Step-Up DC/DC Converters for
White LED Backlight Applications
Typical Characteristics
AAT1231 Soft Start with S
2
Cwire
(6 White LEDs; V
FB
= 0.6V)
Enable Voltage (top) (V)
Feedback Voltage (middle) (V)
Enable Voltage (top) (V)
Feedback Voltage (middle) (V)
AAT1231/1231-1
AAT1231 Soft Start
(6 White LEDs; V
FB
= 0.3V)
Inductor Current (bottom) (A)
Inductor Current (bottom) (A)
2.5V
0V
0.4
0.2
0
2
1
0
2.5V
0V
0.2
0
2
1
0
Time (100µs/div)
Time (50µs/div)
AAT1231-1 Soft Start with S
2
Cwire
(6 White LEDs; V
FB
= 0.3V)
Enable Voltage (top) (V)
Feedback Voltage (middle) (V)
AAT1231-1 Soft Start
(6 White LEDs; V
FB
= 0.6V)
Inductor Current (bottom) (A)
Enable Voltage (top) (V)
Feedback Voltage (middle) (V)
Inductor Current (bottom) (A)
2.5V
0.6
0.4
0.2
0
1
0
0V
2.5V
0.6
0.4
0.2
0
1
0
0V
Time (100µs/div)
Time (50µs/div)
Transition of LED Current
(6 White LEDs; SEL = Low; I
LED
= 13.3mA to 6.6mA)
Transition of LED Current
(6 White LEDs; SEL = Low; I
LED
= 3.3mA to 13.3mA)
Feedback Voltage (bottom) (V)
Feedback Voltage (bottom) (V)
Output Voltage (top) (V)
22
20
18
0.4
0.3
0.2
0.1
0.0
Output Voltage (top) (V)
22
20
18
0.4
0.3
0.2
0.1
0.0
Time (20µs/div)
Time (20µs/div)
1231.2007.01.1.2
7
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
