PCB LAYOUT CONSIDERATIONS

In order to meet the USB requirements for voltage drop,

droop and EMI, each component used in this circuit must be

evaluated for its contribution to the circuit performance. The

PCB layout rules and guidelines must be followed.

•

Place the switch as close to the USB connector as pos-

sible. Keep all V

least 50-mil, 1 ounce copper for all V

plating the traces will reduce the trace resistance.

•

Avoid vias as much as possible. If vias are used, use mul-

tiple vias in parallel and/or make them as large as pos-

sible.

•

Place the output capacitor and ferrite beads as close to

the USB connector as possible.

•

If ferrite beads are used, use wires with minimum resis-

tance and large solder pads to minimize connection re-

sistance.

DS101097-23

FIGURE 2. Self-Powered Hub Per-Port Voltage Drop

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