CAT3603

http://onsemi.com

7

TYPICAL CHARACTERISTICS

Figure 20. Foldback Current Limit

OUTPUT CURRENT (mA)

500

400

300

200

100

0

0

1

2

3

4

5

1x Mode

Table 4. PIN DESCRIPTION

Pin #

Name

Function

1

LED1

LED1 cathode terminal (if not used, connect to VOUT) (Note 2)

2

LED2

LED2 cathode terminal (if not used, connect to VOUT) (Note 2)

3

LED3

LED3 cathode terminal (if not used, connect to VOUT) (Note 2)

4

RSET

The LED output current is set by the current sourced out of the RSET pin

5

EN

Device enable (active high)

6

VOUT

Charge pump output connected to the LED anodes

7

VIN

Supply voltage

8

C1+

Bucket capacitor 1 terminal

9

C1−

Bucket capacitor 1 terminal

10

C2−

Bucket capacitor 2 terminal

11

C2+

Bucket capacitor 2 terminal

12

GND

Ground Reference

TAB

Connect to GND on the PCB

2. LED1, LED2, LED3 pins should not be left floating. They should be connected to the LED cathode, or tied to VOUT pin if not used.

Pin Function

VIN is the supply pin for the charge pump. A small 1

mF

ceramic bypass capacitor is required between the VIN pin

and ground near the device. The operating input voltage

range is from 3.0 V to 5.5 V.

EN is the enable control logic input for all LED channels.

Guaranteed levels of logic high and logic low are set at 1.3 V

and 0.4 V respectively.

RSET pin is regulated at 1.2 V. An external resistor RSET

connected from the RSET pin to GND sets the LED current.

VOUT is the charge pump output that is connected to the

LED anodes. A small 1

mF ceramic bypass capacitor is

required between the VOUT pin and ground near the device.

GND is the ground reference for the charge pump. The pin

must be connected to the ground plane on the PCB.

C1+, C1− are connected to each side of the 1

mF ceramic

bucket capacitor C1.

C2+, C2− are connected to each side of the 1

mF ceramic

bucket capacitor C2.

LED1 to LED3 provide the internal regulated current for

each of the LED cathodes. These pins enter a high

impedance, zero current state whenever the device is placed

in shutdown mode. In applications using less than three

LEDs, all unused channels should be wired directly to

VOUT. This ensures the channel is automatically disabled

dissipating less than 200

mA.

TAB is the exposed pad underneath the package. For best

thermal performance, the tab should be soldered to the PCB

and connected to the ground plane.