CAT37

http://onsemi.com

2

Typical Application Circuit

Figure 1. Driver for Four High−Brightness White LEDs

15 mA

6.34 W

L1 6.8 mH

2

3

1

5

4

SW

VIN

D1

C2

1 mF

C1

1 mF

VIN

3 V to 5 V

ON OFF

CAT37

FB

GND

SHDN

C1: Taiyo Yuden JMK212BJ475

C2: Taiyo Yuden EMK212BJ105

L1: Panasonic ELJEA6R8 or equivalent

Table 1. PIN DESCRIPTION

Pin Number

Name

Function

1

SW

Switch pin. This is the drain of the internal power switch. For minimum EMI, minimize the trace area

connected to this pin.

2

GND

Ground pin. Connect pin 2 to ground.

3

FB

LED (cathode) connection pin.

4

SHDN

Shutdown pin.

5

VIN

Input supply pin. This pin should be bypassed with a capacitor to ground. A 1 mF capacitor mounted

close to the pin is recommended.

Table 2. ABSOLUTE MAXIMUM RATINGS

Parameter

Rating

Unit

8

V

SW voltage

20

V

Storage Temperature Range

−65 to +160

°C

Junction Temperature

125

°C

Lead Soldering Temperature (10 secs)

300

°C

ESD Rating – Human Body Model

2000

V

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the

Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect

device reliability.

Table 3. RECOMMENDED OPERATING CONDITIONS

Parameter

Range

Unit

2.5 to 7

V

Ambient Temperature Range

−40 to +85

°C

Inductor L1

6.8 ± 20% typical

mH

Input Capacitor C1

1.0 ± 20% typical

mF

Output Capacitor C2

1.0 ± 20% typical

mF

0 to 20

mA

NOTE: Typical application circuit with external components is shown above.