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.
Efficiency
(100% Duty Cycle, 4x20mA/channel)
100
90
AAT3143
Turn-On to 1X Mode
(V
IN
= 4.2V)
Efficiency (%)
80
70
60
50
40
30
2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2
V
EN
(1V/div)
V
CP
(2V/div)
V
LED
(2V/div)
I
IN
(100mA/div)
Time (50µs/div)
Input Voltage (V)
Turn-On to 1.5X Mode
(V
IN
= 3.5V)
Turn-On to 2X Mode
(V
IN
= 2.7V)
V
EN
(1V/div)
V
CP
(2V/div)
V
LED
(2V/div)
I
IN
(50mA/div)
Time (50µs/div)
V
EN
(1V/div)
V
CP
(2V/div)
V
LED
(2V/div)
I
IN
(50mA/div)
Time (50µs/div)
LED Turn-On Delay
(PWM Frequency = 500Hz)
LED Turn-On Delay
(PWM Frequency = 5kHz)
V
EN
(2V/div)
V
LED
(2V/div)
V
EN
(2V/div)
V
LED
(2V/div)
I
LED
(10mA/div)
I
LED
(10mA/div)
Time (5µs/div)
Time (1µs/div)
3143.2006.05.1.0
5
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
