Ap8800, Application information – Diodes AP8800 User Manual
Page 5
AP8800
Document number: DS31764 Rev. 7 - 2
5 of 13
August 2012
© Diodes Incorporated
AP8800
Application Information
(cont.)
Inductor Selection
A 100
μH inductor is recommended for most AP8800 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.
Switching Frequency
47
68
100
470
100
150
470
150
220
220
0
100
200
300
400
500
600
700
0
50
100
150
200
250
300
350
400
450
500
Inductor Value [uH]
Fr
e
q
ue
n
c
y
[k
H
z
]
12V - 1LED
24V - 3 LEDs
28V - 4LEDs
Figure 3 Switching Frequency vs. Supply Voltage, Inductor, and Number of LEDs
Capacitor Selection
The small size of ceramic capacitors makes them ideal for AP8800 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 1
μF input capacitor is sufficient for most intended
applications of AP8800.
Diode Selection
Schottky diode, e.g. B140, with their low forward voltage drop and fast reverse recovery, is the ideal choice for AP8800 applications.
Miscellaneous
To ensure optimal performance, RSVD pin should be connected to the GND pin with the shortest trace length.