CAT3648
4-Channel Ultra High Efficiency Quad-Mode™
LED Driver with 32 Dimming Levels
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™ 32 linear steps
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 CAT3648 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 setting the current in all
LED channels. The 1-wire pulse-dimming interface
supports 32 linear steps from full-scale down to zero
current.
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.
Marking
JAAN
APPLICATION
LCD Display Backlight
Cellular Phones
Digital Still Cameras
Handheld Devices
ORDERING INFORMATION
Part Number
CAT3648HV3-GT2
Qty per Reel
2000
(1)
Notes:
(1) NiPdAu Plated Finish (RoHS-compliant)
PIN CONFIGURATION
(Top View)
TYPICAL APPLICATION CIRCUIT
1µF
1µF
V
IN
2.4V
to
5.5V
CIN
1µF
C1+
VIN
C1- C2+
C2-
VOUT
V
OUT
C
OUT
CAT3648
LED1
EN/DIM
RSET
LED2
LED3
GND
LED4
1µF
1-Wire
EZDim
TM
Programming
3.74kΩ
20mA
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. MD-5031, Rev. A
CAT3648
ABSOLUTE MAXIMUM RATINGS
Parameter
VIN, LEDx, C1±, C2±, EN/DIM voltage
VOUT voltage
Storage Temperature Range
Junction Temperature Range
RECOMMENDED OPERATING CONDITIONS
Parameter
VIN
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-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 Setting
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
Mode Transition Filter Delay
EN/DIM Pin
•
Internal Pull-down Resistor
•
Logic High Level
•
Logic Low Level
Thermal Shutdown
Thermal Hysteresis
Undervoltage lockout (UVLO) threshold
Conditions
1x mode, excluding load
1.33 x mode, excluding load
1.5x mode, excluding load
2x mode, excluding load
V
EN
= 0V
RSET = 3.74kΩ
RSET = 7.50kΩ
(I
LEDAVG
– I
NOMINAL
) / I
NOMINAL
RSET = 4.99kΩ
(I
LED
- I
LEDAVG
) / I
LEDAVG
Min
Typ
1.0
1.7
2.2
2.4
Max
Units
mA
mA
mA
mA
1
20
10
±2
±1.5
0.58
0.6
0.8
5
5
10
1
1.3
50
250
130
400
120
100
1.3
0.4
150
20
1.6
1.8
2.0
0.62
µA
mA
%
%
V
Ω
Ω
Ω
Ω
MHz
MHz
mA
mA
mV
mV
µs
kΩ
V
V
°C
°C
V
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, 1x mode
0.8
1
1.3
1.6
Doc. No. MD-5031, Rev. A
2
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3648
RECOMMENDED EN/DIM TIMING
For 2.4V
≤
V
IN
≤
5.5V, over full ambient temperature range -40ºC to +85ºC.
Symbol
T
LO
T
HI
T
PWRDWN
T
LED
Name
EN/DIM program low time
EN/DIM program high time
EN/DIM low time to shutdown
LED current settling time
Conditions
Min
0.2
0.2
1.5
40
Typ
Max
100
Units
μs
μs
ms
μs
T
HI
EN/DIM
T
LO
T
LED
100%
LED
Current
97% 94%
32 Levels
3%
100%
T
PWRDWN
Shutdown
0%
Shutdown
Figure 1. EN/DIM Digital Dimming Timing Diagram
LED Current Setting
The full scale 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.
Table 1. Resistor RSET and LED Current
Full Scale
LED Current [mA]
2
5
10
15
20
25
30
RSET [kΩ]
37.4
14.7
7.50
4.99
3.74
3.00
2.49
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
3
Doc. No. MD-5031, Rev. A
CAT3648
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-5031, Rev. A
4
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT3648
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
1.2
1.1
1.0
0.9
0.8
0.7
-40
0
40
80
TEMPERATURE [°C]
120
1.33x, 2x Mode
OUTPUT RESISTANCE [Ω] .
Output Resistance vs. Input Voltage
12
1.5x Mode
10
8
6
4
2
0
1.5x
2x
1.33x
1x
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
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
5
Doc. No. MD-5031, Rev. A
PCB设计
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