sc1470 Semtech Corporation, sc1470 Datasheet - Page 17

• Manufacturer Part Number: sc1470
• Description: Synchronous Buck Pseudo Fixed Frequency Power Supply Controller
• Manufacturer: Semtech Corporation

As shown below, VOUT and VSSA should be routed as a differential pair to the output capacitor(s).
Next, the schematic in Figure 8 below shows the power section. The highest di/dts occur in the input loop (highlighted
in red) and thus this loop should be kept as small as possible.
The input capacitors should be placed with the highest frequency capacitors closest to the loop to reduce EMI. Use
large copper pours to minimize losses and parasitics. See Figure 9 for an example.
POWER MANAGEMENT
2005 Semtech Corp.
VOUT
C6
56p
0402
Figure 7: Differential Routing of Feedback and Ground Reference Traces
VOUT
VOUT
R4
20k0
0402
R8
14k3
0402
IRF7811AV
FDS6676S
C11
1uF
0603
Q1
Q2
Figure 8: Power Section and Input Loop
1
2
3
4
5
6
7
U2
VBAT
EN/PSV
TON
VOUT
VCCA
FB
PGD
VSSA
C2
2n2/50V
0402
L1
SC470
VSSA
PGND
VDDP
2u2
ILIM
BST
DH
DL
R6 0R (2)
LX
C3
0u1/25V
0603
0402
17
14
13
12
11
10
9
8
C4
10u/25V
1210
+
C6
220u/25m
7343
+
C7
220u/25m
7343
R12 0R (2)
0402
VOUT
+
C14
220u/25m
7343
+
C7
220u/25m
7343
VOUT
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SC1470