sc4540 Semtech Corporation, sc4540 Datasheet - Page 5

• Manufacturer Part Number: sc4540
• Description: High Ei Ciency Boost Converter For Up To 10 Leds
• Manufacturer: Semtech Corporation

Typical Characteristics
All data taken with V
9 0
8 8
8 6
8 2
8 0
9 0
8 8
8 6
8 4
8 2
8 0
9 0
8 6
8 2
7 8
7 4
7 0
8 4
4 .5
4 .5
1 0
V
IN
= 8.4 V
V
IN
= 1 2V
OUT
Effi ciency versus Input Voltage
Effi ciency versus Input Voltage
6 .0
6 .0
= 26.5V (8 white LEDs), R
V
1 5
IN
= 7.2 V
V
L E D E fficie n cy
O U T
Effi ciency vs. I
E fficie n cy
7 .5
7.5
I
B L
V
1 0 m A
3 0 m A
2 0 m A
V
IN
IN
2 0
(m A )
(V )
(V )
ISET
9 .0
9 .0
= 5.76kΩ (I
BL
2 5
1 0 .5
1 0.5
OUT
V
IN
= 20mA), V
= 5.0 V
1 2 .0
1 2 .0
3 0
IN
= 7.2V, L = 56μH, and effi ciency (η) = P
-0.5
-1.5
-2.5
-3.5
3 .5
2 .5
1 .5
0 .5
9 0
8 6
8 2
7 8
7 4
7 0
9 0
8 8
8 2
8 6
8 4
8 0
4 .5
2 0
2 0
6 L E D s
8 L E D s
Normalized I
Effi ciency versus Output Voltage
Effi ciency versus Input Voltage
6.0
2 2
2 2
V
1 0 L E D s
V
IN
IN
= 7 .2V
= 1 2 V
LED
/P
IN
7 .5
BL
2 4
2 4
unless otherwise noted.
versus Output Voltage
V
V
V
V
IN
IN
O U T
V
O U T
= 5 .0V
IN
= 8 .4 V
(V )
(V )
(V )
9 .0
2 6
2 6
V
V
IN
IN
= 1 2V
= 5 .0 V
SC4540
1 0 .5
2 8
2 8
V
V
IN
IN
= 8 .4 V
= 7 .2 V
1 2 .0
3 0
3 0
5 5