CAT3644 Datasheet, PDF (1/14 Pages) Catalyst Semiconductor – 4-Channel Ultra High Efficiency Quad-Mode TM LED Driver

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
APPLICATION
„ LCD Display Backlight
„ Cellular Phones
„ Digital Still Cameras
„ Handheld Devices
ORDERING INFORMATION
Part
Number
Package
CAT3644HV3-T2 TQFN-16 3x3mm⁽¹⁾
Package
Marking
JAAG
Note: (1) Matte-Tin Plated Finish (RoHS-compliant)
PIN CONFIGURATION
16 15 14 13
LED2 1
LED3 2
LED4 3
RSET 4
12 C2-
11 C2+
10 C1-
9 C1+
5678
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.
For Ordering Information details, see page 13.
TYPICAL APPLICATION CIRCUIT
1µF
1µF
V_IN
2.4V CIN
to
5.5V ^1µF
1-Wire
EZDim^TM
Programming
3.8kΩ
C1+
V_IN
C1- C2+
C2-
V_OUT
CAT3644
EN/DIM
RSET
GND
LED1
LED2
LED3
LED4
White LEDs
V_OUT
C_OUT
1µF
20mA
© 2007 Catalyst Semiconductor, Inc.
1
Characteristics subject to change without notice
Doc. No. 5023, Rev. B