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SN65LBC031: Signaling rate and ASC pin setting

Shotaro Sakai
Intellectual 2890 points
Part Number: SN65LBC031
Other Parts Discussed in Thread: SN75LBC031, SN65HVD251

Hello team,

I have three questions for SN65LBC031.

1. The datasheet describes that "The SN75LBC031 is a CAN transceiver used as an interface between a CAN controller and the physical bus for high speed applications of up to 500 kBaud".

But on the TI.com page, SN65LBC031 supports up to 1MHz. Which is correct value?

2. My customer is considering to use SN65LBC031QDR instead of SN65HVD251DR.

Rs pin (Mode select) of SN65HVD251DR is set by 1kΩ pulldown. To achieve similar spec with SN65LBC031QDR, how to set ASC pin?

3. Do you think this replace is no problem? P2P device is must be needed so I proposed The SN75LBC031.

Best regards,

Shotaro

  • 0
    TI__Guru 50795 points

    Hi Sakai-san,

    1. The datasheet is correct. This device only supports up to 500kbps data rates. I believe the display on ti.com rounded this to 1Mbps as most modern transceivers specify rates of this order of magnitude. 

    2. The older SN65LBC031 drives a slew rate between 10-35V/µs. A similar configuration for SN65HVD251 would have a pull-down of 10kΩ to achieve a target slew rate of 15V/µs. See datasheet section 8.3.3. 

    3. While this replacement may look fine on paper, replacing SN65HVD251 with a much older transceiver may not be the best solution if this is a supply concern. There is little existing stock for SN65LBC031 and we mostly prioritize production of newer devices because of the more modern production processes. From a technical viewpoint, it's likely that this replacement could work in place of the newer device, but compromises may need to be made for the lower data rate support, bus fault tolerance, and ESD capabilities. 

    Regards,
    Eric Schott