CAT4109 Datasheet, PDF (7/12 Pages) ON Semiconductor – 3-Channel Constant-Current RGB LED Driver with Individual PWM Dimming

CAT4109
Table 5. PIN DESCRIPTIONS
Name
Pin Number
PGND
1
GND
2
PWM3
3
PWM2
4
PWM1
5
RSET3
6
RSET2
7
RSET1
8
LED3
9
LED2
10
LED1
11
NC
12
NC
13
NC
14
OE
15
VDD
16
Power Ground.
Ground Reference.
PWM control input for LED3
PWM control input for LED2
PWM control input for LED1
LED current set pin for LED3
LED current set pin for LED2
LED current set pin for LED1
LED channel 3 cathode terminal
LED channel 2 cathode terminal
LED channel 1 cathode terminal
Not connected inside package
Not connected inside package
Not connected inside package
Output Enable input pin
Device Supply pin
Function
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
stays low for a duration longer than t_PWRDWN, the device
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.
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