CAT37

9

Doc No. 5005, Rev. S

© 2005 by Catalyst Semiconductor, Inc.

Characteristics subject to change without notice

TYPICAL APPLICATION CIRCUITS

The application diagrams are shown for the SOT23 pin numbers.

Three LEDs with DC Level Dimming Control

Four LEDs with PWM Dimming Control

Efficiency - Three LEDs

60

65

70

75

80

85

90

0

5

10

15

20

25

30

LED CURRENT [mA]

VIN=3.0V

VIN=3.6V

VIN = 3.6V

VIN = 3.0V

Efficiency - Four LEDs

60

65

70

75

80

85

90

0

5

10

15

20

25

30

LED CURRENT [mA]

VIN = 3.0V

VIN = 3.6V

VIN = 3.0V

VIN = 3.6V

Efficiency - Two LEDs

Two LEDs with DC Level Dimming Control

60

65

70

75

80

85

90

0

5

10

15

20

25

LED CURRENT [mA]

VIN=3.0V

VIN=3.6V

VIN = 3.6V

VIN = 3.0V

30

15mA

2

3

1

5

4

SW

VIN

SHDN

D1

VIN

3 V to 4.2 V

CAT37

FB

GND

VDC

Dimming

1k

18k

15mA

2

3

1

5

4

SW

VIN

SHDN

D1

VIN

3 V to 4.2 V

CAT37

FB

GND

VDC

Dimming

1k

18k

15mA

2

3

1

5

4

SW

VIN

SHDN

D1

VIN

3 V to 4.2 V

CAT37

FB

GND

PWM

1k

18k

10k