cat4004 Catalyst Semiconductor, cat4004 Datasheet - Page 7

• Manufacturer Part Number: cat4004
• Description: 4-channel Constant Current Led Driver With Ezdim?
• Manufacturer: Catalyst Semiconductor

PIN DESCRIPTIONS
PIN FUNCTION
VIN is the supply pin for the device logic. A small 1μF
ceramic bypass capacitor is required between the VIN
pin and ground near the device. The operating input
voltage range is from 2.5V to 5.5V. Whenever the
input supply falls below the under-voltage threshold
(1.8V), 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 1.3V and 0.4V 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
current” shutdown mode, the EN/DIM pin must be
held low for at least 1.5ms.
LED1 to LED4 provide the internal regulated current
for each of the LED cathodes. There pins enter a high
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
Pin #
TAB
1
2
3
4
5
6
7
8
EN/DIM
RSET
LED1
LED2
LED3
LED4
Name
GND
TAB
VIN
SET
Function
Device enable (active high) and dimming control
Ground reference
LED1 cathode terminal
LED2 cathode terminal
LED3 cathode terminal
LED4 cathode terminal
RSET external LED mirror gain 128
Device supply input, connect to battery or supply
Connect to GND on the PCB
. To place the device into “zero
7
impedance zero current state whenver the device is
placed in shutdown mode.
RSET is connected to the resistor (R
scale current for the LEDs. The voltage at this pin is
regulated to 0.6V. 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.
SET
Doc. No. MD-5024 Rev. B
) to set the full
CAT4004