CAT3604
4-Channel Regulated Charge Pump White LED Driver
FEATURES
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Drives individually up to 4 LEDs
Output current up to 30mA per LED
Digital control On/Off of each LED
Compatible with supply voltage of 3V to 5.5V
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Automatic short circuit detect/disable
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High-frequency Operation at 1MHz
Low value ceramic capacitors
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"604" compatible pinout
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Soft start and current limiting
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Thin QFN 16-lead package, 4x4mm, 0.8mm
max height
Power efficiency up to 93%
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2 modes of operation 1x and 1.5x
APPLICATIONS
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Color LCD and keypad Backlighting
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Cellular Phones
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Handheld Devices
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Digital Cameras
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PDAs
Portable MP3 players
DESCRIPTION
The CAT3604 is a charge pump operating in either
1x (LDO) mode or 1.5x fractional mode regulating
current through each of the 4 LED pins. Operation
at a fixed high frequency of 1MHz typical allows the
use of very small value ceramic capacitors.
The CAT3604 drives white light-emitting diodes
(LEDs) connected in parallel and provides tightly
matched regulated current to achieve uniformity of
brightness in LCD backlighting applications. An
external resistor R
SET
controls the output current
level. LED currents of up to 30mA are supported
over a range of input supply voltages from 3V to
5.5V, making the device ideal for battery-powered
applications.
LED dimming can be accomplished by several
methods including using a DC voltage to set the
R
SET
pin current, applying a PWM signal on the
Control signals, or adding a switched resistor in
parallel with R
SET
. The Enable input pin allows the
device to be placed in power-down mode with
"zero” quiescent current.
The CAT3604 features short circuit and overcurrent
limiting protection. The device is available in a 16-
lead thin QFN package with a max height of 0.8mm.
TYPICAL APPLICATION
C1+
VIN
Battery
+
-
VIN
3V to 4.2V
EN
CIN
Control 0
Control 1
Control 2
EN
CTR0
CTR1
CTR2
RSET
GND
RSET
C1- C2+
C2-
VOUT
COUT
CAT3604
LED1
LED2
LED3
LED4
20mA
© 2005 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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Doc. No. 5008, Rev. I
CATALYST [ CATALYST SEMICONDUCTOR ]
