DC DC Converter

aaronik19 · Joined: 25 Apr 2011 Posts: 297

Dear All,

I have a project where I want to use DC DC Converter with constant current output of 350mA. I came across to LDD-350 from Meanwell. On the datasheet it states that the input should be between 9VDC to 36VDC while the output voltage is 2VDC to 32VDC at constant current of 350mA. Now on my board I have only 12VDC available.

Now the light fitting I am going to drive has 11 leds with 1 W each. So mathematically the voltage drop on each LED (all led are connected in series) is 2.85V which will end up to 31.4VDC.

My question is that whatever the voltage is in the input (ranging from 2V to 36V) the module will be capable to step up the voltage up to 36VDC?

Thanks for your help

Ttelmah · Joined: 11 Mar 2010 Posts: 19587

and this has to do with CCS C how?.....

General electronic question. Should be on a general electronic forum...

Remember it is going to draw just on 1A at 12v, and you have to provide the input and output filter.

temtronic · Posted: Sun Sep 27, 2015 5:23 am

At a glance the module could be used as the LED driver from a PIC,since it has PWM input and LEDs are a current device....

however

According to the spec sheet, in the Notes, #4, the output voltage will be 3 volts LOWER than the input voltage, so NO, it will not work as you thought.

This is a step down converter. It takes the input power and produces a FIXED constant current depending on the module (350ma in this case). Be sure your LEDs are rated for 350 ma !! At a 12 volts input, you get 9 volt output, so maybe 3 LEDs in series should light properly, you'll have to experiment.

Now you might, and I stress might, get working results if you group the LEDs in 4 columns of 3 though that's 12 LEDs and you have 11. I did this 25 years ago having a PIC control an opamp that powered 6 optotriac drivers and it's still working fine....

Sounds like what you 'want' is a stepup constant current converter that will take 12V DC, stepup to 36 Volts then feed a constant current module to power the LEDs.

Query. What LEDs are you using? 350ma seems a lot and must be a BRIGHT source of light ! Do you need dimming? Can you use a PIC with more I/O pins? Perhaps a high side Vreg in CC mode will work?

Jay