POWER MANAGEMENT
1
www.semtech.com
SC104
Micro Power Constant-Current
DC-DC Converter
Revision: September 19, 2003
The SC104 is a micro power dc-dc step-up converter
which converts an input voltage, in the range of 1.55V to
10V, to a constant current. The part features a range of
user programmable voltages and currents including
dynamic adjustment of the "constant" current. The
converter is capable of generating output voltages as
low as the input supply voltage and up to 38V. During
shutdown, the part draws a typical 500nA standby
current.
The output current is set by the external resistor R1.
Dynamic adjustment of the output current can be made
by the application of an analog voltage to the ADJ
input, or by PWMing this pin.
The peak switch current is programmable through the
external resistor R
LIM
enabling the use of a wide range of
inductors and battery technologies.
White LED supplies
Color LED supplies
Cellular phones
PDAs
Electronic books
Handheld computers
Wireless web appliances
Adjustable output current using pulse width
modulation or analog voltage input
38V output capability supports up to 10 white LEDs
Wide range of input voltages 1.55V to 10V
Low quiescent current
0.5A standby current in shutdown
Programmable cycle by cycle current limit
Surface mount packaging (3x3mm 8pin MLP)
Output voltage and over-temperature protection
Description
Features
Applications
Typical Application Circuit - 6 LEDs
ENABLE
RSET
23.2R
LED2
D1
IOUT = 15mA
U1
SC104
1
2
3
4
5
6
7
8
ADJ
FB
GND
OUT
LX
IN
LIM
EN
LED1
LED3
VIN = 3V to 5V
LED5
RLIM
7.50k
LED4
CIN
4.7uF
IOUT ADJUST
L1
12uH
LED6
COUT
0.47uF
2
2003 Semtech Corp.
www.semtech.com
SC104
POWER MANAGEMENT
r
e
t
e
m
a
r
a
P
l
o
b
m
y
S
m
u
m
i
x
a
M
s
t
i
n
U
e
g
a
tl
o
V
y
l
p
p
u
S
t
u
p
n
I
V
N
I
2
1
o
t
3
.
0
-
V
e
g
a
tl
o
V
n
i
P
X
L
)
F
F
O
h
c
ti
w
s
r
e
w
o
P
(
V
X
L
5
5
o
t
3
.
0
-
V
e
g
a
tl
o
V
n
i
P
B
F
V
B
F
6
o
t
3
.
0
-
V
e
g
a
tl
o
V
n
i
P
N
E
V
N
E
6
o
t
3
.
0
-
V
e
g
a
tl
o
V
n
i
P
M
I
L
V
M
I
L
6
o
t
3
.
0
-
V
e
g
a
tl
o
V
n
i
P
J
D
A
V
J
D
A
2
o
t
3
.
0
-
V
e
g
a
tl
o
V
n
i
P
T
U
O
V
T
U
O
5
5
o
t
3
.
0
-
V
t
n
e
i
b
m
A
o
t
n
o
it
c
n
u
J
e
c
n
a
d
e
p
m
I
l
a
m
r
e
h
T
A
J
4
8
W
/
C
e
g
n
a
R
e
r
u
t
a
r
e
p
m
e
T
t
n
e
i
b
m
A
g
n
it
a
r
e
p
O
T
A
5
8
+
o
t
0
4
-
C
e
g
n
a
R
e
r
u
t
a
r
e
p
m
e
T
n
o
it
c
n
u
J
g
n
it
a
r
e
p
O
T
J
4
-
5
2
1
+
o
t
0
C
e
g
n
a
R
e
r
u
t
a
r
e
p
m
e
T
e
g
a
r
o
t
S
T
G
T
S
0
5
1
+
o
t
5
6
-
C
s
0
3
-
s
0
1
)
g
n
ir
e
d
l
o
S
(
e
r
u
t
a
r
e
p
m
e
T
d
a
e
L
T
D
A
E
L
0
4
2
C
)l
e
d
o
M
y
d
o
B
n
a
m
u
H
(
g
n
it
a
R
D
S
E
V
D
S
E
2
V
k
Absolute Maximum Ratings
Unless specified: V
IN
= V
EN
= 2V, -40
T
A
85C, typical values are at room temperature.
r
e
t
e
m
a
r
a
P
l
o
b
m
y
S
s
n
o
i
t
i
d
n
o
C
t
s
e
T
n
i
M
p
y
T
x
a
M
s
t
i
n
U
e
g
a
tl
o
V
y
l
p
p
u
S
t
u
p
n
I
V
N
I
T
A
5
2
=
o
C
5
5
.
1
0
1
V
5
7
.
1
0
1
t
n
e
r
r
u
C
n
w
o
d
t
u
h
S
I
)
F
F
O
(
Q
V
N
E
V
0
=
5
.
