AS1101/AS1102/AS1103/AS1104
Data Sheet - Application Information
8 Application Information
Figure 19. Typical Application Diagrams
2 Diode Control with Enable
3 Diode Control with Enable
VIN
VIN
I1/I2 VSAT
I3/I4
I1 VSAT
I2
I3
ISET
ISET
VSET
(3V)
VSET
(3V)
CTRL
CTRL
RSET
RSET
AS1101
AS1102
ENABLE
ENABLE
ON
ON
GND
GND
4 Diode Control
4 Diode Control with Enable
VIN
VIN
I1 VSAT I2
I3
AS1103
GND
I4
I1 VSAT I2
I3
I4
ISET
VSET
(3V)
ISET
VSET
(3V)
CTRL
ON
RSET
AS1104
CTRL
RSET
ENABLE
GND
Setting the LED Current
The current going into the LEDs is approximately OCMR times greater then the current ISET. LED current is controlled
by VSET 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 ISET 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.
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