CAT37_08 Datasheet, PDF (9/13 Pages) Texas Instruments – CMOS White LED Driver Boost Converter

TYPICAL APPLICATION CIRCUITS
VIN
3V to 4.2V
Two LEDs with DC Level Dimming Control
L1
6.8µH
D1
C1
1µF
5
VIN
V_DC
Dimming
1
SW
18k
CAT37
4
SHDN
1k
FB ³
GND
2
C2
1µF
15mA
R1
6.34kΩ
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
18k
CAT37
4 _SHDN
1k
FB ³
C2
1µF
15mA
GND
2
R1
6.34kΩ
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
C2
1µF
5
1
10k
1µF
VIN
SW
0.1µF
CAT37
4 _SHDN
GND
2
18k
FB ³
1k
15mA
R1
6.34kΩ
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]
© Catalyst Semiconductor, Inc.
9
Characteristics subject to change without notice
Doc. No. MD-5005 Rev. T