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Typical Application for Meanwell LDD DC-DC Constant Current LED Driver

Meanwell LDD series DC-DC Constant Current LED driver is designed to balance the current for a LED circuit and extend lifetime of the system. Here are some features of this range:

  • Wide input and output range
  • High efficiency up to 97%
  • Built-in PWM dimming and remote control function
  • Miniature size 22.6×9.9×8.9 mm
  • Various output options: 300mA, 350mA, 500mA, 600mA, 700mA, 1000mA
  • High reliability with 3 years warranty

Now let’s look at an example of a LED lighting system with LDD-300L implemented:

This application consists of:

  • LEDs, 1W 350mA each x 50
  • (AC-DC PSU) Mean Well LPV-100-36 x 1
  • (DC-DC PSU) Mean Well LDD-350L x 5
  • (DC-DC PSU) Mean Well SD-25C-12 x 1
  • PWM Controller / Dimmer x 1


  • Fan
  • Temperature Sensor

This example uses LPV-100-36 as the main driving power supply and uses LDD series to lit and dim LED Lighting Circuits with PWM dimmer. Let’s look at this in details:

1. In each string of the circuit, LEDs are wired up in series which consists of 10 x 1W @350mA LEDs. So the total wattage is about 10W, and total forward voltage is about 30Vdc.

2. The output voltage of LDD-350L is 2~32Vdc. 30V is within the range. According to the spec, LDD must have input voltage greater than output. Therefore we need a supply greater than 30V. Given that the total wattage required for LEDs is 50W and we have other electronics in the circuit, we have chosen the 100W Meanwell LPV-100-36 (36Vdc output).

3. Five strings of LED lights are wired in parallel, thus each LDD-350L have input of 36Vdc and output of around 30V@350mA.

4. On the input side of LDD-350L, there is a DIM pin which is connected to the PWM dimmer for lighting control.

5. On the top left corner of above diagram, we have also incorporated a DC to DC converter (SD-25C-12) to convert 36Vdc down to 12Vdc to power PWM dimmer, fan and temperature sensor etc…