User guide

AP8801
500mA LED STEP-DOWN CONVERTER
AP8801
Document number: DS31765 Rev. 7 - 2
4 of 14
www.diodes.com
June 2012
© Diodes Incorporated
Typical Characteristics
INPUT VOLTAGE (V)
Figure. 2 Supply Current (not switching) vs. Input Voltage
06055510 15 20 25 30 35 40 5045
0.1
0
0.3
0.2
0.7
0.6
0.9
0.8
0.5
0.4
N
O
N
-SWI
T
C
H
I
N
G
S
U
P
P
L
Y
C
U
R
R
E
N
T
(mA)
AMBIENT TEMPERATURE C)
Figure. 3 V vs. Ambient Temperature
CTRL
-40 125-25 110-10 5 20 35 50 65 9580
1.244
1.252
1.250
1.256
1.254
1.248
1.246
C
T
R
L V
O
L
T
A
G
E (V)
-40 -25 -10 5 20 35 50 65 80 95 110 125
AMBIENT TEMPERATURE (C)
Figure. 4 R vs Ambient Temperature
DS(ON)
1.2
1.0
0.8
0.6
0.4
0.2
0
R
()
DS(ON)
Ω
R RESISTANCE ( )
Figure. 5 LED Current vs. R
SET
SET
Ω
0 0.5 1.5 2.01.0
0
300
250
500
450
50
LED
C
U
R
R
E
N
T
(mA)
400
200
100
350
150
CTRL VOLTAGE (V)
Figure. 6 LED Current vs. V
CTRL
02.50.5 1.0 1.5 2.0
0
400
300
600
500
100
LED
C
U
R
R
EN
T
(mA)
200
R = 0.56
SET
Ω
R = 0.68
SET
Ω
R = 1.33
SET
Ω
CTRL VOLTAGE (V)
Figure. 7 Switching Frequency vs. V
CTRL
02.50.5 1.0 1.5 2.0
0
500
400
800
700
100
SWI
T
C
H
I
N
G
F
R
E
Q
U
E
N
C
Y
(k
H
z)
300
600
200