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Revision 1.5

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AS1101/AS1102/AS1103/AS1104

Data Sheet - Ap p lica tio n In fo r m a tio n

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 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.

4 Diode Control with Enable

3 Diode Control with Enable

AS1103

4 Diode Control

VIN

AS1101

ISET

2 Diode Control with Enable

VIN

RSET

ENABLE

VSET

(3V)

VSAT

GND

GND

CTRL

I3/I4

I1/I2

ON

ISET

RSET

VSET

(3V)

CTRL

VSAT

I1

I2

I3

I4

AS1102

ISET

VIN

RSET

ENABLE

VSET

(3V)

GND

CTRL

ON

VSAT

I1

I2

I3

AS1104

VIN

GND

VSAT

I1

I2

I3

I4

ISET

RSET

ENABLE

VSET

(3V)

CTRL

ON