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 TCAN146x-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.

Use at least two vias for supply and ground connections of bypass capacitors and protection devices to minimize trace and via inductance.

• Bypass and bulk capacitors should be placed as close as possible to the supply terminals of transceiver, examples are C1 V_CC and C2 on V_IO, pins and C4 and C5 on the V_SUP supply.
• Bus termination: this layout example shows split termination. This is where the termination is split into two resistors, R4 and R5, with the center or split tap of the termination connected to ground via capacitor C6. Split termination provides common mode filtering for the bus. When bus termination is placed on the board instead of directly on the bus, additional care must be taken to be sure the terminating node is not removed from the bus; thus, removing the termination.
• As terminal 6 (SDO/nINT) is an open drain, when working as nINT, an external resistor to V_IO is required. These can have a value between 2kΩ and 10kΩ.
• Terminal 7(INH) can have a 100kΩ resistor to ground if not used.
• Terminal 9 (WAKE) is a bi-directional wake up that is usually connected to an external switch. It should be configured as shown with C3 which is a 22nF capacitor to GND where R2 is 33kΩ and R3 is 3kΩ.
• Terminal 14 is the nCS pin.