LED2000DR STMicroelectronics, LED2000DR Datasheet - Page 20

• Manufacturer Part Number: LED2000DR
• Description: Current & Power Monitors & Regulators 3A monolithic Conv 850kHz Synch
• Manufacturer: STMicroelectronics

Specifications of LED2000DR

• Rohs: yes
• Product: Current Regulators
• Supply Voltage - Max: 14.7 V
• Supply Voltage - Min: 14.1 V
• Input Voltage Range: 14.1 V to 14.7 V

Application notes
6.6.1
20/40
Figure 12. LED current falling edge operation
Dimming frequency vs. dimming depth
As seen in
system bandwidth (T
The dimming performance depends on the minimum current pulse shape specification of
the final application. The ideal minimum current pulse has rectangular shape, however, it
degenerates into a trapezoid or, at worst, into a triangle, depending on the ratio (T
T
Equation 19
The small signal response in
Equation 20
Assuming the minimum current pulse shape specification as:
Equation 21:
it is possible to calculate the maximum dimming depth given the dimming frequency or vice
versa.
FALL
T
)/ T
T
RISE
FALL
T
-------------------------------------------- - 1
RISE
DIM
rec
Section
T
.
DIM
20 s
+
tan
5 s
T
FALL
gle
T
RISE
6.6, the LEDs current rising and falling edge time mainly depends on the
«
RISE
+
T
) and the selected output capacitor value (T
FALL
Figure 11
Doc ID 023432 Rev 3
=
0.5
T
-------------------------------------------- -
RISE
trapezoid
T
T
MIN_PULSE
DIM
and
+
T
FALL
Figure 12
1
=
0.5
is considered as an example.
D
MIN
T
-------------------------------------------- -
RISE
T
DIMMING
triangle
T
DIM
+
T
FALL
RISE
and T
=
1
FALL
RISE
LED2000
).
AM12903v1
+