 English |
|
|
|
|
|
|
|
| MAX1578-MAX1579 Datasheet, PDF (5/13 Pages) Maxim Integrated Products – Complete Bias and White LED Power Supplies for Small TFT Displays | |||
| |||
| ◁ |
Complete Bias and White LED Power Supplies
for Small TFT Displays
Typical Operating Characteristics (continued)
(Circuit of Figure 3, VIN = 3.6V, ILED = 20mA, 4 LEDs, CTRL = IN, TA = +25°C, unless otherwise noted.)
LED CURRENT vs.
DIRECT-PWM DUTY CYCLE
25
BOOST-SWITCHING WAVEFORMS
20
VIN
20mV/div
AC-COUPLED
15
VOUT
200mV/div
AC-COUPLED
10
5
fPWM = 200Hz TO 200kHz
0
0 10 20 30 40 50 60 70 80 90 100
PWM DUTY CYCLE (%)
VLX
400ns/div
10V/div
VCTRL
VIN
AC-COUPLED
BOOST STARTUP AND
SHUTDOWN WAVEFORMS
2V/div
20mV/div
VCTRL
VIN
AC-COUPLED
PWM-DIMMING WAVEFORMS
2V/div
20mV/div
VOUT
IIN
4ms/div
5V/div
0V
100mA/div
VOUT
AC-COUPLED
IIN
40µs/div
50mV/div
20mA/div
LCD BIAS SUPPLY CURRENT
vs. INPUT VOLTAGE
1400
1200
VONBIAS
LCD BIAS STARTUP SEQUENCE
5V/div
1000
VMAIN
5V/div
800
600
VNEG
5V/div
400
200
0
0
VCTRL = 0V
1
2
3
4
5
INPUT VOLTAGE (V)
VPOS
10ms/div
10V/div
_______________________________________________________________________________________ 5
|
▷ |
German
Russian
Spanish
Italian
Polish
Chinese
Japanese
Korean
French
Portuguese