SC411 Semtech Corporation, SC411 Datasheet - Page 18

• Manufacturer Part Number: SC411
• Description: Synchronous Buck Pseudo-Fixed Frequency Power Supply Controller
• Manufacturer: Semtech Corporation

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The layout can be considered in two parts, the control section referenced to VSSA and the power section. Looking at
the control section fi rst, locate all components referenced to VSSA on the schematic and place these components at
the chip. Drop vias to the ground plane as needed.
In Figure 6 above, all components referenced to VSSA have been placed and connected to the ground plane with
vias.
with vias. Note how the VSSA and PGND pins are connected directly to the thermal pad, which has 4 vias to the
ground plane (not shown).
© 2007 Semtech Corp.
POWER MANAGEMENT
Decoupling
capacitors C9 and C10 are as close as possible to their pins and connected to the ground plane
VBAT
R1
1M
0402
C8
1nF
0402
Figure 5: Components Connected to VSSA
C5
56p
0402
VOUT
Figure 6: Control Section Example
R3
20k0
0402
R5
14k3
0402
R2
10R
0402
5VSUS
C9
1uF
0603
1
2
3
4
VOUT
VCCA
FB
PGD
U1
18
SC411
VDDP
ILIM
DH
LX
12
11
10
9
5VSUS
C10
1uF
0603
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SC411