CAT32TDI-T3 Datasheet, PDF (9/13 Pages) ON Semiconductor – CMOS White LED Driver

TYPICAL APPLICATION CIRCUITS
VIN
3V to 4.2V
Two LEDs with DC Level Dimming Control
L1
6.8µH
D1
V_DC
C1
Dimming
C2
1µF
5
1
1µF
VIN
SW
180kΩ
CAT37
4
SHDN
FB ³
10kΩ
15mA
GND
2
R1
6.34Ω
CAT37
Efficiency – Two LEDs
90
85
80
75
70
65
60
0
VVININ==33.6.6VV
VVIINN == 33..00VV
5 10 15 20 25 30
LED CURRENT [mA]
Three LEDs with DC Level Dimming Control
L1
6.8µH
D1
VIN
3V to 4.2V
C1
1µF
5
VIN
V_DC
Dimming
1
SW
180kΩ
CAT37
4 _SHDN
10kΩ
FB ³
C2
1µF
15mA
GND
2
R1
6.34Ω
Efficiency –- Three LEDs
90
85
80
75
70
65
60
0
VVININ==3.6V
VIN =V3IN.0=V3.0V
5 10 15 20 25 30
LED CURRENT [mA]
VIN
3V to 4.2V
Four LEDs with PWM Dimming Control
L1
6.8µH
D1
PWM
C1
1µF
5
10kΩ
1
C2
1µF
VIN
SW
0.1µF
CAT37
4 _SHDN
GND
2
180kΩ
FB ³
10kΩ
15mA
R1
6.34Ω
Efficiency – Four LEDs
90
85
VVININ==33..66VV
80
75
VVIINN=33.0.0VV
70
65
60
0
5
10 15 20
25 30
LED CURRENT [mA]
© 2009 SCILLC. All rights reserved.
9
Characteristics subject to change without notice
Doc. No. MD-5005 Rev. V