 English |
|
|
|
|
|
|
|
| AME5142 Datasheet, PDF (8/18 Pages) Analog Microelectronics – White LED Boost Converter In Tiny Package | |||
| |||
| ◁ |
AME, Inc.
AME5142
White LED Boost Converter
In Tiny Package
n Application Hints
Dimming Control
B. Using a DC Voltage
C. Using a Filtered PWM Signal
Using a variable DC voltage to adjust the brightness
is a popular method in some applications. The dim-
ming control using a DC voltage circuit is shown in
Figure 6. According to the Superposition Theorem,
as the DC voltage increases, the voltage contributed
to V increases and the voltage drop on R2 decreases,
FB
i.e. the LED current decreases. For example, if the
VDC range is from 0V to 3V, the selection of resistors
in Figure 6 sets dimming control of LED current from
20mA to 0mA.
VIN 2.7V to 5.5V
L1
10µH
CIN
4.7µF
IN
SW
VOUT
COUT
1µF
EN AME5142 OVP
GND
R3
5.1K
FB
R4
R2
91K
7.5â¦
VDC Dimming
0V to 3V
The filtered PWM signal can be considered as an adjust-
able DC voltage. It can be used to replace the variable DC
voltage source in dimming control. The circuit is shown in
Figure 7.
VIN 2.7V to 5.5V
L1
10µH
CIN
4.7µF
IN
SW
VOUT
COUT
1µF
EN AME5142 OVP
GND
R3
5.1K
FB
R4
91K
R2
7.5â¦
RDC
10K
CDC
0.1µF
3V
0V
PWM Signal
Figure 7. Dimming Control Using a Filtered PWM Signal
Figure6. Dimming Control Using a DC Voltage
10
Rev. A.01
|
▷ |
German
Russian
Spanish
Italian
Polish
Chinese
Japanese
Korean
French
Portuguese