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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-pad 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-pad TQFN
3mm x 3mm package with a max height of 0.8mm.
®
Catalyst Semiconductor’s Quad-Mode 1.33x charge
pump switching architecture is patented.
APPLICATION
LCD Display Backlight
Cellular Phones
Digital Still Cameras
Handheld Devices
ORDERING INFORMATION
Part Number
CAT3644HV3-T2
CAT3644HV3-GT2
Qty per Reel
2000
(1)
2000
(2)
Marking
JAAG
JAAH
For Ordering Information details, see page 13.
Notes:
(1) Matte-Tin Plated Finish (RoHS-compliant)
(2) NiPdAu Plated Finish (RoHS-compliant)
PIN CONFIGURATION
Top View
LED1
GND
TYPICAL APPLICATION CIRCUIT
1µF
1µF
NC
NC
C1+
CIN
1µF
EN/DIM
RSET
4.02kΩ
GND
V
IN
C1- C2+
C2-
V
OUT
V
OUT
C
OUT
1µF
LED1
LED2
LED3
LED4
20mA
16
LED2
LED3
LED4
RSET
1
2
3
4
5
EN/DIM
15
14
13
12 C2-
11 C2+
10 C1-
9 C1+
V
IN
2.4V
to
5.5V
CAT3644
1-Wire
EZDim
TM
Programming
6
VOUT
7
NC
8
VIN
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. MD-5023, Rev. F
CAT3644
ABSOLUTE MAXIMUM RATINGS
Parameter
V
IN
, LEDx, C1±, C2±, EN/DIM voltage
V
OUT
voltage
Storage Temperature Range
Junction Temperature Range
RECOMMENDED OPERATING CONDITIONS
Parameter
V
IN
Ambient Temperature Range
I
LED
per LED pin
LED Forward Voltage Range
Rating
2.5 to 5.5
-40 to +85
up to 30
1.3 to 4.3
Unit
V
°C
mA
V
Rating
6
7
-65 to +160
-40 to +150
Unit
V
V
°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
NOMINAL
) / I
NOMINAL
RSET = 5kΩ
(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.
MD-5023
Rev.
F
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
LED Current Setting
The nominal LED current is set by the external
resistor connected between the RSET pin and
ground. Table 1 lists standard resistor values for
several LED current settings.
LED current (mA)
2
5
10
15
20
25
30
RSET (kΩ)
40.0
15.8
7.87
5.23
4.02
3.16
2.67
Table 1. Resistor RSET and LED current
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
3
Doc. No. MD-5023, Rev. F
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. MD-5023, Rev. F
4
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
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