CAT3626
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9
Table 5. PIN DESCRIPTIONS
Pin # Name Function
1 LEDA1 Cathode terminal of LED A1
2 SDA I
2
C Serial data input/output
3 SCL I
2
C Serial clock input
4 EN Enable input
5 VOUT Charge pump output connected to the LED anodes
6 VIN Supply voltage
7 C1− Bucket capacitor 1 terminal
8 C1+ Bucket capacitor 1 terminal
9 C2− Bucket capacitor 2 terminal
10 C2+ Bucket capacitor 2 terminal
11 GND Ground reference
12 LEDC2 Cathode terminal of LED C2
13 LEDC1 Cathode terminal of LED C1
14 LEDB2 Cathode terminal of LED B2
15 LEDB1 Cathode terminal of LED B1
16 LEDA2 Cathode terminal of LED A2
TAB Connect to Ground on 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 2.2 V to 5.5 V. Whenever the input supply falls
below the undervoltage threshold (2 V), all LEDs channels
will be automatically disabled.
EN is the enable logic input for the driver. Guaranteed levels
of logic high and logic low are set at 1.3 V and 0.4 V
respectively. When EN is initially taken high, the device
becomes enabled and all LED currents remain at 0 mA. To
place the device into zero current shutdown mode, the EN
pin must be held low.
SDA is the I
2
C serial data line. This is a bidirectional line
allowing data to be written into and read from the four
registers in the driver. Registers RegA/B/C set the LED
current in each pair of channels, while RegEn sets the
On/Off state independently of each channel.
SCL is the I
2
C serial clock input.
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.
LEDxx provide the internally regulated current to the six
LED cathodes. These pins enter a high−impedance
zero−current state whenever the device is placed in
shutdown mode. In applications using less than six LEDs,
the unused channels should be disabled through the RegEn
register.
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.
