LDM24-XX-XXX [MPD]
Miniature, Wide Input Constant Current DC/DC LED Drivers;
| 型号： | LDM24-XX-XXX |
| 厂家： | 
MICROPOWER DIRECT, LLC |
| 描述： | Miniature, Wide Input Constant Current DC/DC LED Drivers |
| 文件： | 总4页 (文件大小：607K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LDM24-xx-xxx
Miniature, Wide Input
Constant Current
DC/DC LED Drivers
Electrical Specifications
Specifications typical @ +25°C, nominal input voltage & rated output current, unless otherwise noted. Specifications subject to change without notice.
Key Features:
Input
Parameter
Input Voltage Range
Maximum Input Voltage
Input Filter
Conditions
Min.
7.0
Typ.
24
Max.
30.0
40.0
Units
VDC
VDC
• Constant Current Output
• Wide 7V to 30V Input Range
• 95% Efficiency
0.5 Sec
Internal Capacitor
Output
• Miniature MiniDIP Case
• 500 mA to 700 mA Output
• Meets EN 60950
Parameter
Output Voltage Range
Output Current
Output Current Accuracy
Output Power
Efficiency
Capacitive Load
Operating Frequency
Ripple & Noise (20 MHz)
Temperature Coefficient
Thermal Impedance
Output Short Circuit
Environmental
Conditions
Min.
2
Typ.
Max.
28
Units
VDC
VIN = 30V
See Model Selection Guide
See Model Selection Guide
See Model Selection Guide
See Model Selection Guide
• 1.6 MHrs MTBF
• Digital & Analog Dimming!
47
450
µF
kHz
70
See Model Selection Guide
0.05
%/ºC
ºC/W
Natural Convection
Regulated At Rated Output Current
+40
Parameter
Conditions
Min.
-40
Typ.
+25
Max.
+71
+105
+125
Units
ºC
Ambient
Case
Operating Temperature Range
Storage Temperature Range
Cooling
Humidity
Lead Temperature (Solder)
Physical
-40
ºC
Free Air Convection
RH, Non-condensing
1.5 mm From Case For 10 Sec
95
260
%
ºC
Case Size
Case Material
Weight
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)
Remote On/Off Control
Parameter
Conditions
Min.
Typ.
Max.
Units
DC/DC On
DC/DC Off
Open or 0.3V < VADJ <1.25V
VADJ <0.15V
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
VADJ = 1.25V
VIN = 30V
1
25
mA
µA
Conditions
Recommended Maximum
Min.
Typ.
Typ.
Max.
1.0
Units
kHz
nS
nS
%
200
200
0
100
MicroPower Direct
292 Page Street
Suite D
Conditions
Min.
0.0
25
Max.
1.25
100
Units
VDC
%
Input Voltage Range
Output Current Adjustment
At VADJ Input (Pin 2)
Stoughton, MA 02072
USA
On 0.30
1.25
0.15
1.0
Control Voltage Range Limits
VDC
mA
Off
0.0
Drive Current
EMC Compliance
EMI/RFI
Electrostatic Discharge (ESD)
RF Field Susceptibility
Electrical Fast Transients/Bursts On Mains
EMS Immunity
VADJ = 1.25V
T: (781) 344-8226
F: (781) 344-8481
E: sales@micropowerdirect.com
W: www.micropowerdirect.com
Radiated/Conducted
Class A
EN 55015 (CISPR22)
IEC/EN 61000-4-2, -6, -8
IEC/EN 61000-4-3
IEC/EN 61000-4-4
EN61547
Class A
Class A
Reliability Specifications
Parameter
MTBF
Conditions
MIL HDBK 217F, 25ºC, Gnd Benign
Min.
1.6
Typ.
Max.
