SC486 Semtech Corporation, SC486 Datasheet - Page 20

• Manufacturer Part Number: SC486
• Description: Complete DDR1/2/3 Memory Power Supply
• Manufacturer: Semtech Corporation

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Layout Guidelines (Cont.)
The layout can be considered in three parts, the control section referenced to VSSA, the VTT output, and the
switcher power section. Looking at the control section first, locate all components referenced to VSSA1 on the
schematic and place these components at the chip. Connect VSSA using a wide (>0.020”) trace. Very little current
flows in the chip ground therefore large areas of copper are not needed. Connect the VSSA pin directly to the
thermal pad under the device as the only connection to PGND from VSSA.
POWER MANAGEMENT
2006 Semtech Corp.
VDDQ
REF
C1
no-pop
R5
23k2
R4
4k64
R8
10R
Figure 7: Components Connected to VSSA
C2
1u
Figure 8: Example VSSA 0.020” Trace
R6
10R
C9
1u
R7
C10
no-pop
10R
C3
no-pop
20
C11
1n
C12
1u
5VRUN
11
10
14
15
12
13
16
17
3
2
6
8
9
5
4
U1
VTTEN
VDDQS
TON
FB
REF
COMP
VTTS
VCCA
VSSA
VTT
VTT
VTTIN
VTTIN
PGND2
PGND2
PAD
EN/PSV
PGND1
VDDP
SC486
PGD
ILIM
BST
DH
DL
LX
7
1
24
23
21
22
19
20
18
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SC486
C18
1u