MK180 on 5V

I would like to power two high power CREE LED from your board. They shall be supplied with 3,3V and 3A each. To limit the current at 12V output I need a very large resistor (capable to dissipate 26W) which gets very hot and is very heavy due to cooling.

Since the whole thing is for a model plane weight has to be limited.

Question: can I power the board with 5V bypassing the step-down like that:

When I have only 5V output I would only dissipate 5W with a much lighter resistor.
I also should bypass the diode D1 to avoid the voltage to drop I guess from another thread…

You can power it from 5VDC, however, keep in mind that the unit is no longer protected against polarity reversal and don’t forget to put a resistor in series with the leds.

Incredible response time!! Thank you!

So, I do not have to bypass the step down just power the whole thing with 5VDC and calculate the resistors for 5VDC?
I come to result of 0,57 and 5W to be dissipated:


No, you need to bypass the regulator otherwise it will not work.

Thanks again! This support is a good argument to buy Velleman products :wink:

I will try it that way…

Hello Guys. Yesterday i bought the mk180 Module. This Module ist ready for 9-12v DC. But i only have an 5V Output from another Module. Couldt anybody tell me how i can modifi the mk180 to get it working with 5V?

Yes, just read the above replies and look at the pictures. This question is already answered in this topic.

Yes i know, i think the 1st pic is the correct, but i dont know if i musst remove D1 and VR1

Yes, the regulator needs to be removed and bridged for 5VDC operation.