www.austriamicrosystems.com Revision 1.5 9 - 13
AS1101/AS1102/AS1103/AS1104
Data Sheet - Application Information
8 Application Information
Figure 19. Typical Application Diagrams
Setting the LED Current
The current going into the LEDs is approximately OCMR times greater then the current ISET. LED current is controlled
by V
SET and RSET (see Figure 19) according to the formula:
ILED = OCMR x (VSET - VCTRL)/RSET (EQ 1)
For VSET = 3V and a specific LED current, the value of RSET can be determined using the graphs shown in Figure 9,
Figure 10, and Figure 11 on page 7. For any other option, the value of I
SET can be determined using the graph in
Figure 3 on page 6.
Note: LED brightness can also be adjusted by driving pin ENABLE or pin CTRL with a PWM signal.
4 Diode Control with Enable
3 Diode Control with Enable
AS1103
4 Diode Control
V
IN
AS1101
ISET
2 Diode Control with Enable
V
IN
RSET
ENABLE
VSET
(3V)
VSAT
GND
GND
CTRL
I3/I4
I1/I2
ON
I
SET
RSET
VSET
(3V)
CTRL
VSATI1 I2 I3 I4
AS1102
ISET
VIN
RSET
ENABLE
VSET
(3V)
GND
CTRL
ON
VSATI1 I2 I3
AS1104
VIN
GND
VSATI1 I2 I3 I4
ISET
RSET
ENABLE
VSET
(3V)
CTRL
ON