MAX1579 Maxim Integrated Products, MAX1579 Datasheet - Page 5

• Manufacturer Part Number: MAX1579
• Description: Complete Bias and White LED Power Supplies for Small TFT Displays
• Manufacturer: Maxim Integrated Products

(Circuit of Figure 3, V
Complete Bias and White LED Power Supplies
AC-COUPLED
V
V
CTRL
OUT
V
I
IN
IN
1400
1200
1000
800
600
400
200
25
20
15
10
0
5
0
0
0
_______________________________________________________________________________________
IN
10
= 3.6V, I
SHUTDOWN WAVEFORMS
LCD BIAS SUPPLY CURRENT
DIRECT-PWM DUTY CYCLE
1
BOOST STARTUP AND
20 30
vs. INPUT VOLTAGE
PWM DUTY CYCLE (%)
LED CURRENT vs.
INPUT VOLTAGE (V)
2
4ms/div
LED
40 50
f
PWM
= 20mA, 4 LEDs, CTRL = IN, T
3
= 200Hz TO 200kHz
60 70 80 90 100
V
CTRL
4
= 0V
Typical Operating Characteristics (continued)
5
0V
100mA/div
2V/div
20mV/div
5V/div
A
= +25°C, unless otherwise noted.)
for Small TFT Displays
AC-COUPLED
AC-COUPLED
AC-COUPLED
AC-COUPLED
V
V
ONBIAS
V
V
V
CTRL
V
V
V
OUT
MAIN
OUT
V
V
NEG
POS
I
LX
IN
IN
IN
BOOST-SWITCHING WAVEFORMS
PWM-DIMMING WAVEFORMS
LCD BIAS STARTUP SEQUENCE
400ns/div
40µs/div
10ms/div
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10V/div
20mA/div
20mV/div
200mV/div
2V/div
20mV/div
50mV/div
5V/div
5V/div
5V/div
10V/div
5