Rainbow Electronics MAX8759 - Manual (Page 8)

MAX8759
Low-Cost, SMBus, CCFL Backlight Controller
8 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
IN
= 12V, V
CC
= V
DD
, T
A
= +25 °C, unless otherwise noted.)
C
B
A
A: VFB, 2V/div
B: COMP, 500mV/div
OPEN-LAMP VOLTAGE
LIMITING AND TIMEOUT
MAX8759 toc010
200ms/div
C: TFLT, 5V/div
C
B
A
A: ISEC, 2V/div
B: COMP, 1V/div
SECONDARY SHORT-CIRCUIT PROTECTION
AND TIMEOUT
MAX8759 toc011
2ms/div
C: TFLT, 1V/div
30
40
60
50
70
80
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
MAX8759 toc12
V
IN
(V)
SWITCHING FREQUENCY (kHz)
5 15 10 20 25
50
150
100
250
200
300
350
DPWM FREQUENCY
vs. R FREQ
MAX8759 toc13
R FREQ (k Ω)
DPWM FREQUENCY (Hz)
50 150 200 100 250 300 350
3
4
6
5
7
8
RMS LAMP CURRENT
vs. INPUT VOLTAGE
MAX8759 toc14
INPUT VOLTAGE (V)
RMS LAMP CURRENT (mA)
5 15 10 20 25
I LAMP = 7mA
I LAMP = 6mA
I LAMP = 5mA
I LAMP = 4mA
5.6
5.8
5.7
6.0
5.9
6.1
6.2
5 15 10 20 25
RMS LAMP CURRENT (I LAMP = 6mA)
vs. INPUT VOLTAGE
MAX8759 toc15
INPUT VOLTAGE (V)
RMS LAMP CURRENT (mA)
0
20
60
40
80
100
0 0.4 0.2 0.6 0.8 1.0
NORMALIZED BRIGHTNESS
vs. PWMI DUTY CYCLE
MAX8759 toc17
PWMI DUTY RATIO
NORMALIZED BRIGHTNESS (%)
0
20
60
40
80
100
0 0.8 0.4 1.2 1.6 2.0
NORMALIZED BRIGHTNESS
vs. ALS VOLTAGE
MAX8759 toc18
V ALS (V)
NORMALIZED BRIGHTNESS (%)
0
20
60
40
80
100
0 40 20 60 80 100
NORMALIZED BRIGHTNESS
vs. SMBus BRIGHTNESS SETTING
MAX8759 toc16
BRIGHTNESS SETTING (%)
NORMALIZED BRIGHTNESS (%)