CAT32

http://onsemi.com

2

Typical Application Circuit

Figure 1. Li−Ion Driver for Four High−Brightness White LEDs

15 mA

4

1.50 kW

TSOT−23 Pin Numbers

6.8 mH

2

3

1

6

5

SW

VIN

RSET

D1

C2

1 mF

C1

4.7 mF

VIN

2.7 V

to

4.2 V

PWM

DIMMING

CONTROL

CAT32

LED

GND

SHDN

C1: Taiyo Yuden JMK212BJ475

C2: Taiyo Yuden EMK212BJ105

D1: Zetez ZHCS400

L1: Sumida CLQ4D106R8

(Panasonic ELJEA6R8)

Table 1. PIN DESCRIPTION

Pin Number

SOT23

Pin Number

TDFN

Name

Function

1

8

SW

Switch pin. This is the drain of the internal power switch. For minimum EMI, min-

imize the trace area connected to this pin.

2

5

GND

Ground pin. Connect pin 2 to ground.

3

6

LED

LED (cathode) connection pin.

4

4

RSET

RESET pin. A resistor connected from pin 4 to ground sets the LED current. This

pin is also used to dim the LEDs.

5

3

SHDN

Shutdown pin.

6

2

VIN

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

4.7 mF capacitor mounted close to the pin is recommended.

−

1

Power

Ground

Power Ground