CAT3644
4-Channel Ultra High Efficiency Quad-Mode™
LED Driver
FEATURES
High efficiency 1.33x charge pump
Quad-mode charge pump: 1x, 1.33x, 1.5x, 2x
Drives up to 4 LEDs at 25mA each
1-wire EZDim™ LED current programming
Power efficiency up to 92%
Low noise input ripple in all modes
“Zero” current shutdown mode
Soft start and current limiting
Short circuit protection
Thermal shutdown protection
3mm x 3mm, 16-lead TQFN package
DESCRIPTION
The CAT3644 is a high efficiency quad-mode
fractional charge pump that can drive up to four LEDs
programmable by a one wire digital interface. The
inclusion of a 1.33x fractional charge pump mode
increases device efficiency by up to 10% over tradi–
tional 1.5x charge pumps with no added external
capacitors.
Low noise input ripple is achieved by operating at a
constant switching frequency which allows the use of
small external ceramic capacitors. The multi-fractional
charge pump supports a wide range of input voltages
from 2.5V to 5.5V.
The EN/DIM logic input functions as a chip enable and
a digital dimming interface for current setting of all
LEDs. Six different current ratios are available via the
interface.
The device is available in the tiny 16-lead TQFN
3mm x 3mm package with a max height of 0.8mm.
The 1.33x charge pump with two fly capacitors is a
patent pending architecture exclusive to Catalyst
Semiconductor.
Package
Marking
(1)
APPLICATION
LCD Display Backlight
Cellular Phones
Digital Still Cameras
Handheld Devices
ORDERING INFORMATION
Part
Number
Package
CAT3644HV3-T2 TQFN-16 3x3mm
JAAG
Note:
(1) Matte-Tin Plated Finish (RoHS-compliant)
PIN CONFIGURATION
LED1
16
LED2
LED3
LED4
RSET
1
2
3
4
5
EN/DIM
6
VOUT
7
NC
8
VIN
GND
15
NC
14
NC
13
12
11
10
9
C2-
C2+
C1-
C1+
TYPICAL APPLICATION CIRCUIT
1µF
1µF
V
IN
2.4V
to
5.5V
CIN
1µF
C1+
V
IN
C1- C2+
C2-
V
OUT
White LEDs
V
OUT
C
OUT
1µF
CAT3644
LED1
EN/DIM
RSET
LED2
LED3
GND
LED4
1-Wire
EZDim
TM
Programming
3.8kΩ
20mA
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. 5023, Rev. B
CATALYST [ CATALYST SEMICONDUCTOR ]
