I'm thinking I might use 14 7135s in parallel. I'm using 5xcree xml easy white leds, I could power it off of a 4s lifepo4 pack which would give around 12.8-12v for much of its life.
I've been thinking about controlling it with an attiny chip. I think I'll have a thermistor next to the leds to check the temperature and three modes. It will switch through them based on presses. The first mode will apply voltage to all 14 7135 chips vdd, the second mode will apply power to 7 amc 7135 chips vdd, the third mode will apply power to 3 of them.
I just had a novel idea. From my understanding pwm does not increase efficiency of the leds, it just decreases power draw. I could however connect a pot to a larger attiny chip and have 14 "steps", I would ivied the pot into 14 steps, the top having all 14 of the 7135 chips being powered, and the bottom only having 1. This would wallow the efficiency to increase as the power dropped. How does this sound?
smallest attiny with ADC is about 3mm x 3mm size. Remember that you have 14 7135s and 14 (or 28) FETs. Overall pot idea is good but WHY you don't go proper driver route instead of 7135s...I could however connect a pot to a larger attiny chip and have 14 "steps"
Not really - the MCU can drive 7135s directly, if they're connected conventionally on the low side of the LEDs and any turned on together can have their Vin pins connected together, driven by a single MCU output.And so you will need 14 FETs (or 28 if using N-P FET pair) to switch power to 14 7135s...
Ah - I'd been thinking or regular XM-Ls - my mistake.@caver I have 5 cree xml easywhite 12v leds. I would wire them in parallel. I'm hoping to run them at 1 amp each, for 5 amps total, all in parallel. I will most likely run then slightly below that incase the vf is different on them so if one is a current hog it doesn't go over spec. at 1 amp the vf is about 12.5 volts.