11.1 Layout Guidelines

For printed circuit board (PCB) layout of the TCA8418, common PCB layout practices should be followed, but additional concerns related to high-speed data transfer, such as matched impedances and differential pairs are not a concern for I²C signal speeds.

In all PCB layouts, it is best practice to avoid right angles in signal traces, to fan out signal traces away from each other upon leaving the vicinity of an integrated circuit (IC), and to use thicker trace widths to carry higher amounts of current that commonly pass through power and ground traces. Bypass and de-coupling capacitors are commonly used to control the voltage on the VCC pin, using a larger capacitor to provide additional power in the event of a short power supply glitch and a smaller capacitor to filter out high-frequency ripple. These capacitors should be placed as close to the TCA8418 as possible.

For the layout example provided in Layout Example, a 4 layer board is required to route all of the signals. The layout example shows a way to route the signals out from the device, which can eventually be brought up to the top layer (or any required layer) with the use of a via. This technique is not demonstrated in this example due to the complexity of the layout.