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
For Ordering Information details, see page 13.
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
CAT3644
ABSOLUTE MAXIMUM RATINGS
Parameter
V
IN
, LEDx, C1±, C2± voltage
V
OUT
voltage
EN/DIM voltage
Storage Temperature Range
Junction Temperature Range
Lead Temperature
RECOMMENDED OPERATING CONDITIONS
Parameter
V
IN
Ambient Temperature Range
I
LED
per LED pin
Total Output Current
LED Forward Voltage Range
Rating
2.5 to 5.5
-40 to +85
0 to 25
0 to 100
1.3 to 4.3
Unit
V
°C
mA
mA
V
Rating
6
7
6
-65 to +160
-40 to +125
300
Unit
V
V
V
°C
°C
°C
Typical application circuit with external components is shown on page 1.
ELECTRICAL OPERATING CHARACTERISTICS
(over recommended operating conditions unless specified otherwise) V
IN
= 3.6V, EN = High, T
AMB
= 25°C
Symbol
I
Q
I
QSHDN
I
LED-ACC
I
LED-DEV
V
RSET
R
OUT
F
OSC
I
SC_MAX
I
IN_MAX
LED
TH
V
HYS
T
DF
R
EN/DIM
V
HI
V
LO
T
SD
T
HYS
V
UVLO
Name
Quiescent Current
Shutdown Current
LED Current Accuracy
LED Channel Matching
RSET Regulated Voltage
Output Resistance (open loop)
Charge Pump Frequency
Output short circuit Current Limit
Input Current Limit
1x to 1.33x or 1.33x to 1.5x or 1.5x to 2x
Transition Thresholds at any LED pin
1x Mode Transition Hysteresis
Transition Filter Delay
EN/DIM Pin
•
Internal Pull-down Resistor
•
Logic High Level
•
Logic Low Level
Thermal Shutdown
Thermal Hysteresis
Undervoltage lockout (UVLO) threshold
1.6
1x mode
1.33x mode, V
IN
= 3V
1.5x mode, V
IN
= 2.7V
2x mode, V
IN
= 2.4V
1.33x and 2x mode
1.5x mode
V
OUT
< 0.5V
V
OUT
> 1V
Conditions
1x mode, no load
1.33 x mode, no load
1.5x mode, no load
2x mode, no load
V
EN
= 0V
I
LEDAVG
/ I
LEDAVG-NOMINAL
(I
LED
- I
LEDAVG
) / I
LEDAVG
0.58
Min
Typ
1.0
1.7
2.2
2.4
±2
±1.5
0.6
0.8
5
5
10
1
1.3
50
250
130
400
500
100
1.3
0.4
150
20
1.8
2.0
0.62
Max
Units
mA
mA
mA
mA
µA
%
%
V
Ω
Ω
Ω
Ω
MHz
MHz
mA
mA
mV
mV
µs
kΩ
V
V
°C
°C
V
1
0.8
1
1.3
1.6
Doc. No. 5023, Rev. B
2
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3644
RECOMMENDED EN/DIM TIMING
For 2.4V
≤
V
IN
≤
5.5V, over full ambient temperature range -40ºC to +85ºC.
Symbol
T
SETUP
T
LO
T
HI
T
PWRDWN
T
LED
Name
EN/DIM setup from shutdown
EN/DIM program low time
EN/DIM program high time
EN/DIM low time to shutdown
LED current settling time
Conditions
Min
10
0.2
0.2
1.5
40
100
Typ
Max
Units
μs
μs
μs
ms
μs
T
SETUP
T
HI
T
PWRDWN
EN/DIM
T
LED
100%
50%
LED
Current
Shutdown
25%
T
LO
100%
12.5% 6.25%
3.12%
Shutdown
Figure 1. EN/DIM Digital Dimming Timing Diagram
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
3
Doc. No. 5023, Rev. B
CAT3644
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
= 3.6V, I
OUT
= 80mA (4 LEDs at 20mA), C
IN
= C
OUT
= C
1
= C
2
= 1μF, T
AMB
= 25°C unless otherwise specified.
Efficiency vs. Input Voltage
100
90
EFFICIENCY [%]
1x
80
70
60
50
40
4.5
4.0
3.5
3.0
2.5
INPUT VOLTAGE [V]
2.0
2x
V
F
= 3.3V
1.33x
1.5x
EFFICIENCY [%]
100
90
80
70
60
50
40
4.2
4.0 3.8 3.6 3.4 3.2
INPUT VOLTAGE [V]
3.0
Efficiency vs. Li-Ion Voltage
V
F
= 3.3V
1x
1.33x
Quiescent Current vs. Input Voltage
4.0
QUIESCENT CURRENT [mA]
QUIESCENT CURRENT [mA]
Quiescent Current vs. Temperature
4.0
V
F
= 3.3V
3.0
2.0
1.0
LEDs Off
0.0
5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0
INPUT VOLTAGE [V]
2x
3.0
1.5x
2.0
1.33x
1x
1.0
0.0
-40
0
40
80
TEMPERATURE [°C]
120
LED Current Change vs. Input Voltage
10
8
6
4
2
0
-2
-4
-6
-8
-10
LED CURRENT VARIATION [%] .
LED CURRENT VARIATION [%] .
LED Current Change vs. Temperature
10
8
6
4
2
0
-2
-4
-6
-8
-10
-40
0
40
80
TEMPERATURE [°C]
120
V
F
= 3.3V
V
F
= 3.3V
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
Doc. No. 5023, Rev. B
4
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3644
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
= 3.6V, I
OUT
= 80mA (4 LEDs at 20mA), C
IN
= C
OUT
= C
1
= C
2
= 1μF, T
AMB
= 25°C unless otherwise specified.
Switching Frequency vs. Temperature
SWITCHING FREQUENCY [MHz]
1.3
OUTPUT RESISTANCE [Ω] .
Output Resistance vs. Input Voltage
12
1.2
1.1
1.0
0.9
0.8
0.7
-40
1.5x Mode
10
8
6
4
2
0
1.5x
2x
1.33x
1.33x, 2x Mode
1x
0
40
80
TEMPERATURE [°C]
120
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE [V]
Power Up in 1x Mode
Power Up in 1.33x Mode
Power Up in 1.5x Mode
Power Up in 2x Mode
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
5
Doc. No. 5023, Rev. B
ARM技术
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
