Specifications typical @ +25°C, nominal input voltage & rated output current, unless otherwise noted. Specifications subject to change without notice.
Key Features:
Input
Parameter
•
Constant Current Output
Input Voltage Range
•
Wide 7V to 30V Input Range
Maximum Input Voltage
Input Filter
•
95% Efficiency
Output
•
Miniature MiniDIP Case
Parameter
•
500 mA to 700 mA Output
Output Voltage Range
Output Current
•
Meets EN 60950
Output Current Accuracy
Output Power
•
1.6 MHrs MTBF
Efficiency
•
Digital & Analog Dimming!
Capacitive Load
Operating Frequency
Ripple & Noise (20 MHz)
Temperature Coefficient
Thermal Impedance
Output Short Circuit
Environmental
Parameter
Operating Temperature Range
Storage Temperature Range
Cooling
Humidity
Lead Temperature (Solder)
Physical
Case Size
Case Material
Weight
Remote On/Off Control
Parameter
DC/DC On
DC/DC Off
Remote Pin Drive Current
Quiescent Input Current
(Shutdown Mode)
PWM Dimming
Parameter
Operation Frequency
Switch On Time
Switch Off Time
Output Current Adjust Range
Analog Dimming
Parameter
Input Voltage Range
Output Current Adjustment
Control Voltage Range Limits
Drive Current
EMC Compliance
EMI/RFI
Electrostatic Discharge (ESD)
RF Field Susceptibility
Electrical Fast Transients/Bursts On Mains
EMS Immunity
Reliability Specifications
Parameter
MTBF
Conditions
Min.
7.0
0.5 Sec
Internal Capacitor
Typ.
24
Max.
30.0
40.0
Units
VDC
VDC
Conditions
Min.
Typ.
2
V
IN
= 30V
See Model Selection Guide
See Model Selection Guide
See Model Selection Guide
See Model Selection Guide
70
See Model Selection Guide
Max.
28
Units
VDC
47
450
±0.05
µF
kHz
%/
º
C
º
C/W
Natural Convection
+40
Regulated At Rated Output Current
Conditions
Ambient
Case
Min.
-40
Typ.
+25
Max.
+71
+105
+125
95
260
Units
º
C
º
C
-40
Free Air Convection
RH, Non-condensing
1.5 mm From Case For 10 Sec
%
ºC
0.80 x 0.40 x 0.27 Inches (20.32 x 10.16 x 6.88 mm)
Non-Conductive Black Plastic (UL94-V0)
0.092 Oz (2.6g)
Conditions
Min.
Typ.
Max.
Units
Open or 0.3V < V
ADJ
<1.25V
V
ADJ
<0.15V
1
mA
25
µA
Typ.
Max.
1.0
Units
kHz
nS
nS
%
Units
VDC
%
VDC
mA
V
ADJ
= 1.25V
V
IN
= 30V
Conditions
Recommended Maximum
Min.
200
200
0
Conditions
At V
ADJ
Input (Pin 2)
On
Off
V
ADJ
= 1.25V
Radiated/Conducted
Class A
Class A
Class A
Min.
0.0
25
0.30
0.0
100
Typ.
Max.
1.25
100
1.25
0.15
1.0
MicroPower Direct
292 Page Street
Suite D
Stoughton, MA 02072
USA
T:
(781) 344-8226
F:
(781) 344-8481
E:
sales@micropowerdirect.com
W:
www.micropowerdirect.com
EN 55015 (CISPR22)
IEC/EN 61000-4-2, -6, -8
IEC/EN 61000-4-3
IEC/EN 61000-4-4
EN61547
Min.
1.6
Typ.
Max.
Units
MHours
Conditions
MIL HDBK 217F, 25
º
C, Gnd Benign
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Model Selection Guide
Input
Model
Number
LDM24-14-500
LDM24-17-600
LDM24-20-700
Voltage
(VDC)
Range
7.0 - 30.0
7.0 - 30.0
7.0 - 30.0
Voltage
(VDC)
Range
2.0 - 28.0
2.0 - 28.0
2.0 - 28.0
Max
(mA)
300
500
700
Output
Current
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Maximum
Power
(W)
Ripple &
Noise
(mV P-P, Max)
Efficiency
(%, Typ)
Package
Accuracy
(%)
±10
±10
±10
14
17
20
450
450
450
95
95
95
14 -Pin MiniDIP
14 -Pin MiniDIP
14 -Pin MiniDIP
Notes:
1. A reversed power source could damage the unit.
2. No connection should be made between input ground and the output.
3. These are step-down devices, the maximum output open voltage is
equal to the input voltage.
4. The V
ADJ
input should be left open if not used. Grounding V
ADJ
will shut the unit
down. Connecting V
ADJ
to V
IN
may damage the unit.
5. Exceeding the specified maximum output power could cause damage to the unit.
Typical Connection:
DC/DC Input
Connection Notes:
To comply with EN61000-4-5, a TVS should be installed before the input filter components. A 3.0SMCJ24A or SMCJ24A is recommended. The TVS max clamping voltage (@max peak pulse
current V
C
) must be 40V. This will prevent any surge from exceeding the maximum input of the driver (40 VDC). Exceeding the maximum input rating could damage the driver.
