CAT4004 Datasheet, PDF (7/10 Pages) Catalyst Semiconductor – 4-Channel Constant Current LED Driver with EZDi TM

CAT4004
Table 5. PIN DESCRIPTIONS
Pin #
Name
Function
1
EN/DIM Device enable (active high) and dimming control
2
GND
Ground reference
3
LED1
LED1 cathode terminal
4
LED2
LED2 cathode terminal
5
LED3
LED3 cathode terminal
6
LED4
LED4 cathode terminal
7
RSET
RSET external LED mirror gain 128
8
VIN
Device supply input, connect to battery or supply
TAB
TAB
Connect to GND on the PCB
Pin Function
VIN is the supply pin for the device logic. 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 2.5 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.
EN/DIM is the enable and 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 EN/DIM is initially
taken high, the device becomes enabled and all LED
currents are set to the full scale according to the resistor
R_SET. To place the device into “zero current” shutdown
mode, the EN/DIM pin must be held low for at least 1.5 ms.
LED1 to LED4 provide the internal regulated current for
each of the LED cathodes. There pins enter a high
impedance zero current state whenver the device is placed
in shutdown mode.
RSET is connected to the resistor (R_SET) to set the full scale
current for the LEDs. The voltage at this pin is regulated to
0.6 V. The ground side of the external resistor should be star
connected back to the GND of the PCB. In shutdown mode,
RSET beomes high impedance.
GND is the ground reference for the device. The pin must be
connected to the ground plane on the PCB.
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.
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