AP8803

Document number: DS31970 Rev. 5 - 2

5 of 10

www.diodes.com

August 2012

© Diodes Incorporated

AP8803

Inductor Selection

A 33

μH inductor (or higher) is recommended for most AP8803 applications with input voltage at 24V.

Figure 3 displays the resulting switching frequency varying the main circuit parameters: Supply voltage, inductor value and number of LEDs to

be driven.

In particular, the graph in Figure 3 gives values of nominal switching frequency for several values of inductors (L1) in the typical application

circuit shown on Figure 1, for different input voltages and load condition. It can be used to determine the inductor value based on the desired

switching frequency and the input and load conditions.

33

47

68

220

470

100

150

68

33

47

220

100

150

0

100

200

300

400

500

600

0

50

100

150

200

250

300

350

400

450

500

Inductor Value [uH]

12V - 1 LED

24V - 3 LEDs

30V - 5 LEDs

Figure 3 Switching Frequency vs. Supply Voltage, Inductor, and Number of LEDs

Capacitor Selection

The small size of ceramic capacitors makes them ideal for AP8803 applications. X5R and X7R types are recommended because they retain

their capacitance over wider voltage and temperature ranges than other types such as Z5U. A 2.2

μF input capacitor is sufficient for most

intended applications of AP8803.

Diode Selection

Schottky diodes, e.g. B240 or DFLS240L in the proprietary PowerDI123 package, with their low forward voltage drop and fast reverse recovery,

are the ideal choice for AP8803 applications.

In addition, Super Barrier Rectifier devices (as SBR2A40P1) can be used for their enhanced thermal performances.