CAT3637
6-Channel Programmable High Efficiency
Quad-Mode™ LED Driver
FEATURES
High efficiency 1.33x charge pump
Quad-Mode charge pump: 1x, 1.33x, 1.5x, 2x
Drives 6 LEDs between 30mA and 0mA each
1-wire EZDim
TM
interface with 2mA step
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
Tiny 3mm x 3mm, 16-pad TQFN package
DESCRIPTION
The CAT3637 is a high efficiency Quad-Mode fractional
charge pump that can drive up to six LEDs program-
mable by a 1-wire digital interface. The inclusion of a
1.33x fractional charge pump mode increases device
efficiency by up to 10% over traditional 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/SET logic input functions as a chip enable and a
digital programming interface for setting the current in the
LED channels. The 1-wire pulse-programming interface
supports 15 linear steps from zero current to 30mA full-
brightness in 2mA steps.
The device is available in a tiny 16-pad TQFN 3 x 3mm
package with a maximum height of 0.8mm.
Catalyst Semiconductor’s Quad-Mode 1.33x, charge pump
switching architecture is patented.
Package
Marking
JAAM
APPLICATIONS
LCD Display Backlight
Cellular Phones
Digital Still Cameras
Handheld Devices
ORDERING INFORMATION
Part Number
CAT3637HV3-GT2
Quantity
per Reel
2000
(1)
Note:
(1) NiPdAu Plated Finish (RoHS-compliant)
16-lead TQFN 3mm x 3mm Package
PIN CONFIGURATION
(top view)
EN/SET
16
LED6
LED5
LED4
LED3
1
2
3
4
5
6
7
8
TYPICAL APPLICATION CIRCUIT
1µF
1µF
15
GND
LED1
14
NC
13
12 C2-
11 C2+
10 C1-
9
C1+
NC
V
IN
2.5V
to
5.5V
C
IN
1µF
C1-
VIN
C1+
C2-
C2+
VOUT
V
OUT
CAT3637
1-Wire
Programming
EN/SET
GND
LED1
LED2
LED3
LED4
LED5
LED6
C
OUT
1µF
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
LED2
VOUT
VIN
1
Doc. No. MD-5033 Rev. A
CATALYST [ CATALYST SEMICONDUCTOR ]
