power driver for luxeon LED

Hi !
Il want to drive a 5W Luxeon powerled (7V and 700mA) with an efficiency better than 85 % (A PWM is needed, I dont want a simple resistor in serie with the bat.)
Is there a dedicated circuit for that ?

you can get buck, or boost converters from the Shoppe.
Shoppe

7V ? What batts are you using? Thats an off V.
For example, if you use 2x123 batts, you use a BadBoy, if you use a Voltage over that, you use a DownBoy.

OR, you can use one of Georges Fatman converters.
I think it will do 7V to a 5W led. And you can make it dimmable, with a Pot.
Taskled Website

I support George's http://www.TaskLED.com

I assume that since you referred to improving over using a resistor, that your Vin is > the LED Vf. Two sources I have successfully used:
- Georges80
- LEDdynamics / LED supply - buckpuck 3021 (I think that is the model)

Both have a wide input range, as long was you are above the LED Vf. Both are in the 85 - 90 % efficiency range, so comparable results.

Both work well, each has its own form factor advantages depending on your needs. The part from georges80 has a lower list price and looks more like a small PCB board. - very flat package.

The LED Dynamics part is packaged more like an oversize IC package. - smaller X / Y, larger Z dimension.

thank you for your assistance