SOLDER MASK

OPENING, TYP

METAL UNDER

SOLDER MASK,

TYP

8 mil

8 mil

0402

0.1 …F

Bypass

Capacitor

8 mil

WORST

BETTER

BEST

13

SN74LVC1GU04

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SCES215Y – APRIL 1999 – REVISED DECEMBER 2017

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Copyright © 1999–2017, Texas Instruments Incorporated

11 Layout

11.1 Layout Guidelines

Even low data rate digital signals can contain high-frequency signal components due to fast edge rates. When a

printed-circuit board (PCB) trace turns a corner at a 90° angle, a reflection can occur. A reflection occurs

primarily because of the change of width of the trace. At the apex of the turn, the trace width increases to 1.414

times the width. This increase upsets the transmission-line characteristics, especially the distributed capacitance

and self–inductance of the trace which results in the reflection. Not all PCB traces can be straight and therefore

some traces must turn corners. Figure 7 shows progressively better techniques of rounding corners. Only the last

example (BEST) maintains constant trace width and minimizes reflections.

An example layout is given in Figure 8 for the DPW (X2SON-5) package. This example layout includes a 0402

(metric) capacitor and uses the measurements found in the example board layout appended to this end of this

datasheet. A via of diameter 0.1 mm (3.973 mil) is placed directly in the center of the device. This via can be

used to trace out the center pin connection through another board layer, or it can be left out of the layout

11.2 Layout Example

Figure 7. Trace Example

Figure 8. Example Layout With DPW (X2SON-5) Package