AP8802 Diodes, Inc., AP8802 Datasheet - Page 10

• Manufacturer Part Number: AP8802
• Description: 1a Led Step-down Converter
• Manufacturer: Diodes, Inc.

Application Information
Capacitor Selection
The small size of ceramic capacitors makes them ideal for AP8802 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 2.2μF input capacitor is sufficient for most intended applications of AP8802.
A 4.7μF input capacitor is suggested for application with an input voltage equal or higher than 40V.
Diode Selection
Schottky diodes, e.g. B2100 or B1100, with their low forward voltage drop and fast reverse recovery, are the
ideal choice for AP8802 applications.
PWM Dimming
A Pulse Width Modulated (PWM) signal with a max resolution of 8bit, can be applied to the CTRL pin to
change the output current to a value above or below the nominal average value set by resistor RSET. To
achieve this resolution the PWM frequency has to be lower than 500Hz.
Thermal Considerations
The graph below in figure 8, gives details for power derating. This assumes the device to be mounted on a
25x25mm PCB with 1oz copper standing in still air.
Package Selection
The device comes with a wide selection of packages. The suggested package is able to provide a case
temperature below 70˚C (with an ambient temperature of 25˚C) for the combination of input voltage and load
requested.
AP8802 Rev. 3
DS31766
2.6
2.4
2.2
1.8
1.6
1.4
1.2
0.8
0.6
0.4
0.2
2
1
0
0
SOP-8L - EP
25
SOP-8L
Figure 8: AP8802 derating curves
(Continued)
A mbient Temperature (D eg C )
www.diodes.com
DFN3030-10
Maximum Power Dis sipation
50
10 of 16
75
100
1A LED Step-down Converter
125
©
AP8802
Diodes Incorporated
MARCH 2009