Typical Operating Characteristics (continued)

°C, unless otherwise noted.)

Complete Bias and White LED Power Supplies

for Small TFT Displays

_______________________________________________________________________________________

5

PWM-DIMMING WAVEFORMS

AC-COUPLED

AC-COUPLED

2V/div

50mV/div

20mA/div

20mV/div

40

µs/div

0

400

200

800

600

1200

1000

1400

02

3

14

5

LCD BIAS SUPPLY CURRENT

vs. INPUT VOLTAGE

INPUT VOLTAGE (V)

LCD BIAS STARTUP SEQUENCE

5V/div

5V/div

10V/div

5V/div

10ms/div

BOOST STARTUP AND

SHUTDOWN WAVEFORMS

AC-COUPLED

2V/div

5V/div

0V

100mA/div

20mV/div

4ms/div

0

5

10

15

20

25

040 50

20 30

10

60 70 80 90 100

LED CURRENT vs.

DIRECT-PWM DUTY CYCLE

PWM DUTY CYCLE (%)

BOOST-SWITCHING WAVEFORMS

AC-COUPLED

AC-COUPLED

20mV/div

10V/div

200mV/div

400ns/div