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how to make led driver 12v 20w

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mohsen158

New Member
hi
i want to make led driver for 2 led
input voltage is 12 volts and power of them is 20w
so i think need 1.6 A
now i need to led driver to fix current in 1.6 A
so how to make that driver? what is that map?
thank you
 

sagor1

Active Member
Most voltage regulators can be configured as constant current sources, just check the datasheets...

See:
 
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chemelec

Well-Known Member
No, The LM350 is an Adjustable Regulator and can be used as a Constant Current Source.
It is Similar to the LM317, But with Higher Current Rating. (3 Amps)
And it will need a Heat Sink on it.
 
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sagor1

Active Member
Sorry, I meant "adjustable" as well (implied). I use the LM338 types myself, very seldom any fixed regulator except for the 5V ones for digital circuits....
The LM338 is rated for 5A.
 

mohsen158

New Member
Sorry, I meant "adjustable" as well (implied). I use the LM338 types myself, very seldom any fixed regulator except for the 5V ones for digital circuits....
The LM338 is rated for 5A.
Thanks but demand of my current is about 1.7A so 5 A is very too,
Do you work with lm350 for that application?
 

sagor1

Active Member
Thanks but demand of my current is about 1.7A so 5 A is very too,
Do you work with lm350 for that application?
The LM338 will handle "up to" 5A. It does not mean you have to draw that much current. Based on that Youtube video, you can make a 1.6A current source with either the LM350 or LM338 with a 0.78 ohm resistor, very close to 3/4 ohms. You will likely have to use a combination of resistors to get the value you want.
The resistor should be rated at least at 2W heat dissipation in total, as it will dissipate that much heat. A 3W minimum to a 10W resistor would be best.
And, as chemelec says, you will need a heatsink for whatever regulator you choose.
 

chemelec

Well-Known Member
Either the LM350 or the LM338 will work as a Current Limit.
 

mohsen158

New Member
The LM338 will handle "up to" 5A. It does not mean you have to draw that much current. Based on that Youtube video, you can make a 1.6A current source with either the LM350 or LM338 with a 0.78 ohm resistor, very close to 3/4 ohms. You will likely have to use a combination of resistors to get the value you want.
The resistor should be rated at least at 2W heat dissipation in total, as it will dissipate that much heat. A 3W minimum to a 10W resistor would be best.
And, as chemelec says, you will need a heatsink for whatever regulator you choose.
Thanks
 
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