Hi all,
I'm working on a micro controller project to do race timing for rowing regattas. It's coming along pretty nicely and I want to add one component: A finish light that will be turned on and off by the microcontroller.
The light needs to be seen from a distance in sunny conditions. I want to use an array of 9 Cree XP-E2's with appropriate reflectors (Ledil spot beam).
The main unit will have a 12V supply, and to keep the wire gauge down, I want to use that for the finish light as well.
The red Cree XP-E2 that I plan to use have a forward voltage of 2.2V and need 350 mA.
I'm thinking of using this LED driver: MPS MP3398L, does 4 string @ 350mA, takes 4.5 - 28V
That is as far as I got with Google, and zero experience building anything like this
My questions:
1) Should I add a voltage regulator that steps down my 12V to 5V or 6V so that I will three string of 3 LEDs that. I think they will run fine on a slightly lower voltage? Or use 12V to drive 5, and put the other 4 together with a resistor to get to the right voltage over the remaining LEDs
2) I would like to be able to dim the lights. The LED driver supports both PWM and analog dimming. I want the dimming to be adjustable on the light device itself (ie, not pass a PWM signal from the controller). So the analog dimmer sounds the easiest? Using a potentiometer in a voltage divider to get the desired 0.44V - 1.54V the driver expects.
And the real question, does the above make sense at all? Is it the "right" way to do this?
I'm hoping to design my own PCB later (never done that either, but it sounds like fun) to make it into a nice package.
Any and all info/pointers would be much appreciated!
Bas
I'm working on a micro controller project to do race timing for rowing regattas. It's coming along pretty nicely and I want to add one component: A finish light that will be turned on and off by the microcontroller.
The light needs to be seen from a distance in sunny conditions. I want to use an array of 9 Cree XP-E2's with appropriate reflectors (Ledil spot beam).
The main unit will have a 12V supply, and to keep the wire gauge down, I want to use that for the finish light as well.
The red Cree XP-E2 that I plan to use have a forward voltage of 2.2V and need 350 mA.
I'm thinking of using this LED driver: MPS MP3398L, does 4 string @ 350mA, takes 4.5 - 28V
That is as far as I got with Google, and zero experience building anything like this
My questions:
1) Should I add a voltage regulator that steps down my 12V to 5V or 6V so that I will three string of 3 LEDs that. I think they will run fine on a slightly lower voltage? Or use 12V to drive 5, and put the other 4 together with a resistor to get to the right voltage over the remaining LEDs
2) I would like to be able to dim the lights. The LED driver supports both PWM and analog dimming. I want the dimming to be adjustable on the light device itself (ie, not pass a PWM signal from the controller). So the analog dimmer sounds the easiest? Using a potentiometer in a voltage divider to get the desired 0.44V - 1.54V the driver expects.
And the real question, does the above make sense at all? Is it the "right" way to do this?
I'm hoping to design my own PCB later (never done that either, but it sounds like fun) to make it into a nice package.
Any and all info/pointers would be much appreciated!
Bas