SC486 Semtech Corporation, SC486 Datasheet - Page 21

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

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Layout Guidelines (Cont.)
In Figure 8, all components referenced to VSSA have been placed and have been connected using a 0.020” trace.
Decoupling capacitor C12 is as close as possible to VCCA and VSSA and the VDDP decoupling capacitor C18 is as
close as possible to VDDP and PGND1. The feedback components R5, R8 and C1 along with the VDDQ sense
components, R4 and C2 are also located at the chip and the feedback trace from the VDDQ output should route
from the top of the output capacitors (C13 and C14) in a quiet layer back to these components. In Figure 8, the
VDDQ feedback trace would connect to the red trace.
POWER MANAGEMENT
2006 Semtech Corp.
C1
no-pop
Figure 9: VDDQ Feedback and Sense Components and Feedback Trace
R5
23k2
VDDQ FEEDBACK
R4
4k64
R8
10R
C2
1u
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
21
ILIM
BST
DH
DL
LX
7
1
24
23
21
22
19
20
18
+
C13
220u/15m
+
C14
220u/15m
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VDDQ
SC486