The output current of the unit can also be set by
adjusting the voltage level on the V
ADJ
input to a
value between 0.3V to 1.25V (I
OUT
will vary from
25% to 100% of rated output current). Care must
be taken not to exceed 1.25V on this input, or
the driver may be damaged.
A simple analog circuit using two low cost,
switching regulators is shown at left. Work-
ing from inputs that can range from 15 to 32
VDC,the top regulator (SR
1
) keeps the input to
the LED driver at 12 VDC.
The other regulator (SR
2
), driven off the same
input line maintains the control voltage (for the
V
ADJ
input) at 5 VDC. The resister network of R
1
and R
2
can now be used to set the output cur-
rent level of the LED driver. This level is equal to:
www.micropowerdirect.com
Analog Output Current Control
V
ADJ
=
R
2
X V
CTRL
R
1
+ R
2
In the second circuit, the 5 VDC regulator (SR
2
)
is replaced by the shunt regulator (D
1
) circuit
connected in parallel with the resistor network.
The regulator will maintain the voltage across R
2
and R
3
at 2.5 VDC, insuring that the 1.25 VDC
limit on the V
ADJ
pin will not be exceeded. This
circuit will work for inputs between 7VDC and
approximately 36 VDC. For inputs between 36
VDC and 60 VDC, a zener diode (D
2
) has been
added.
When using the analog control input, the nominal
output current is equal to:
Analog Output Current Control
(7 - 36 VDC IN)
I
NOM
= I
MAX
x
V
ADJ
1.25
The V
ADJ
input should be left open if not used.
Grounding V
ADJ
will shut the unit down. Connect-
ing V
ADJ
to directly to +V
IN
may damage the unit.
Analog Output Current Control
(36 - 60 VDC IN)
Mechanical Dimensions
Pin Connections
Pin
1
15
12
13
24
Color
Black
White
Blue
Yellow
Red
LD48-xx-xxxW
-DC Supply
No Wire
-LED LED Cathode Conn.
+LED LED Anode Conn.
+DC Supply
+V
IN
-V
IN
Pin
1
15
12
13
24
Color
Black
White
Blue
Yellow
Red
LD48-xx-xxxWA
-V
IN
-DC Supply
PWM, On/Off
V
ADJ
-LED LED Cathode Conn.
+LED LED Anode Conn.
+V
IN
+DC Supply
MicroPower Direct
We Power Your Success - For Less!
292 Page Street Ste D Stoughton, MA 02072
•
Notes:
•
All dimensions are typical in inches (mm)
•
Tolerance x.xx = ±0.02 (±0.50)
•
Pin 1 is marked by a “dot” or indentation on the top of the unit
FAX: (781) 344-8481
•
TEL: (781) 344-8226
•
E-Mail: sales@micropowerdirect.com
MPD [ MICROPOWER DIRECT, LLC ]
