Step-Up DC/DC Converters for
White LED Backlight Applications
Typical Characteristics
Efficiency vs. LED Current
(4 White LEDs; R
BALLAST
= 30.1Ω)
Ω
85
84
83
AAT1231/1231-1
Efficiency vs. LED Current
(5 White LEDs; R
BALLAST
= 30.1Ω)
Ω
V
IN
= 5V
Efficiency (%)
82
81
80
79
78
77
76
75
Efficiency (%)
83
82
81
80
79
78
77
2
4
6
8
10
12
14
16
18
20
V
IN
= 5V
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 3.6V
V
IN
= 4.2V
2
4
6
8
10
12
14
16
18
20
LED Current (mA)
LED Current (mA)
Efficiency vs. LED Current
(6 White LEDs; R
BALLAST
= 30.1Ω)
Ω
81
80
84
(12 White LEDs; R
BALLAST
= 30.1Ω)
Ω
83
82
Efficiency vs. LED Current
Efficiency (%)
Efficiency (%)
79
78
77
76
75
74
73
2
V
IN
= 5V
81
80
79
78
77
76
75
74
V
IN
= 5V
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 3.6V
4
6
8
10
12
14
16
18
20
2
4
6
8
10
12
14
16
18
20
LED Current (mA)
LED Current (mA)
Shutdown Current vs. Input Voltage
(EN = GND)
1.0
700
Feedback Voltage vs. Temperature
(R
BALLAST
= 30.1Ω)
Ω
Feedback Voltage (mV)
Shutdown Current (µA)
0.8
0.6
0.4
0.2
0.0
2.7
600
500
400
300
200
100
0
-40
-15
10
35
60
85
85°C
25°C
-40°C
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Temperature (°C)
1231.2007.01.1.2
5
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
