Datasheet

PCB Layout Guidelines

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9 PCB Layout Guidelines

This section provides general practical guidelines for PCB layouts that use various power and ground

traces. Designers should note that these are only “rule-of-thumb” recommendations and the actual results

are predicated on the final layout.

9.1 Power and Ground Circuits

Star trace routing techniques can have a major positive impact on low-level signal performance. Star trace

routing refers to using individual traces that radiate from a signal point to feed power and ground to each

circuit or even device.

9.2 Layout Helpful Hints:

1. Avoid routing traces under the inductor.

2. Use three separate grounds that eventually connect to one point:

(a) Signal or quiet ground (GND2)

(b) Ground for the LM48511 device (GND1)

therefore is the nosiest. Make this trace as wide and short as possible and keep at a distance from

the quiet ground and device ground. Give distance priority to the quiet ground.

10 Bill Of Materials

Designator Description Footprint Qty Value

Cf1 CHIP CAPACITOR GENERIC CAP 0805 1 470pF

CINA CHIP CAPACITOR GENERIC CAP 1210 1 1μF

CINB CHIP CAPACITOR GENERIC CAP 1210 1 1μF

Co CHIP CAPACITOR GENERIC CAP 1210 1 10μF

Cs1 CHIP CAPACITOR GENERIC CAP 1210 1 2.2μF

Cs2 CHIP CAPACITOR GENERIC CAP 1210 1 4.7μF

D1 SCHOTTKY DIODE DIODE MBR0520 IR 1

L1 IND_COILCRAFT-DO1813P 1 4.7μH

R1 CHIP RESISTOR GENERIC RES 0805 1 41.2K

R2 CHIP RESISTOR GENERIC RES 0805 1 13.3K

RINA CHIP RESISTOR GENERIC RES 0805 1 150K

RINB CHIP RESISTOR GENERIC RES 0805 1 150K

11 Demonstration Board PCB Layout

Figure 3 through Figure 8 shows the different layers used to create the LM48511SQ demonstration board.

Figure 3 is the silkscreen that shows component locations on the board’s top surface. Figure 4 is the

metal Top Layer. Figure 5 is the metal Midlayer 1. Figure 6 is the metal Midlayer 2. Figure 7 is the metal

Bottom Layer. Figure 8 is the silkscreen that shows component locations on the board bottom.

AN-1922 LM48511 Evaluation Board SNAA064C–November 2008–Revised May 2013

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