CAT4237 Datasheet, PDF (6/13 Pages) Catalyst Semiconductor – High Voltage CMOS Boost White LED Driver

CAT4237
TYPICAL CHARACTERISTICS
(V_IN = 3.6 V, C_IN = 4.7 mF, C_OUT = 0.22 mF, L = 33 mH with 8 LEDs at 20 mA, T_AMB = 25°C, unless otherwise specified.)
35
1.0
30
R_FB = 10 W
25
0.5
R_FB = 15 W
20
R_FB = 20 W
0
15
10
5
0
2.5
3.0
3.5
4.0
4.5
5.0
INPUT VOLTAGE (V)
Figure 10. LED Current vs. Input Voltage
(8 LEDs)
90
−0.5
−1.0
3.0 3.3
3.6
3.9
4.2
4.5
4.8
INPUT VOLTAGE (V)
Figure 11. LED Current Regulation (20 mA)
90
85
VIN = 4.2 V
85
20 mA
15 mA
80
VIN = 3.6 V
80
75
8 LEDs
70
VOUT ~ 27 V at 20 mA
L = 33 mH
65
5
10
15
20
25
30
LED CURRENT (mA)
Figure 12. 8 LED Efficiency vs. Load Current
75
8 LEDs
70 VOUT ~ 27 V at 20 mA
L = 33 mH
65
3.0
3.5
4.0
4.5
5.0
INPUT VOLTAGE (V)
Figure 13. 8 LED Efficiency vs. Input Voltage
90
90
VIN = 4.2 V
VIN = 4.2 V
85
85
VIN = 3.6 V
VIN = 3.6 V
80
80
75
7 LEDs
70
VOUT ~ 23 V at 20 mA
L = 33 mH
65
5
10
15
20
25
30
LED CURRENT (mA)
Figure 14. 7 LED Efficiency vs. Load Current
75
6 LEDs
70
VOUT ~ 20 V at 20 mA
L = 33 mH
65
5
10
15
20
25
30
LED CURRENT (mA)
Figure 15. 6 LED Efficiency vs. Load Current
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