High Efficiency White LED Drivers
for Backlight and Keypad
Typical Characteristics
Efficiency vs. LED Current
(Group B On; Group A Off)
83
82
84
AAT1235
Efficiency vs. LED Current
(Group B Off; Group A On)
V
IN
= 5V
V
IN
= 5V
Efficiency (%)
83
82
81
80
79
78
77
Efficiency (%)
81
80
79
78
77
76
1.6
3.9
6.2
8.5
10.8
13.1
15.4
17.7
20
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 4.2V
1.6
3.9
6.2
8.5
10.8
13.1
15.4
17.7
20
Output LED Current (mA)
Output LED Current (mA)
Efficiency vs. LED Current
(Group A and B On)
86
85
LED Current Accuracy vs. Supply Voltage
3
2
Efficiency (%)
84
83
82
81
80
79
1.6
V
IN
= 5V
V
IN
= 3.6V
V
IN
= 4.2V
Accuracy (%)
I
B1, B2, A1, A2, A3
1
0
-1
-2
-3
3.9
6.2
8.5
10.8
13.1
15.4
17.7
20
2.7
3.1
3.4
3.8
4.1
4.5
4.8
5.2
5.5
Output LED Current (mA)
Supply Voltage (V)
LED Current vs. Supply Voltage
20.0
19.8
Shutdown Current vs.
Supply Voltage and Temperature
0.7
Shutdown Current (µA)
I
B1
I
A1
LED Current (mA)
0.6
0.5
0.4
0.3
0.2
0.1
0.0
2.7
19.6
19.4
19.2
19.0
18.8
18.6
18.4
2.7
3.1
3.4
25°C
85°C
I
A3
I
B2
I
A2
-40°C
3.1
3.5
3.9
4.3
4.7
5.1
5.5
3.8
4.1
4.5
4.8
5.2
5.5
Supply Voltage (V)
Supply Voltage (V)
1235.2007.02.1.1
5
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
