CAT37 Datasheet, PDF (9/11 Pages) Catalyst Semiconductor – CMOS White LED Driver Boost Converter

CAT37
TYPICAL APPLICATION CIRCUITS
3 V to 4.2 V
VIN
C1
1 mF
L1
6.8 mH
D1
V_DC
Dimming
5
1
VIN
SW
180 kW
90
85
C2
80
1 mF
75
VIN = 3.6 V
VIN = 3.0 V
CAT37
15 mA
4 _SHDN
3 ^{10 kW}
FB
70
GND
2
R1
6.34 W
65
60
0
5
10
15
20
25
30
LED CURRENT (mA)
Figure 17. Two LEDs with DC Level Dimming Control
Figure 18. Efficiency − Two LEDs
3 V to 4.2 V
L1
6.8 mH
D1
90
VIN
85
C1
1 mF
5
V_DC
Dimming
1
C2
80
1 mF
VIN
SW
75
180 kW
CAT37
15 mA
4
3 ^{10 kW}
70
SHDN
FB
VIN = 3.6 V
VIN = 3.0 V
GND
2
R1
6.34 W
65
60
0
5
10
15
20
25
30
LED CURRENT (mA)
Figure 19. Three LEDs with DC Level Dimming Control
Figure 20. Efficiency − Three LEDs
3 V to 4.2 V
VIN
L1
6.8 mH
D1
PWM
C1
1 mF
5
VIN
10 kW
1
SW
0.1 mF
CAT37
4 _SHDN
GND
2
180 kW
3
FB
10 kW
R1
6.34 W
C2
1 mF
15 mA
Figure 21. Four LEDs with PWM Dimming Control
90
85
VIN = 3.6 V
80
VIN = 3.0 V
75
70
65
60
0
5
10
15
20
25
30
LED CURRENT (mA)
Figure 22. Efficiency − Four LEDs
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