looking for constant current led driver 2A

[bengaltiger]

Hi,

I am new in this forum. I am sure I will have good start here.

I am looking for constant current led driver circuit with 1A to 2.6A current.

output voltage should be 4.2 volt.

Thanks in advance.

BT

 

[MikeMl]

Are you looking for a chip or other ready made solution, or do you want to roll your own out of basic parts?

What is the 4.2V? Is it the supply voltage or is it the max forward voltage drop across the LED at the highest operating current?

What supply voltage do you want to start from?

 

[bengaltiger]

Thanks Mike,
I want to make my own driver.

output should be 3.6 to 4.3 V and current between 1A to 2A (or 2.6A).

firstly I want to make it on my own. If it takes long time then I can buy.
I need help from you for the circuit and some tuto/info.

Regards,
BT

 

[MikeMl]

Ok, look at this. Pot adjustable from 0 to 2.5A from a 5V supply.

 

[bengaltiger]

many thanks,

can you explian a bit this circuit. I mean how to choose the value of R3 for 2A, is it 81 ohm?

What is part no. for U1?

Today I came accross one national IC LM4301, is it better to use?

Regards,
BT

 

[MikeMl]

With the pot set to 81Ω, the LED current will be 2A. You said that you want to vary the LED current. If you do not want to vary the LED current, then replace the pot with a fixed resistor.

There are hundreds of OpAmps that could be used. As I said, look for a low-voltage CMOS one which includes ground (Vee) in it's common-mode input range (called rail-to-rail in the industry).

The 4301 will work just fine, but is needs a similar power FET, it needs a special inductor, and a special Schottky diode.

 

[bengaltiger]

my gratitude.

can you please mention a OpAmps (part no.) for example , I can buy.

Can I have a circuit diagram using LM4301.

Regards,
BT

 

[MikeMl]

DigiKey link

 

[reetwikbhadra]

Constant current LED driver

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I have a 230V supply....il reduce it to a certain voltage level (i.e buck converter) so that it can drive suppose 20 LEDs......with 3.8V maxm VF and current rating of 30mA...