CD74HC4052PWR datasheet(25/45 Pages) TI1

25 / 45 page

WORST

BETTER

BEST

1W min.

CD54HC4051, CD74HC4051

CD54HCT4051, CD74HCT4051, CD54HC4052, CD74HC4052, CD54HCT4052

CD74HCT4052, CD54HC4053, CD74HC4053, CD54HCT4053, CD74HCT4053

www.ti.com

SCHS122K – NOVEMBER 1997 – REVISED SEPTEMBER 2015

11 Layout

11.1 Layout Guidelines

Reflections and matching are closely related to loop antenna theory, but different enough to warrant their own

discussion. When a PCB trace turns a corner at a 90° angle, a reflection can occur. This is primarily due to the

change in width of the trace. At the apex of the turn, the trace width is increased to 1.414 times its width. This

change in width upsets the transmission line characteristics, especially the distributed capacitance and self-

inductance of the trace, thus resulting in the reflection. Not all PCB traces can be straight, so they will have to

turn corners. Figure 22 shows progressively better techniques of rounding corners. Only the last example (BEST)

maintains constant trace width and minimizes reflections.

11.2 Layout Example

Figure 22. Trace Example

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CD74HC4052PWR Datasheet(PDF) 25 Page - Texas Instruments