0
3
A
e
g
a
tl
o
V
k
c
a
b
d
e
e
F
V
B
F
0
4
3
0
5
3
0
6
3
V
m
t
n
e
r
r
u
C
t
u
p
n
I
k
c
a
b
d
e
e
F
I
B
F
V
B
F
V
m
0
5
3
<
0
0
2
0
0
7
5
1
1
1
A
n
h
c
ti
w
S
r
e
w
o
P
e
g
a
tl
o
V
n
o
it
a
r
u
t
a
S
V
)
T
A
S
(
E
C
I
X
L
A
m
0
0
3
=
0
5
1
0
5
2
V
m
l
a
m
r
e
h
T
t
a
e
r
u
t
a
r
e
p
m
e
T
n
o
it
c
n
u
J
n
w
o
d
t
u
h
S
)
1
(
T
D
S
T
0
4
1
0
5
1
0
6
1
o
C
n
o
it
c
e
t
o
r
P
e
g
a
tl
o
V
-
r
e
v
O
V
P
V
O
A
0
1
=
t
n
e
r
r
u
c
t
s
e
T
6
3
8
3
4
4
V
e
g
a
tl
o
V
t
s
u
j
d
A
V
J
D
A
I
J
D
A
A
0
=
7
9
.
0
0
0
.
1
3
0
.
1
V
ti
b
i
h
n
I
g
n
i
h
c
ti
w
S
e
g
a
tl
o
V
t
s
u
j
d
A
d
l
o
h
s
e
r
h
T
V
)
J
D
A
(
H
T
0
0
1
V
m
t
n
e
r
r
u
C
t
u
p
n
I
t
s
u
j
d
A
I
J
D
A
V
J
D
A
V
0
=
6
0
1
0
2
A
V
J
D
A
V
1
=
0
0
5
-
0
0
0
5
A
n
V
J
D
A
V
5
2
.
1
=
3
.
1
-
3
.
2
-
8
.
3
-
A
Electrical Characteristics
Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified
in the Electrical Characteristics section is not implied.
3
2003 Semtech Corp.
www.semtech.com
SC104
POWER MANAGEMENT
r
e
t
e
m
a
r
a
P
l
o
b
m
y
S
s
n
o
i
t
i
d
n
o
C
t
s
e
T
n
i
M
p
y
T
x
a
M
s
t
i
n
U
t
n
e
r
r
u
C
h
c
ti
w
S
m
u
m
i
x
a
M
I
X
L
I
M
I
L
A
0
5
1
=
0
2
9
-
mA
e
m
i
T
ff
O
h
c
ti
w
S
t
F
F
O
V
B
F
V
m
0
0
3
=
0
6
.
0
6
7
.
0
0
0
.
1
s
V
B
F
V
0
=
0
0
.
1
5
2
.
1
0
6
.
1
e
m
i
T
n
O
h
c
ti
w
S
t
N
O
s
n
o
it
i
d
n
o
c
d
e
ti
m
il
t
n
e
r
r
u
c
s
e
d
u
l
c
x
e
8
.
1
5
2
.
2
7
.
2
s
e
l
c
y
C
y
t
u
D
m
u
m
i
x
a
M
%
C
D
0
7
%
e
g
a
k
a
e
L
h
c
ti
w
S
I
X
L
V
,f
f
o
h
c
ti
w
s
X
L
V
5
=
1
0
.
0
-
0
.
1
-
A
ti
m
i
L
t
n
e
r
r
u
C
r
o
f
e
c
n
e
r
e
f
e
R
e
g
a
tl
o
V
r
o
t
s
i
s
e
R
g
n
it
t
e
S
V
M
I
L
I
M
I
L
A
0
5
=
5
8
3
0
0
4
0
1
4
V
m
I
X
L
I
o
t
M
I
L
o
it
a
R
I
X
L
I
/
M
I
L
I
M
I
L
A
0
5
=
0
0
1
7
0
5
1
8
0
0
8
8
A
/
A
s
t
u
p
n
I
c
i
g
o
L
e
g
a
tl
o
V
t
u
p
n
I
e
l
b
a
n
E
V
H
I
I
N
E
A
n
0
0
3
>
5
.
1
V
V
L
I
2
.
0
t
n
e
r
r
u
C
s
a
i
B
t
u
p
n
I
e
l
b
a
n
E
I
L
I
V
N
E
V
3
.
0
=
3
.
0
A
I
H
I
V
N
E
V
3
.
1
=
7
.
0
Electrical Characteristics (Cont.)
Note:
(1) Guaranteed by design.
Unless specified: V
IN
= V
EN
= 2V, -40
T
A
85C, typical values are at room temperature.
PDF 
ZIP
