AS1340 datasheet(11/17 Pages) AMSCO

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AS1340

Datasheet - Application In form atio n

9.5 LED Power Supply Application

The AS1340 can also be used for driving LEDs. Just simply connect the LEDs between the pins LX and FB. (see Figure 29).

Figure 29. LED Supply Application

The output voltage is adjusted automatically to the required voltage of the LEDs. This voltage depends on the forward voltage (VF) of the used

LEDs and the Feedback Voltage VFB.

Calculate VOUT by:

Note:

The brightness of the LEDs can directly be adjusted by setting the current ILED via the corresponding R2.

Calculate R2 by:

Where:

VFB = 1.25V

n .... number of LED’s

7,9

GND

VCC

Off

AS1340

4.7µH

0.1µF

COUT

1µF

100



SWVIN

SWOUT

POK

0.1µF

ILED

VIN

= 2.7V

to 5.5V

(EQ 3)

VOUT

VF ILED

 n



VFB

(EQ 4)

ILED

VFB

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