Hi, I'm andrea.
I study electronic engineering and I'm trying to design horticulture led lamp. I'm sorry but I don't speak English very well.
I have designed some constant current circuits but now I want to design something different with modular approch.
can I post links to products?
I have chosen the LEDs (2 LEDs): 37 Volt, 720 mA --> 24.5 W
I have chosen the LED heat sink.
My project consists of a 60-100 watt power source, 4 leds in parallel. I need to convert 220v AC power line to 37 V DC. I didn't choose the 220V ac-dc main power supply so I don't know its output voltage (it could be 40 Volts). I want to design the most efficient constant current circuit for drive every single led.
I've chosen to power the LEDs in parallel and not in series because I want to use a modular approach (if I want to use 10 LEDs I just have to change the power supply).
I want to design an efficient circuit with minimal heat problem. could you help me find the most suitable components to drive the leds? I know how to design constant current circuit but I don't know which one is the best.
can I post links to products and sites?
Thank you
Andrea

 

Hello,

You do not need a 37 Volts power source, but a 700 mA constant current source.
Leds are current driven and not voltage.

Bertus

 

Thanks for answer. I know this. I just wanted to point out that I haven't chosen the 220v main transformer

 

This might work with no need for AC to DC supply.
30 watt 220VAC to dc

 

Hello,

@ronsimpson , the version you show is 900 mA, the TS needs about 700 mA.

He could have a look at some 700 mA meanwell drivers:
https://nl.mouser.com/MEAN-WELL/Power/Power-Supplies/LED-Power-Supplies/_/N-axgjt?P=1yxt6tzZ1z0zl9b

Bertus

 

This is another problem. I have found many boards and products that perform the function I am looking for. these products are similar to the ones you linked to me but I don't want to buy from chinese sites. the other problem is that i cant spend much money.

I can write here the specifications that I have decided for my project:
- quite cheap;
- I want to use only one main power line;
-I don't want to use components from chinese sites like aliexpress. I always use Chinese boards and components because they perform functions well and are cheap. this time I want to use safer and more reliable electronic components.

I would like to buy everything from sites that I believe are reliable such as mouser or digikey, and I want to sell products quickly.
thanks

 

( I want to use only one main power line from 220v and then I want to drive every led with constant current (720 mA),

 

Hello,

Did you have a look at what I posted:
He could have a look at some 700 mA meanwell drivers:
https://nl.mouser.com/MEAN-WELL/Power/Power-Supplies/LED-Power-Supplies/_/N-axgjt?P=1yxt6tzZ1z0zl9b

Bertus

 

You can't parallel LEDs unless you parallel a set of (LED+Resistor). Your most efficient method would be PWM and not really constant current, but constant average current.

To get your raw voltage you will need to design a line switchmode power supply with isolation.

 

You can't parallel LEDs unless you parallel a set of (LED+Resistor). Your most efficient method would be PWM and not really constant current, but constant average current.

To get your raw voltage you will need to design a line switchmode power supply with isolation.

Are you sure? the solution proposed by bertus seems good to me.
https://www.mouser.com/ProductDetail/MEAN-WELL/LDD-700H?qs=erfQA2AIGbXYF3x8KGE0pA==
I can connect one LDD-700H in series to every LED end connect the four pairs in parallel.

 

Hello,

Did you have a look at what I posted:
He could have a look at some 700 mA meanwell drivers:
https://nl.mouser.com/MEAN-WELL/Power/Power-Supplies/LED-Power-Supplies/_/N-axgjt?P=1yxt6tzZ1z0zl9b

Bertus

this solution seems good to me. I found https://www.mouser.com/ProductDetail/MEAN-WELL/LDD-700H?qs=erfQA2AIGbXYF3x8KGE0pA==
I would like to power with 720 mA and not 700 mA but I don't find anything cheap.
I want to design a component like this to save money. the problem is efficiency and heat.
Do you have any idea what could be the best custom alternative?
Do you have a tip on how to economically convert 220VAC to 9-56Vin of LDD-700H component?
Thanks for all

 

Hello,

You couls have a look at this driver:
https://nl.mouser.com/MEAN-WELL/Pow...yzvvqx?P=1z0zl9bZ1yxt6tzZ1y8oey6&Ns=Pricing|0

It can drive 2 or 3 of your leds in series.

Bertus

 

Hello,

You couls have a look at this driver:
https://nl.mouser.com/MEAN-WELL/Power/Power-Supplies/LED-Power-Supplies/XLG-100-Series/_/N-axgjtZ1yzvvqx?P=1z0zl9bZ1yxt6tzZ1y8oey6&Ns=Pricing|0

It can drive 2 or 3 of your leds in series.

Bertus

I need to design a led block with this https://www.mouser.com/ProductDetail/MEAN-WELL/LDD-700H?qs=erfQA2AIGbXYF3x8KGE0pA== in series to the LED. I want these blocks in parallel. I don't want use one component to drive 2 or 3 leds.
can you answer to this part of my message?
"
I would like to power with 720 mA and not 700 mA but I don't find anything cheap.
I want to design a component like this to save money. the problem is efficiency and heat. Do you have any idea what could be the best custom alternative?
Do you have a tip on how to economically convert 220VAC to 9-56Vin of LDD-700H component?
"
Thanks
Andrea

 

Hello,

When you want to drive single leds, have a look at this 700 mA driver:
https://nl.mouser.com/ProductDetail/MEAN-WELL/APC-35-700?qs=21bV/TPs%2Bw9S34m0jXtW0A==

You will not notice the difference between 700 and 720 mA.
You will need one for each led in this case.

Bertus

 

Hello,

When you want to drive single leds, have a look at this 700 mA driver:
https://nl.mouser.com/ProductDetail/MEAN-WELL/APC-35-700?qs=21bV/TPs%2Bw9S34m0jXtW0A==

You will not notice the difference between 700 and 720 mA.

Bertus

maybe I haven't explained my problem well.
I have attached the idea of the project. the constant_current_circuit+LEDs blocks are connect in parallel
is it okay to use LDD-700H series component with a 37v 720ma led?
Do you have any idea what could be the best custom alternative circuit to LDD- 700H? my priorities are efficiency and heat.
thanks for all
Andrea

 

Hello,

Using the LDD 700, you will need a power supply of at least 40 Volts as your leds require 37 Volts and the voltage drop of the LDD 700 is minimum 3 Volts.
An 48 Volts power supply would work fine.
I would take a 4 ampere power supply, to have a little headroom, for 4 leddriver / led combinations.

Bertus

 

thanks for answer.
I prefer design the constant current circuit. I want use LM317HVT/NOPB.
what is the best constant current circuit? there are a lot of circuit but I don't know what is the best option.
specs: vin=40v, corrent_max= 2.5A.
I want set 720 mA with the most efficient circuit. I will buy heat sink for led and lm317

 

Hello,

The LM317 will likely not work as you need a larger voltage drop of about 4 volts (3 volt for the regulator and 1.25 volt for the resistor)
The LDD 700 will be more effeicient.

Bertus