be used to convert bidirectional signals into unidirectional signals
We aim to keep the cost of the system as low as possible while prioritizing maximum data integrity in the suggested configuration. Therefore, we kindly request suggestions for cost-optimized options that can ensure reliable data transmission.

Furthermore, we are interested in exploring the feasibility of transmitting the B-side signals over STP cables (24AWG Cat5) without the need for any differential transceivers. We have observed a similar implementation using P82B715 and would appreciate insights on whether this approach is viable for our system.

We sincerely appreciate any insights, advice, or recommendations you can provide.

Thank you in advance.

  • +1
    Guru 224380 points

    If LVDS already works for SPI, then you can also use it for I²C. (The I²C clock is not any more sensitive to noise than the SPI clock.)

    It is possible to use the P82B715 for I²C. In that case, you are relying only on the large currents to avoid noise. This is less effective than differential transmission; whether this will work for you depends on how noisy your environment is. You'd have to do your own tests.