Units
MHours
www.micropowerdirect.com
Model Selection Guide
www.micropowerdirect.com
Input
Output
Maximum
Power
(W)
Ripple &
Model
Number
Efficiency
(%, Typ)
Package
Voltage (VDC) Voltage (VDC)
Current
Accuracy (%)
Noise
(mV P-P, Max)
Range
Range
Max (mA)
300
LDM24-14-500
LDM24-17-600
LDM24-20-700
7.0 - 30.0
7.0 - 30.0
7.0 - 30.0
2.0 - 28.0
2.0 - 28.0
2.0 - 28.0
10
10
10
14
17
20
450
450
450
95
95
95
14 -Pin MiniDIP
14 -Pin MiniDIP
14 -Pin MiniDIP
500
700
Notes:
1. A reversed power source could damage the unit.
4. The VADJ input should be left open if not used. Grounding VADJ will shut the unit
down. Connecting VADJ to VIN may damage the unit.
5. Exceeding the specified maximum output power could cause damage to 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.
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 VC) must be Ϲ40V. 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 (C1, C2, C3 and L1) 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
www.micropowerdirect.com
PWM Output Current Control
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 VADJ
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
INOM IMAX X DPWM
=
The VADJ 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 VADJ 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 VADJ input, as illustrated above. Again, we are
powering the LED driver with the MPM-20S-24EPB AC power supply.
in the MPD application note “Driving LEDs”.
The diodes (D1 and D2) allow duty cycles below 50% to be set. Diode D1
bypasses R2 while C6 is charging. Diode D2 is optional (but recommended),
essentially blocking R2 during the charge period. Theoretically, this circuit will
allow for duty cycles over a range of approximately 5% to 95%. If manual
adjustment is desired, a potentiometer may be substituted for R2 (with some
adjustment of the circuit).
The 555 operates over a supply voltage range of 4.5 VDC to 18VDC. Here it is
connected to the 15 VDC output of the SR7805 switching regulator (also driven
by the MPM-20S-24EPB). Care should be taken to minimize ripple at the VCC
input. Excess ripple could cause timing errors.
The timer is connected for astable (free run) operation. The frequency is set
by R1, R2 and C6. The timing capacitor (C6) charges through R1 and D2. When
it reaches the level of 2/3 VCC, the discharge pin (pin 7) goes low and C6 will
discharge through D1 and R2 to the internal discharge transistor. When the C6
voltage drops to 1/3 VCC, the discharge pin goes high and C6 begins to charge
The size of C6 is generally not critical, but it should be as low leakage as pos-
sible. In order to avoid excessive current flow through the internal discharge
transistor, it is recommended that R1 be at least 5 k⍀.
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 (VCNT = 5V)
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The output current of the unit can also
be set by adjusting the voltage level on
the VADJ input to a value between 0.3V to
1.25V (IOUT 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 VADJ input) at 5 VDC. The resister
network of R1 and R2 can now be used
to set the output current level of the LED
driver. This level is equal to:
R2
+
V
ADJ
X V
CTRL
=
R1 R2
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 (D1) circuit connected in
parallel with the resistor network. The
regulator will maintain the voltage across
R2 and R3 at 2.5 VDC, insuring that the
1.25 VDC limit on the VADJ pin will not be
exceeded.
Analog Output Current Control (5 - 30 VIN)
When using the analog control input, the
nominal output current is equal to:
V
1.25
ADJ
I
NOM =IMAX
x
The VADJ input should be left open if not
used. Grounding VADJ will shut the unit
down. Connecting VADJ to directly to +VIN
may damage the unit.
Mechanical Dimensions
Pin Connections
Pin
1
Function
-VIN
-DC Supply
2
VADJ
PWM, On/Off
7
-LED LED Cathode Connection
+LED LED Anode Connection
8
14
+VIN
+DC Supply
Get a full explanation of the
circuits in this datasheet and
more in “Driving LEDs”.
Available free at the MPD website
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
MicroPower Direct
We Power Your Success - For Less!
292 Page Street Ste D Stoughton, MA 02072
•
TEL: (781) 344-8226
•
FAX: (781) 344-8481
•
E-Mail: sales@micropowerdirect.com
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