Help for design simplest circuit for 6*1wat white LED in parallel(LED Driver)

[IanB]

I don't need to dimming the LEDs. I just want to drive those in parallel.

Don't try to drive LEDs in parallel. You will most likely shorten their life and cause them to fail. LEDs must be driven in series, or individually with current balancing. Never in parallel.

[mariush]

As several people already told you here, driving the leds in parallel is a bad idea.  Serial is the way to go, more efficiency.

If you're worried that one of the leds will break down and kill all the leds in the chain, then do a compromise and make 2 or 3  sets with 2-3 leds on each set.  If one led breaks down, you're going to have lower brightness because only 2 or 3 out of the six leds will stop working.
If you're so worried that one of the leds will break down and interrupt the whole chain of leds, why don't you just add some jumpers that will take out the led out of the circuit if it fails?

You have 24v, it will be a shame not to just chain the leds and have high efficiency. Just add some jumpers to take leds out of circuit if needed :



If you want something stupidly simple, you can use led drivers like these (i used them in the picture above) :

http://www.digikey.com/product-detail/en/NSI45090JDT4G/NSI45090JDT4GOSCT-ND/3462437

Each of these diode like drivers does up to 160mA (adjustable with a plain resistor) but they can be paralleled to give more current. Since you have 1w leds that means you need about 300 mA so you can simply put two of these in parallel and adjust the current to 150mA each with the resistor and you're done.

These led drivers are more expensive but at least they don't need inductors and capacitors and other components so you save money there. Just make sure to read the datasheet and pay attention to thermals (leave enough copper around them so they can stay cool (relatively) )

[Rufus]

If you're worried that one of the leds will break down and kill all the leds in the chain,

Murata make thermistor like anti-fuse devices intended to permanently short out LEDs failing open circuit. Littlefuse make semiconductor parts like two terminal voltage triggered thyristors which are also intended to short out LEDs failing open circuit.