3. TECHNICAL BRIEF
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Only for training and service purposes
LGE Internal Use Only
3. TECHNICAL BRIEF
3.1.7 Buck Convertor (SC424, U1&2)
We use two SC424 U2 is for BCM5358U and U1 is for LTE Module U2 output voltage is set to 3 3V and U1 output
We use two SC424. U2 is for BCM5358U and U1 is for LTE Module. U2 output voltage is set to 3.3V and U1 output
voltage is set to 3.75V. The current limit setting is 2.16A same. We use 12V main power source from Adaptor.
The SC424 convert down from 12V to 3.3V and 3.75V for all circuit applications.
Figure 3.7 SC424 Circuit Diagram
C3
1u
C8
2.2u
C9
10n
2
R
K1.
91
C12
47p
C1
DNI
SPPH410100
4
3
5
2
6
1
20
1
N
C
ESPY0001701
C4
1u
R7
2.7K
01
R
K7
4
U2
EUSY0369702
SC424
3
31
6
1
30
32
72
92
62
22
01
52
15
31
16
20
19
82
41
21
8
9
7
2
42
21
5
18
11
17
4 VOUT
PGND4
4
NI
V
PGND5
VIN
T
S
B
XL
S
XL
V5V
BST
2
NI
V
1
NI
V
LX3
2
D
N
G
P
L
N
E
PGND6
LX2
PGND3
1
D
N
G
P
LX1
V
S
P/
N
E
3
NI
V
D
O
O
G
P
2
D
N
G
A
3
D
N
G
A
N
OT
MI
LI
VIN5
FB
VLDO
LX4
AGND1
R11
100K
C18
100n
100n
C19
SC424
EUSY0369702
U1
3
31
6
1
30
32
72
92
62
22
01
52
15
31
16
20
19
82
41
21
8
9
7
2
42
21
5
18
11
17
4 VOUT
PGND4
4
NI
V
PGND5
VIN
T
S
B
XL
S
XL
V5V
BST
2
NI
V
1
NI
V
LX3
2
D
N
G
P
L
N
E
PGND6
LX2
PGND3
1
D
N
G
P
LX1
V
S
P/
N
E
3
NI
V
D
O
O
G
P
2
D
N
G
A
3
D
N
G
A
N
OT
MI
LI
VIN5
FB
VLDO
LX4
AGND1
K7
4
9
R
1u
C5
DNI
C2
47p
C11
K1.
91
1
R
10n
C10
2.2u
C7
1u
C6
C115
DNI
KRX102U
EQBA0000601
10
1
Q
5
4
1
2
3
0
42
1
R
32
1
R
K0
1
C126
DNI
L100
2.2u
2.2u
L101
100K
R12
DNI
R13
R14
100K
VA100
51
R
K0
21
LD100
EDLM0009901
67-21-L9C-W4556W1X1B2-2T
C15
10u
VDD_3.75
0.1u
C103
VDD_3.3
R8
2.7K
0.1u
C121
C104
22u
I
N
D
01
1
R
DNI
C110
C119
22u
5
R
K0
3
DNI
C116
C14
10u
55
1
R
I
N
D
6
R
K6
1
3
R
K6
5
R102
100K
R104
10
100K
R103
1K
R114
Q100
EQBN0005301
UMT2222A
1
2
3
C120
22u
C101
22u
C105
22u
10u
C13
C102
22u
PWR_LED
LTE_PWR_EN
NP_EN
LTE_EN
Power LED(White)
FOR N.P POWER [3.3V/2.16A]
FOR LTE MODULE POWER [3.75V/2.16A]