ELM185xB Laser Diode Driver
circuit (5)
ELM7SU04BW
A2
ELM742B
ELM33405CA
R1
100k A1
R2
100k
U1
V1
5V
R3
100k
+
M1
-
+
2.5V
0.9V
U2
R4
68k
-
C1
+
C3
�
0.1
�
10
U3
R8
33k
-
+
0.1V
R5
2.2k
D2
MD
D1
LD
VCC
KLD
ELM185xB
AMD
R6
3k
GND
ILM
CMP
R7
2.2
C2
3300p
■Application circuit example 4 (white LED constant current drive circuit)
Example of application of ELM185xBA as LED constant current drive current is shown as circuit (6).
This circuit is white LED drive circuit which is driven by constant current with external resistance of ILM.
Since the voltage limit of KLD can reach 18V, it is possible to design several LEDs in series connection. The
VCC voltage is controlled to be constant by internal Zener diode of ELM185xB.
circuit (6)
R1
4.7k
D3
C1
White LED
V1
+
D2
D1
ꢀ
1
12V
VCC
KLD
R2
100k
ELM185xB
AMD
W1
Switch
GND
ILM
R7
CMP
C2
4.7
�
10n
This circuit is designed by 3 series-connected white LEDs with power of 12V.
In this circuit, AMD is not used to control light feedback, but on/off only. Current control, which is constant
current type, is monitored by the voltage of ILM. Capacitors of 0.1μF-0.01μF for anti-oscillation are connected
to CMP. Resistance of R7 is set by constant current value; it will be 34mA under 4.7Ω. This value is calculated
by the formula that Iout=0.16/R7. The power of ELM185xB will be lowered from 12V to 7V by R1 and internal
Zener. Light will be turned on when the switch of W1 is ON, and be off when it is OFF.
10 - 8
ELM-TECH [ ELM Technology Corporation ]