The filter shown (C
1
, C
2,
C
3
and L
1
) will help to meet conducted emission requirements. With the addition of the filter, the unit should meet the levels of EN 55015.
Typical Connection:
AC/DC Input
Connection Notes:
This is a distributed (or two-stage) AC connection. In this configuration, the AC line in (85 to 264 VAC) is connected to the
MPM-20S-24EPB,
a compact 20W AC/DC
power supply. The
MPM-20S-24EPB
provides a tightly regulated 24 VDC output at 833 mA. The 24 VDC output powers the LED driver.
The two stage approach can simplify the safety approval process (most AC/DC power supplies on the market are approved to EN 60950) and may increase design flex-
ibility. Besides the output voltage/current ratings, other specifications to consider when selecting the input AC/DC supply might include input range, case size, efficiency,
EMI ratings and operating temperature range.
Note: The output current adjustment circuit shown in both connection diagrams is discussed on page 4.
292 Page Street Ste D Stoughton, MA 02072
•
TEL: (781) 344-8226
•
FAX: (781) 344-8481
•
E-Mail: sales@micropowerdirect.com
PWM Output Current Control
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An LED operates at its maximum efficiency when
operated at the rated drive current specified by
the manufacturer. Operating an LED at lower than
its rated forward current not only decreases the
system efficiency; but may cause color (or wave-
length) shifting. In illumination applications, this
could cause visible changes to lighting.
A preferred method is using pulse width modula-
tion (PWM). As shown at left, the output current
is adjusted by applying a PWM signal to the V
ADJ
input. By varying the signal duty cycle the average
output current is adjusted up or down. To avoid
visible flicker, the PWM signal should be greater
than 200 Hz.
For duty cycles (DPWM) between 0.1 and 1, the
output current is derived by the formula:
PWM Control Signals
I
NOM
= I
MAX
X D
PWM
The V
ADJ
input may be driven via an open collec-
tor transistor (as shown). The diode and resistor
suppress high amplitude negative spikes that may
be caused by the drain-source capacitance of the
transistor. Negative spikes on the control input of
the unit could cause errors in output current or
erratic operation.
The V
ADJ
input can also be driven by the open drain
output of a microcontroller. Again, any high amplitude
negative spikes that may be caused by the drain-
source capacitance of the FET must be supressed.
PWM Dimming Application
A simple method of achieving digital (or PWM) dimming is by using a 555 timer again. The formulas for calculating the frequency and duty cycle are included
to apply a series of pulses to the V
ADJ
input, as illustrated above. Again, we are in the MPD application note “Driving
LEDs”.
powering the LED driver with the
MPM-20S-24EPB
AC power supply.
The diodes (D
1
and D
2
) allow duty cycles below 50% to be set. Diode D
1
The 555 operates over a supply voltage range of 4.5 VDC to 18VDC. Here it is bypasses R
2
while C
6
is charging. Diode D
2
is optional (but recommended),
connected to the 15 VDC output of the
SR7805
switching regulator (also driven essentially blocking R
2
during the charge period. Theoretically, this circuit will
by the
MPM-20S-24EPB).
Care should be taken to minimize ripple at the V
CC
allow for duty cycles over a range of approximately 5% to 95%. If manual
input. Excess ripple could cause timing errors.
adjustment is desired, a potentiometer may be substituted for R
2
(with some
adjustment of the circuit).
The timer is connected for astable (free run) operation. The frequency is set
by R
1
, R
2
and C
6
. The timing capacitor (C
6
) charges through R
1
and D
2
. When The size of C
6
is generally not critical, but it should be as low leakage as pos-
it reaches the level of
2/3
V
CC
, the discharge pin (pin 7) goes low and C
6
will sible. In order to avoid excessive current flow through the internal discharge
discharge through D
1
and R
2
to the internal discharge transistor. When the C
6
transistor, it is recommended that R
1
be at least 5 k .
voltage drops to
1/3
V
CC
, the discharge pin goes high and C
6
begins to charge
MicroPower Direct
•
292 Page Street Ste D Stoughton, MA 02072
•
TEL: (781) 344-8226
•
FAX: (781) 344-8481
•
E-Mail: sales@micropowerdirect.com
Analog Output Current Control
(V
CNT
= 5V)
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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.
The simple analog circuit at left uses a 15W
DC/DC converter operating off a 12 VDC
input line, to keep the input to the LED
driver at 24 VDC.
The POL regulator, 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 current level of the LED
driver. This level is equal to:
V
ADJ
=
R
2
X V
CTRL
R
1
+ R
2
Analog Output Current Control
(5 - 30 V
IN
)
In the second circuit, the input DC/DC has
been changed to a higher power model,
and the POL regulator 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.
When using the analog control input, the
nominal output current is equal to:
I
NOM
= I
MAX
x
V
ADJ
1.25
Mechanical Dimensions
The V
ADJ
input should be left open if not
used. Grounding V
ADJ
will shut the unit
down. Connecting V
ADJ
to directly to +V
IN
may damage the unit.
Pin Connections
Pin
1
2
7
8
14
-V
IN
V
ADJ
+LED
+V
IN
Function
-DC Supply
PWM, On/Off
LED Anode Connection
+DC Supply
-LED LED Cathode Connection
Get a full explanation of the
circuits in this datasheet and
more in “Driving
LEDs”.
Available free at the
MPD
website
MicroPower Direct
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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
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