Four-Channel Backlight Driver with Dual LDOs
Typical Characteristics
C
IN
= C
O1
= C
O2
= 2.2µF, C
1
= C
2
= 1.0µF, C
BP
= 0.1µF; T
A
= 25°C, unless otherwise noted. Typical values are
at T
A
= 25°C and V
IN
= 3.6V.
AAT2845
Backlight Efficiency vs. Supply Voltage
100
90
Turn-On to 1X Mode
(V
IN
= 4.2V; 20mA/ch Load)
EN/SET
(2V/div)
V
OUT
(2V/div)
Efficiency (%)
80
70
60
50
40
30
20mA/ch
1mA/ch
14.7mA/ch
V
SINK
(1V/div)
I
IN
(100mA/div)
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
Supply Voltage (V)
Time (100µs/div)
Turn-On to 1.5X Mode
(V
IN
= 3.5V; 20mA/ch Load)
EN/SET
(2V/div)
V
OUT
(2V/div)
V
SINK
(1V/div)
I
IN
(200mA/div)
Turn-On to 2X Mode
(V
IN
= 2.8V; 20mA/ch Load)
EN/SET
(2V/div)
V
OUT
(2V/div)
V
SINK
(500mV/div)
I
IN
(500mA/div)
Time (100µs/div)
Time (100µs/div)
Turn-Off from 1.5X Mode Backlight
(30mA/ch; Data 1)
EN
(2V/div)
V
DIODE
(2V/div)
I
IN
(200mA/div)
Time (100µs/div)
6
2845.2006.12.1.0
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
