PROGRAMMABLE SYNCHRONOUS DC/DC
CONVERTER, DUAL LOW DROPOUT
REGULATOR CONTROLLER
SC1182/3
August 25, 1998
MATERIALS LIST
Qty. Reference
Part/Description
Vendor
Notes
4
6
6
C1,C5,C13, 0.1µF Ceramic
C18
Various
C2,C3,C14- 1500µF/6.3V
C17
SANYO
Various
MV-GX or equiv. Low ESR
C9-C12,
330µF/6.3V
C21, C22
1
4
L1
4µH
8 Turns 16AWG on MICROMETALS T50-52D core
FET selection requires trade-off between efficiency and
Q1,Q2,Q3,
Q4
See notes
See notes
cost. Absolute maximum RDS(ON) = 22 m for Q1,Q2
Ω
1
1
1
1
1
1
1
1
2
1
R4
IRC
OAR-1 Series
5m
Ω
R5
Various
Various
Various
Various
Various
Various
Various
Various
SEMTECH
2.32k , 1%, 1/8W
Ω
R6
1k , 1%, 1/8W
Ω
R1
10 , 5%, 1/8W
Ω
R12
R13
R14
R15
R17, R18
U1
1%, 1/8W
See Table Below (Not required for SC1182)
See Table Below (Not required for SC1182)
See Table Below (Not required for SC1182)
See Table Below (Not required for SC1182)
1%, 1/8W
1%, 1/8W
1%, 1/8W
100K, 5%, 1/8W
SC1182/3CSW
SETTING LDO OUTPUT VOLTAGE
1.265 (RA R )
+
B
RB
RA
VOUT
(I RA )
FB
=
+
RB
VOUT LDO1 (LDO2)
3.45V
R12 (R14)
R13 (R15)
Where :
IFB Feedback pin bias current
105
105
102
100
100
100
100
182
169
147
130
121
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Ω
=
3.30V
RA Top feedback resistor
=
3.10V
RB Bottom feedback resistor
=
2.90V
See layout diagram for clarification
RA andRB must be low enough so
that the (IFB RA ) term does not cause
significant error
2.80V
2.50V
97.6
Ω
Ω
1.50V
18.7
6
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652 MITCHELL ROAD NEWBURY PARK CA 91320
SEMTECH [ SEMTECH CORPORATION ]
