CAT3649 Datasheet, PDF (9/14 Pages) ON Semiconductor – 6-Channel Quad-Mode LED Driver with 32 Dimming Levels & PWM

CAT3649
Table 5. PIN DESCRIPTION
Pin No
Name
1
C1+
2
C1−
3
C2+
4
C2−
5
GND
6
LED1
7
LED2
8
LED3
9
LED4
10
LED5
11
LED6
12
ADIM
13
PWM
14
CPWM
15
VOUT
16
VIN
TAB
GND
Function
Bucket capacitor 1 Positive terminal
Bucket capacitor 1 Negative terminal
Bucket capacitor 2 Positive terminal
Bucket capacitor 2 Negative terminal
Ground Reference
LED1 cathode terminal.
LED2 cathode terminal.
LED3 cathode terminal.
LED4 cathode terminal.
LED5 cathode terminal.
LED6 cathode terminal.
Analog Dimming Control (Active high).
Pulse width modulation ‘PWM’ (Active high).
Connect a capacitor for filtering the PWM signal.
Charge pump output connected to the LED anodes.
Charge pump input, connect to battery or supply.
Connect to GND on the PCB.
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 2.4 V to 5.5 V. Whenever the input supply falls
below the under−voltage threshold (1.8 V), all the LED
channels are disabled and the device enters shutdown mode.
ADIM is the one wire dimming input for all LED channels.
Levels of logic high and logic low are set at 1.3 V and 0.4 V
respectively. When ADIM first transitions from low to high,
each LED channel current is set to 25 mA. Each subsequent
pulse will decrement the current by about 3% from the full
scale.
PWM is the pulse width modulation input pin. When in
logic high condition, the LED current in all six channels
equals the programmed level set via ADIM. When PWM is
low, the LED current is set to 0 mA. This allows the average
LED current to be programmed by the PWM duty cycle. To
place the device into “zero current” shutdown mode, the
ADIM or PWM pin must be held low for 20 ms typical.
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 ceramic bucket
capacitor C₁.
C2+, C2− are connected to each side of the ceramic bucket
capacitor C₂.
LED1 to LED6 provide the internal regulated current
source for each of the LED cathodes. These pins enter
high−impedance zero current state whenever the device is
placed in shutdown mode.
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.
CPWM is the pin for connecting an external capacitor used
to filter the PWM signal inside the CAT3649.
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