CAT4109

http://onsemi.com

7

Table 5. PIN DESCRIPTIONS

Name

Pin Number

Function

PGND

1

Power Ground.

GND

2

Ground Reference.

PWM3

3

PWM control input for LED3

PWM2

4

PWM control input for LED2

PWM1

5

PWM control input for LED1

RSET3

6

LED current set pin for LED3

RSET2

7

LED current set pin for LED2

RSET1

8

LED current set pin for LED1

LED3

9

LED channel 3 cathode terminal

LED2

10

LED channel 2 cathode terminal

LED1

11

LED channel 1 cathode terminal

NC

12

Not connected inside package

NC

13

Not connected inside package

NC

14

Not connected inside package

OE

15

Output Enable input pin

VDD

16

Device Supply pin

Pin Function

PGND is the power ground reference pin for the device.

This pin must be connected to the GND pin and to the ground

plane on the PCB.

GND is the ground reference pin for the entire device. This

pin must be connected to the ground plane on the PCB.

PWM1 to PWM3 are the control inputs respectively for

LED1, LED2 and LED3 channels. When PWMx are low, the

associated LED channels are turned off. When PWMx are

high, the corresponding channels are turned on, assuming

the OE input is also high. PWMx pins can not be left open

and must be set either to logic high or low.

RSET1 to RSET3 are the LED current set inputs. The

current pulled out of these pins will be mirrored in the

corresponding LED channel with a gain of 400.

LED1 to LED3 are the LED current sink inputs. These pins

are connected to the bottom cathodes of the LED strings.

The current sinks bias the LEDs with a current equal to 400

times the corresponding RSETx pin current. For the LED

sink to operate correctly the voltage on the LED pin must be

above 0.4 V. Each LED channel can withstand voltages up

to 25 V.

OE is the output enable input. When high, all LED channels

are enabled according to the state of their corresponding

PWMx control inputs. When low, all LED channels are

turned off. This pin can be used to turn all the LEDs off

independently of the state of the PWMx inputs. If the OE

enters shutdown mode.

VDD is the positive supply pin voltage for the entire device.

A small 1

mF bypass ceramic capacitor is recommended

between VDD pin and ground near the device.