05721

September 12, 2012

Rev: C

EP5348UI

©Enpirion 2012 all rights reserved, E&OE

10

www.enpirion.com

Figures 4 and 5 show critical PCB top and

bottom layer components and traces for a

minimum-footpint

recommended

EP5348

ENABLE configurations need to be connected

and routed according to specific customer

application. This layout consists of four layers.

For

the

other

2

layers

and

the

exact

dimensions, please see the Gerber files at

The

recommendations

given below are general guidelines. Customers

may need to adjust these according to their

own layout and manufacturing rules.

Recommendation 1: Input and output filter

capacitors should be placed on the same side

of the PCB, and as close to the EP5348UI

package

as

possible.

They

should

be

connected to the device with very short and

wide traces. Do not use thermal reliefs or

spokes when connecting the capacitor pads to

the respective nodes. The +V and GND traces

between the capacitors and the EP5348UI

should be as close to each other as possible

so that the gap between the two nodes is

minimized, even under the capacitors.

Recommendation 2: The system ground

plane should be the first layer immediately

below the surface layer. This ground plane

should be continuous and un-interrupted below

the converter and the input/output capacitors.

Recommendation 3: Multiple small vias

should be used to connect ground terminal of

the input capacitor and output capacitors to the

system ground plane. It is preferred to put

these vias along the edge of the GND copper

closest to the +V copper. These vias connect

the input/output filter capacitors to the GND

plane, and help reduce parasitic inductances in

the input and output current loops. See Figure

to minimize the footprint. These components

also need to be close to the VFB pin (see

Figures 3, 4 and 5). The VFB pin is a high-

impedance, sensitive node. Keep any trace

connected to this node as short and thin as

directly to the AGND pin instead of going

through the GND plane. In the layout shown

using a dedicated trace on layer 3 not shown

Recommendation 5: AVIN is the power supply

for the small-signal control circuits. It should be

connected to the input voltage at a quiet point.

In Figure 4 this connection is made at the vias

connected between the device pin and the

GND plane.

Recommendation 6: The via to the right of pin

2 underneath the device helps to minimize the

parasitic inductances in the input and output

loop ground connections.

Recommendation 7: The top layer 1 metal

under the device must not be more than shown

in Figure 4. As with any switch-mode DC/DC

converter, try not to run sensitive signal or

control lines underneath the converter package

on other layers.

should be just after the last output filter

capacitor. Keep the sense trace short in order

to avoid noise coupling into the node.