Place the protection and filtering circuitry close to the bus connector, J1, to prevent transients, ESD, and noise from propagating onto the board. This layout example shows optional transient voltage suppression (TVS) diodes, D1 and D2, which may be implemented if the system-level requirements exceed the specified rating of the transceiver. This example also shows optional bus filter capacitors C4, C5, C6, and C8.
Design the bus protection components in the direction of the signal path. Do not force the transient current to divert from the signal path to reach the protection device.
Decoupling capacitors should be placed as close as possible to the supply pins VCC1 and VCC2 of the transceiver.
Use at least two vias for supply and ground connections of bypass capacitors and protection devices to minimize trace and via inductance.
Note:
High frequency current follows the path of least impedance and not the path of least resistance.
This layout example shows how split termination could be implemented on the CAN node. The termination is split into two pairs of resistors, R7, R8, R9, and R10, with the center or split tap of the termination connected to ground via capacitors C3 and C7. Split termination provides common mode filtering for the bus. See Section 9.2.1.1, Section 8.3.4, and Equation 2 for information on termination concepts and power ratings needed for the termination resistor(s).