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LTC3545/LTC3545-1

35451fb

PC Board Layout Checklist

When laying out the printed circuit board, the following

checklist should be used to ensure proper operation of

the LTC3545/LTC3545-1. These items are also illustrated

graphically in Figures 3 and 4. Figure 3 shows the power

path components and traces. In this ﬁgure the feedback

networks are not shown since they reside on the bottom

side of the board. Check the following in your layout:

1. The power traces consisting of the PGND trace, the SW

trace, the PVIN trace, the VIN and GNDA traces, should

be kept short direct and wide.

2. Does each of the VFBx pins connect directly to the

respective feedback resistors? The resistive dividers

must be connected between the (+) plate of the cor-

responding output ﬁlter capacitor (e.g. C2) and GNDA.

If the circuit being powered is at such a distance from

the part where voltage drops along circuit traces are

large, consider a Kelvin connection from the powered

circuit back to the resistive dividers.

3. Keep C1 and C5 as close to the part as possible.

4. Keep the switching nodes (SWx) away from the sensi-

tive VFBx nodes.

5. Keep the ground connected plates of the input and

output capacitors as close as possible.

6. Care should be taken to provide enough space between

unshielded inductors in order to minimize any trans-

former coupling.

APPLICATIONS INFORMATION

Figure 3. Layout Diagram

VOUT3

(VIA TO FEEDBACK

NETWORK)

(VIA TO FEEDBACK

NETWORK)

(VIA TO FEEDBACK

NETWORK)

VOUT2

PGND

PVIN

SW3

SW2

SW1

VOUT1

VIN

GNDA

3545 F03

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