MP3204 – 6V, 1.3MHz WHITE LED DRIVER

MP3204 Rev. 1.3

www.MonolithicPower.com

5

9/23/2005

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TM

APPLICATION INFORMATION

OFF ON

MP3204

2.5V to 6V

LED1

LED2

LED3

MP3204_F02

CMDSH-3

IN

EN

5

3

4

61

2

GND

OV

FB

SW

Figure 2—Driving 3 White LEDs

A typical application circuit can be seen in

Figure 2. The 3 white LEDs can be driven from

a voltage supply range of 2.5V to 6V at an

output current of 20mA. A 0.22µF output

capacitor is sufficient for most applications but

an output capacitor of up to 1µF may be used.

A 22µH inductor with low DCR (inductor

resistance) is recommended for improved

efficiency.

A

1µF

ceramic

capacitor

is

recommended for the input capacitance in the

real system. Schottky diodes have fast recovery

times and a low forward voltage and are also

recommended. Schottky diodes with ratings of

100mA to 200mA are sufficient for use with the

MP3204. The switching characteristics during

normal operation can be seen in Figure 3. The

MP3204 has internal soft-start to limit the

amount of current through VIN at startup and to

also limit the amount of overshoot on the

output. The current limit is increased by a fourth

every 40µs, giving a total soft start time of

120µs.

(AC COUPLED)

50mV/div.

5V/div.

100mA/div.

MP3204_F03

Figure 3—Steady-State Operation