Diodes AP8802 - Manual (Page 6)

AP8802
1A LED STEP-DOWN CONVERTER
AP8802
Document number: DS31766 Rev. 9 - 2
6 of 19
www.diodes.com
May 2012
© Diodes Incorporated
Typical Characteristics (T
A
= +25°C, V
IN
= 40V, L = 68µH; unless otherwise stated.)
O
UT
P
UT
CU
R
RE
N
T
D
E
V
IA
T
IO
N
(%
)
INPUT VOLTAGE (V)
Figure. 8 LED Current vs. Input Voltage
6 12 18 48 24 30 36 42
10
8
6
4
2
0
-2
-4
-6
-8
-10
INPUT VOLTAGE (V)
Figure 9. Efficiency vs. Input Voltage
6 12 18 48 24 30 36 42
INPUT VOLTAGE (V)
Figure. 10 Switching Frequency vs. Input Voltage
6 12 18 48 24 30 36 42
SW
IT
C
H
IN
G
F
R
E
Q
U
E
NC
Y
(
1 LED
3 LEDs 5 LEDs
7 LEDs
k
H
z)
500
T = +25°C
R = 0.2
L = 68µH
A
SET
Ω 450
400
350
300
250
200
150
100
50
0
SUPPLY VOLTAGE (V)
Figure. 11 Duty Cycle vs. Input Voltage
6 12 18 48 24 30 36 42
D
U
T
Y
C
Y
C
LE
(%
)
100
90
80
70
60
50
40
30
20
10
0
Fig. 12 Steady State Waveforms
Fig.13 Start-Up Showing LED Current Soft Start