Place the protection and filtering circuitry as close to the bus connector, J1, to prevent transients, ESD and noise from propagating onto the board. The layout example provides information on components around the device itself. Transient voltage suppression (TVS) device can be added for extra protection, shown as D1. The production solution can be either bi-directional TVS diode or varistor with ratings matching the application requirements. This example also shows optional bus filter capacitors C10 and C11. A series common mode choke (CMC) is placed on the CANH and CANL lines between TCAN114x-Q1 and connector J1.
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. Use supply and ground planes to provide low inductance.
A high-frequency current follows the path of least impedance and not the path of least resistance.
Use at least two vias for supply and ground connections of bypass capacitors and protection devices to minimize trace and via inductance.