Application Note
6 of 28
V 1.0
2019-01-23
ILD8150 80 V high side buck LED driver IC with hybrid dimming
Circuit description
2.2.3
Dimming
Input dimming signal is PWM with minimal amplitude V
DIM
with frequency f
DIM_input
. Current accuracy over
dimming is high enough, and so is the feedback speed, that any input voltage change does not affect output
current (no flicker). The IC operates in hybrid dimming mode. The dimming curve is shown in Figure 6, which
eliminates color shift and audible noise. In the range from 12.5 to 100 percent it operates in analogue dimming
mode as shown in Figure 5, and from 0.5 to 12.5 percent in PWM mode as shown in Figure 4, with fixed output
frequency f
out
.
I
LED,AVG
time [s]
I
OUT
[A]
1/f
OUT
t
PWM _OUT,ON
Figure 4
PWM dimming
I
LED,AVG
time [s]
I
OUT
[A]
1/f
SW
t
ON
t
OFF
I
LED,AVG
Figure 5
Analog dimming
100 x I
out
/I
ref
[%]
D
PWM _IN
[%]
0.5
12.5
12.5
100
100
0.5
Analog dim ming
Hybrid di mming
Figure 6
Hybrid dimming curve
