AS1101/AS1102/AS1103/AS1104
Data Sheet
- A p p l i c a t i o n I n f o r m a t i o n
8 Application Information
Figure 19. Typical Application Diagrams
2 Diode Control with Enable
V
IN
V
IN
3 Diode Control with Enable
I1/I2 V
SAT
I
SET
V
SET
(3V)
R
SET
CTRL
ON
GND
I3/I4
I
SET
V
SET
(3V)
I1 V
SAT
I2
I3
AS1101
R
SET
CTRL
ON
AS1102
GND
ENABLE
ENABLE
4 Diode Control
V
IN
V
IN
4 Diode Control with Enable
I1 V
SAT
I2
I
SET
V
SET
(3V)
R
SET
CTRL
I3
I4
I
SET
V
SET
(3V)
I1 V
SAT
I2
I3
I4
AS1103
GND
R
SET
CTRL
ON
AS1104
GND
ENABLE
Setting the LED Current
The current going into the LEDs is approximately OCMR times greater then the current I
SET
. LED current is controlled
by V
SET
and R
SET
(see
according to the formula:
I
LED
= OCMR x (V
SET
- V
CTRL
)/R
SET
(EQ 1)
For V
SET
= 3V and a specific LED current, the value of R
SET
can be determined using the graphs shown in
Figure 10,
and
Figure 11
on page 7. For any other option, the value of I
SET
can be determined using the graph in
Note:
LED brightness can also be adjusted by driving pin ENABLE or pin CTRL with a PWM signal.
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