Agamem Microelectronics Inc.
PRELIMINARY
AA1700
Constant Current White LED driver
CDS Control for IR LED
Vcc
IN
SP
Vcc
CTL
390Ω
Q2
C1815
Q3
C1815
C8
10uF
R8
4.7KΩ
1
8
ER
CLK
GND
P0
VR1
50K
R7
300Ω
D3
2
3
4
AA1700
7
6
5
R2
CdS Light
Sensitive Resistor
Note:
1.Light striking the surface of the Cds causes a decrease in resistance, while darkness
produces a higher resistance. When the light is bright, Q3 is on and Q2 is off, AA1700
will enter stand-by mode and there is no output current provided. When the light is dark,
Q3 is off and Q2 is on, AA1700 will output current and driver the IR LEDs. If the light Is
gray, the Q2 and Q3 will enter active mode, the impedance of Cds will decide the
collector current of Q3 and also Impact on the Internal impedance of Q2, so the driving
current can be controlled.
2.VR1 is for light sensitive control, the value will decide how darkness of the light source
the IR LEDs will brighten.
©Copyright
Agamem Microelectronics Inc.
8
www.agamem.com.tw
2007/1/22
AGAMEM [ AGAMEM MICROELECTRONIC INC. ]
