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 a optional transient voltage suppression (TVS) diode, D1, 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 and C5.
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 VCC and VIO of 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 resistors, R2 and R3, with the center or split tap of the termination connected to ground via capacitor C3. Split termination provides common mode filtering for the bus. See Section 10.2.1.1, Section 9.3.4, and Equation 2 for information on termination concepts and power ratings needed for the termination resistor(s).