# 1 watt 350 ma power led driver circuit design?



## mir_as82 (Aug 25, 2009)

hi i have already joined this forum site. i search driver for 1 watt 350ma white power led. is there any sample circuit for this? does anyone have circuit shematic diagram? some professional electronic firms produce like this products.i tried to find their pcb design and circuit diagrams but i could not find any. does anyone have like this project? so could you post?


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## yellow (Aug 25, 2009)

1st idea: You end up much smaller (and more reliable) and cheaper by purchasing a driver.

but: f.e.
www.national.com, 
klick "power management" on left
type in Your data on the right
klick "start design"
receive a few hits
check the hits for the parts recommended (f.e. number of contacts. More contacts - more difficult to solder. Or efficiency, or ...)
then check the datasheet which usually features a few design possibilities
... and build the one liked best


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## Illum (Aug 25, 2009)

350ma drivers are common, but searching for an ideal one is a pain if you don't know what your input power supply is, AC? DC? is it greater than the Vf of the LED [step down needed]? is it lower [step-up/boost needed]?

A value of power input would help


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## Gunner12 (Aug 25, 2009)

Knowing what input you will have for the driver would be quite helpful.

Also, it is much easier to just buy a driver instead of designing one.

:welcome:


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## Illum (Aug 25, 2009)

Gunner12 said:


> Knowing what input you will have for the driver would be quite helpful.
> 
> Also, it is much easier to just buy a driver instead of designing one.
> 
> :welcome:



sometimes building one is half the fun, and especially useful if there is very limited space where you have to cram component parts into an irregular shape for parts to fit correctly


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## mir_as82 (Aug 26, 2009)

Illum said:


> 350ma drivers are common, but searching for an ideal one is a pain if you don't know what your input power supply is, AC? DC? is it greater than the Vf of the LED [step down needed]? is it lower [step-up/boost needed]?
> 
> A value of power input would help


 
my input voltage is AC 220V ac. i tried to find inside design of professional firms but i could not find any pcb or any circuit shematic diagram.


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## Steve K (Aug 26, 2009)

have you looked at the TinySwitch products? They are designed to work with AC mains power.

http://www.powerint.com/en/products/tinyswitch-family/tinyswitch-iii

regards,
Steve K.


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## Illum (Aug 26, 2009)

mir_as82 said:


> my input voltage is AC 220V ac. i tried to find inside design of professional firms but i could not find any pcb or any circuit shematic diagram.




Offline LED drivers often don't have schematics on line, I'm not sure why...perhaps its a trade secret. 
Since your design implementation concerns AC-DC conversions, I would recommend just buying a prebuilt LED driver.

There are the dedicated drivers [110V, 125V, 220V, Xitanium], and there are switch modes [100-240V, Magtech, lightech]

How many LEDs are you planning to use with your system? the smallest unit I know is the Magtech WH-L03U-350:
Input: 100-240VAC 120ma 50/60Hz 
Output: 12VDC Max 350ma

at $14 its significantly cheaper than most offline LED drivers, CREEs are about 3.3V in at 350ma so its capable of driving up to 3 LEDs.


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## Capo_au (Aug 26, 2009)

The AX2002 Led driver can work off AC and DC up to 23V so it may be of some interest to you.

Its data sheet has some basic circuit diagrams.


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## mir_as82 (Aug 28, 2009)

input:220V ac.
output current=350ma
output voltage=3V

and i dont want to buy any driver.i want to make it by myself. i really could not any totally prepared power led driver circuits(pcb or circuit diagram).i mean drives which have made by some firms.


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## Mr Happy (Aug 28, 2009)

It is very dangerous to work with AC mains inputs for low voltage power supplies.

The safest way to do it is to use a transformer with a bridge rectifier and filter capacitor to produce a smoothed and rectified low voltage supply of about 6 V DC. Then use a part like the LM317 in a current regulating configuration to produce a 350 mA constant current supply for the LED.

Be very careful with the mains side of the transformer. Use secure insulated connections and include a 1 A fuse in case of accidental short circuits.


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