High Efficiency 1X/1.5X/2X Charge Pump with
PWM Control for White LED Applications
Typical Characteristics
V
IN
= 3.5V, C
IN
= C
CP
= C
1
= C
2
= 1µF, T
A
= 25°C, unless otherwise noted.
1.5X Mode PWM Characteristic
(5kHz at 50% Duty Cycle)
20
AAT3143
PWM Duty Cycle vs. LED Current
LED Current (mA)
V
EN
(2V/div)
I
LED
(20mA/div)
I
IN
(100mA/div)
V
LED
(2V/div)
Time (50µs/div)
18
16
14
12
10
8
6
4
2
0
0
10
20
30
40
50
60
70
80
90
100
100Hz
1kHz
10kHz
Duty Cycle (%)
Line Response
(1X Mode, 4x19mA Load)
Line Response
(1.5X Mode, 4x19mA Load)
V
IN
(0.5V/div)
V
LED
(20mV/div)
V
CP
(0.5V/div)
I
D
(10mA/div)
V
IN
(0.5V/div)
V
LED
(20mV/div)
V
CP
(0.5V/div)
I
D
(10mA/div)
Time (1ms/div)
Time (1ms/div)
Load Characteristics
(1.5X Mode, 4x15mA Load)
90
80
Input Current vs. Input Voltage
(4x10mA)
Input Current (mA)
V
F
(20mV/div)
I
IN
(10mA/div)
V
CP
(20mV/div)
70
60
50
40
30
20
10
0
2.7
3.1
3.5
V
DIODE
= 3.4V
V
DIODE
= 3.0V
3.9
4.3
4.7
5.1
5.5
TIme (1µs/div)
Input Voltage (V)
6
3143.2006.05.1.0
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
