MAX8759 Maxim Integrated Products, MAX8759 Datasheet - Page 8

• Manufacturer Part Number: MAX8759
• Description: CCFL Backlight Controller
• Manufacturer: Maxim Integrated Products

Low-Cost, SMBus, CCFL Backlight Controller
(Circuit of Figure 1, V
8
350
300
250
200
150
100
100
50
80
60
40
20
0
_______________________________________________________________________________________
50
0
A: VFB, 2V/div
B: COMP, 500mV/div
vs. SMBus BRIGHTNESS SETTING
100
LIMITING AND TIMEOUT
NORMALIZED BRIGHTNESS
OPEN-LAMP VOLTAGE
20
BRIGHTNESS SETTING (%)
DPWM FREQUENCY
150
vs. R
40
R
200ms/div
FREQ
IN
200
FREQ
(kΩ)
= 12V, V
60
250
C: TFLT, 5V/div
MAX8759 toc010
300
80
CC
= V
350
100
DD
A
B
C
, T
A
= +25°C, unless otherwise noted.)
100
80
60
40
20
Typical Operating Characteristics (continued)
SECONDARY SHORT-CIRCUIT PROTECTION
0
8
7
6
5
4
3
0
5
A: ISEC, 2V/div
B: COMP, 1V/div
NORMALIZED BRIGHTNESS
0.2
vs. PWMI DUTY CYCLE
RMS LAMP CURRENT
10
vs. INPUT VOLTAGE
AND TIMEOUT
INPUT VOLTAGE (V)
PWMI DUTY RATIO
0.4
2ms/div
15
0.6
I
I
I
I
LAMP
LAMP
LAMP
LAMP
C: TFLT, 1V/div
20
= 7mA
= 6mA
= 5mA
= 4mA
0.8
MAX8759 toc011
1.0
25
A
B
C
100
6.2
6.1
6.0
5.9
5.8
5.7
5.6
80
70
60
50
40
30
80
60
40
20
0
5
0
5
RMS LAMP CURRENT (I
NORMALIZED BRIGHTNESS
0.4
SWITCHING FREQUENCY
10
10
vs. INPUT VOLTAGE
vs. INPUT VOLTAGE
vs. ALS VOLTAGE
INPUT VOLTAGE (V)
0.8
V
V
ALS
IN
15
15
(V)
(V)
1.2
LAMP
20
20
1.6
= 6mA)
25
2.0
25