CAN Bus PCB Routing – Two Nodes with Unequal Distance to Single Connector

Design and Layout
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1

Hi Friends,

I am working on a PCB design with the following CAN architecture:

  • Two MCUs on the same board

  • Each MCU has its own CAN transceiver

  • Both transceivers are connected to a common CANH and CANL connector (single CAN bus)

The challenge I am facing is related to routing:

  • One transceiver is placed very close to the connector

  • The other transceiver is approximately 30 cm away from the connector

My understanding from CAN layout guidelines is:

  • CAN should follow a linear bus topology

  • Nodes should be connected using short stubs

  • Long stubs can cause signal reflections and integrity issues, especially at higher bit rates

In this scenario, what is the recommended routing approach?

  1. Should I treat the 25 cm trace as a stub (which seems too long )?

  2. Or should I route a main CAN bus line across the PCB (from the far transceiver → near transceiver → connector), and connect both transceivers inline to this bus?

    Regarding termination:

    • Should I place a single 120Ω termination resistor for the entire bus (only if the board is at the end)?

    • Or should each transceiver have its own termination resistor?

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2

For routing CAN bus use the second option. Route it in a daisy chain fashion, from connector to near end transceiver then from near end transceiver to the far end transceiver, this way you will avoid stubs. Regarding the termination resistor use only one 120 ohms termination resistor at the far end of the CAN bus that is near the far end transceiver.

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3

Is a single termination sufficient for this setup?

4

I assume one termination on this board and one termination on whatever board exists on the far end of the CAN bus.

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5

I have doubt regarding the Placement 120 ohm termination resistor for differential line routing,

  1. first transceiver at far end distance on same board - termination resistor - second transceiver near connector on same board - connector

  2. first transceiver at far end distance - second transceiver near connector - termination resistor - connector

    which one should i follow ?

6

Keep CAN wiring as one straight line with very short connections to each node :+1:

7

Single termination on the board that you were talking about with connector and two transceivers.

8

Yes correct

9

Termination resistor → Far end CAN Bus transceiver → Near end CAN bus transceiver → connector. Basically the shunt termination should be at the far end of the CAN bus. If the CAN bus is directly ending at the pins of far end CAN bus transceiver then the termination would be close to the pins of Far end CAN bus transceiver.

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10

Thank You for your support

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