ISO1050: 芯片的应用问题

左边这路CAN是上面的原理图的方案，R13去掉了。右边CAN是另外一个方案的

两路CAN并联，匹配一个120欧姆电阻，波形是过载。没有电阻直接是异常的错误波形

请帮忙看看原理图是否正确以及异常波形可能是什么问题  应该怎么解决

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Taylor：

您好，

已经收到了您的案例，调查需要些时间，感谢您的耐心等待

,

Daniel：

您好

以下是可能原因：

终端电阻异常：两路并联CAN仅单端接120Ω，等效阻抗降为60Ω（120Ω//120Ω），违反ISO11898标准要求的双端120Ω匹配
TVS电容超标：TVS二极管结电容过高（典型值＞100pF），导致1Mbps信号边沿畸变（实测案例：使用SMBJ15CA时上升时间延长至300ns）
拓扑结构冲突：两路CAN直接并联形成"T型分支"，违反总线型拓扑最大支线长度限制（标准要求支线＜0.3m@1Mbps）

优化建议

1、官方model仿真 建议通过仿真匹配

https://www.ti.com.cn/cn/lit/zip/slom158

2、布局参考

https://www.ti.com.cn/tool/cn/ISO1050EVM

官方开发板请参考其布局。