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SN65HVD1040: schematic review

Fred Cheng
Expert 5970 points

Part Number: SN65HVD1040

Hi 

Is there any recommendation on this schematic?

especially at CANL and CANH

  • 0
    TI__Guru 53535 points

    Hi Fred,

    Overall the schematic looks pretty good. I have a few comments to optimize things a bit and correct what may be a misunderstanding on the use of Split Termination. Let me know if there are any questions or concerns regarding this feedback. 

    • Single termination used on CAN bus (R323), but partial Split termination used as well (R321, R322). 
      • Recommend using Split termination only. Two 60-ohm resistors in series between CANH and CANL with Split capacitor and SPLIT pin connected in between. Place termination on bus-side of CMC (current location of R323).
      • See DS figure 29 for schematic example. See Figure 34 for layout example. 
        • CMC not shown in example, but should be placed between transceiver and termination. 
    • Recommend adding 100nF capacitor near Vcc pin for power decoupling. 
    • Ensure capacitance of CAN_RX_ISO line has low enough capacitance for open-drain drive with 1k-ohm pull-up. 
    • STB tied to GND, low power mode not available - no issue. 
    • Bus capacitors included and valued appropriately - ensure placement close to board connectors.
    • TVS diodes included - ensure placement close to board connectors. 

    Regards,
    Eric Schott