How to #2 - Use LTC3780

This is a Buck Boost converter, which is a kind of high efficient power supply module with Constant voltage, constant current, under-voltage protection.

What is Buck Converter ?

It can step down the voltage

What is boost converter ?

It can step up the voltage

And This LTC3780 is Buck boost converter !

If you want to watch the video Click Here

And do check out my channel Click Here

Step 1: What Are These Pots ?

Far right one is for Under voltage protection (VV) and it is mostly used for Solar Charging

What does it mean ?

The device can monitor a DC-DC output voltage and quickly disconnect the power source from the DC-DC input load when an overvoltage condition occurs. A power-OK output signals when the DC-DC input voltage falls below an adjustable threshold.

Center one is for Constant Current ( CC)

What does it mean ?

A constant current is that does not change its intensity with time.

Left one is for Constant Voltage ( CV )

What does it mean ?

Same as CC does not change over time

Step 2: How Much Power Can It Handle ? and Efficiency ?

It depends on the board the one which I have used can handle Up to 130W

But after 80W it needs to increase the Heat Dissipation

And

The sweet spot for the efficiency is 98% at 12V

Step 3: Lets Power It Up !

I had a bunch of LED's soldered in parallel

After powering it up I have to say it worked like charm and I was able to control the voltage and current to change the intensity of the LED's

Step 4: Ending Notes

From where I got mine ?

Gearbest - Click Here

LTC3780 - Click Here

Volt Amp Display - Click Here

Shipping Time ?

It took 2 weeks for me to reach India

Packaging ?

Excellent Static proof bags with bubble wrap in it

Note - In the Next Instructables And video I am going the built a power Supply out of it !

So For updates you can check my Youtube Channel, Facebook And Instagram

Hope you like this Instructables

Happy Making !

Comments

[Pokornz]

Thank you for the instructable! However, I would like to ask you to remove the part about efficiency since it is a misleading statement. If you take a closer look at the "Efficiency and Power Loss" figure, it says in the subtitle "Vout = 12V". It is true that the plotted curve implies that the greatest efficiency will be achieved when the Vin = 12V, but considering the fact that the input voltage is the same as the output voltage, the circuit is essentially not providing any conversion. That is the reason for the 98% efficiency - the unit is only passing through the same voltage level.

To conclude, your statement "The sweet spot for the efficiency is 98% at 12V" is true only if the output voltage and input voltage are both 12V, which then defeats the purpose of using the LTC3780 unit.

Feel free to reply and let me know your thoughts.

[Ofgrid]

Sorry, no, these specs actually are very useful. Take a 12 V system like automotive, marine, photovoltaic. There you have a system voltage somewhere around 12 V. Yet when you don't need "somewhere" but more or less "exact" 12 V, that is a regulated power supply, the LTC3780 is a perfect match.

Furthermore, if your input and output voltages are significantly different, either a simple buck or boost converter will do the job. Thus the LTC3780 has its highest efficiency in the case where it's most useful

[Pokornz]

My point is that if the input is X volts and the output is also X volts, the efficiency will most likely also be around 98%, even if X =/= 12V. In other words, the unit is not 98% efficient at 12V, but it is 98% efficient if the output voltage is equal to the input voltage.

I'm not saying the LTC3780 is not useful for the situations you describe. I'm just saying the statement "The sweet spot for the efficiency is 98% at 12V" is wrong, because you would achieve similar efficiency at different voltages as well.

[Duret-RobertL]

Hello ! I tried to used one of those for a variable psu however when I tried powering up the board, it wouldn't output anything and the FAULT led was lit.. I powered it up with a 12V playstation3 power supply and tries measuring the output voltage using a voltmeter. Did I do something wrong or was it just a doa board ? Could anyone help me please :)

[ErwinB19]

Same here - using PC power supply.
Did you ever get feedback, solution?
Too much C is my guess.....

[Nematic!]

try turning the 3rd pot

[danielglenn1234]

That didn't work for me as I am having the same problem but turning the 3rd pot did nothing

[Duret-RobertL]

I eventually figured out the solution which was indeed turning the 3rd pot. However it is a multiturn pot with no locking so you have to try turning it many times in each directions. The FAULT led also turns on if your outputs are directly connected or if the input voltage is too high

[danielglenn1234]

I didn't realise how many times you could turn the pot! I kept turning until the fault led turned off. I wish it would have been mentioned in the video that this was necessary instead of saying we didn't need to touch it but I got it working. Thanks so much for your help!

[JamieC142]

can i change the current pot whit a 220k ohm pot impart from the 200k pot?

[Nematic!]

Yes it won't make any difference because it is making voltage difference if doesn't works let me know

[PedroR207]

hi, i use a 220k potenciometer on the amp and dont work i try a 100k and nothing, the position of lines to potenciometer are correct and potenciometer are good what do you say.

[throbscottle]

Nice useful instructable

[Omar_Kassem90]

Can i power it up using 24v 5A and if i do wil the output voltage and current be higher?

[JohnathanW15]

what resistor value on the CC terminals would set it wide open (no current limit) Im trying to save space and the pots are slightly higher than the caps so Im taking them off for a thinner case. I need 24-26v (currently resistors replacing CV are giving 26) and no limit on amperage. The device attached draws 2amps max but im not quite sure how to tell if its limited by the 3780/psu or not as i cant force device to max power and dont have power resistors I wouldnt turn red hot

[kamhagh]

I have one which outputs stuff correctly. but the OP amp gets TOASTY! I used a tiny heatsink on the op amp (lm358).

can anyone tell me if their's do that too? because litteraly the second Ibought it I accidentally smashed the circuit with my screw driver while adjusting those annoying pots :D

sadly the second one I bought had the same thing happen to it. only this time it made a giant spark on constant and now it gives me a constant 2.3v and the ltc3780 heats up very quickly

[AaravM]

Hi can i power it using a 12 volt2 amp adapter (the tata sky ones)

[Nematic!]

Yes but you won't be able to exceed 24W power I would recommended getting one 12v 5A or 10A smps

[pmondal2]

Sir can i power it with a atx power supply and can i power it more than 10amp power supply please help me.