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